Thanks,
Dave...
A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
Norm
:Hello All,
: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:
:
:Thanks,
:
:Dave...
Thanks very much,
Dave...
:Hi Dave
:
: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:
: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:
:Norm
:
::Hello All,
:: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::
::
::Thanks,
::
::Dave...
I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
See if you can find any transformer with two secondary windings.
Norm
:Hi Norm,
: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:
:Thanks very much,
:
:Dave...
::Hi Dave
::
:: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::
:: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::
::Norm
::
:::Hello All,
::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::
:::
:::Thanks,
:::
:::Dave...
:Hi Dave
:
: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:
: See if you can find any transformer with two secondary windings.
:
:Norm
:
::Hi Norm,
:: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::
::Thanks very much,
::
::Dave...
:::Hi Dave
:::
::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::
::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::
:::Norm
:::
::::Hello All,
:::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::
::::
::::Thanks,
::::
::::Dave...
Thanks,
Dave...
:Hi Dave
:
: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:
: See if you can find any transformer with two secondary windings.
:
:Norm
:
::Hi Norm,
:: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::
::Thanks very much,
::
::Dave...
:::Hi Dave
:::
::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::
::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::
:::Norm
:::
::::Hello All,
:::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::
::::
::::Thanks,
::::
::::Dave...
Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
Norm
:Norm,
: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:
:Thanks,
:
:Dave...
::Hi Dave
::
:: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::
:: See if you can find any transformer with two secondary windings.
::
::Norm
::
:::Hi Norm,
::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::
:::Thanks very much,
:::
:::Dave...
::::Hi Dave
::::
:::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::
:::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::
::::Norm
::::
:::::Hello All,
::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::
:::::
:::::Thanks,
:::::
:::::Dave...
:Dave
:
: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:
:Norm
:
::Norm,
:: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::
::Thanks,
::
::Dave...
:::Hi Dave
:::
::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::
::: See if you can find any transformer with two secondary windings.
:::
:::Norm
:::
::::Hi Norm,
:::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::
::::Thanks very much,
::::
::::Dave...
:::::Hi Dave
:::::
::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::
::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::
:::::Norm
:::::
::::::Hello All,
:::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::
::::::
::::::Thanks,
::::::
::::::Dave...
Thanks,
Dave...
:I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
: Maybe there is a speacial way to connect the ends of the secondaries.
:
:Thanks,
:
:
::Dave
::
:: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
::
::Norm
::
:::Norm,
::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:::
:::Thanks,
:::
:::Dave...
::::Hi Dave
::::
:::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::::
:::: See if you can find any transformer with two secondary windings.
::::
::::Norm
::::
:::::Hi Norm,
::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::::
:::::Thanks very much,
:::::
:::::Dave...
::::::Hi Dave
::::::
:::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::::
:::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::::
::::::Norm
::::::
:::::::Hello All,
::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::::
:::::::
:::::::Thanks,
:::::::
:::::::Dave...
Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
Norm
:Norm,
: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:
:Thanks,
:
:Dave...
::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:: Maybe there is a speacial way to connect the ends of the secondaries.
::
::Thanks,
::
::
:::Dave
:::
::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::
:::Norm
:::
::::Norm,
:::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::
::::Thanks,
::::
::::Dave...
:::::Hi Dave
:::::
::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::
::::: See if you can find any transformer with two secondary windings.
:::::
:::::Norm
:::::
::::::Hi Norm,
:::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::
::::::Thanks very much,
::::::
::::::Dave...
:::::::Hi Dave
:::::::
::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::
::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::
:::::::Norm
:::::::
::::::::Hello All,
:::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::
::::::::
::::::::Thanks,
::::::::
::::::::Dave...
Thanks,
:Dave
:
: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
:
:Norm
:
::Norm,
:: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
::
::Thanks,
::
::Dave...
:::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
::: Maybe there is a speacial way to connect the ends of the secondaries.
:::
:::Thanks,
:::
:::
::::Dave
::::
:::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
::::
::::Norm
::::
:::::Norm,
::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:::::
:::::Thanks,
:::::
:::::Dave...
::::::Hi Dave
::::::
:::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::::::
:::::: See if you can find any transformer with two secondary windings.
::::::
::::::Norm
::::::
:::::::Hi Norm,
::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::::::
:::::::Thanks very much,
:::::::
:::::::Dave...
::::::::Hi Dave
::::::::
:::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::::::
:::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::::::
::::::::Norm
::::::::
:::::::::Hello All,
::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::::::
:::::::::
:::::::::Thanks,
:::::::::
:::::::::Dave...
Thanks,
:Dave
:
: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
:
:Norm
:
::Norm,
:: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
::
::Thanks,
::
::Dave...
:::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
::: Maybe there is a speacial way to connect the ends of the secondaries.
:::
:::Thanks,
:::
:::
::::Dave
::::
:::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
::::
::::Norm
::::
:::::Norm,
::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:::::
:::::Thanks,
:::::
:::::Dave...
::::::Hi Dave
::::::
:::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::::::
:::::: See if you can find any transformer with two secondary windings.
::::::
::::::Norm
::::::
:::::::Hi Norm,
::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::::::
:::::::Thanks very much,
:::::::
:::::::Dave...
::::::::Hi Dave
::::::::
:::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::::::
:::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::::::
::::::::Norm
::::::::
:::::::::Hello All,
::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::::::
:::::::::
:::::::::Thanks,
:::::::::
:::::::::Dave...
Ok on your 6L6's. Grid to cathode on a 6J5 will not be much but shouldn't be + .5 volts. Maybe cap #109 is leaky? I would replace this cap..
Norm
:Norm,
: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:
:Thanks,
:
::Dave
::
:: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::
::Norm
::
:::Norm,
::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::
:::Thanks,
:::
:::Dave...
::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::: Maybe there is a speacial way to connect the ends of the secondaries.
::::
::::Thanks,
::::
::::
:::::Dave
:::::
::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::
:::::Norm
:::::
::::::Norm,
:::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::
::::::Thanks,
::::::
::::::Dave...
:::::::Hi Dave
:::::::
::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::
::::::: See if you can find any transformer with two secondary windings.
:::::::
:::::::Norm
:::::::
::::::::Hi Norm,
:::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::
::::::::Thanks very much,
::::::::
::::::::Dave...
:::::::::Hi Dave
:::::::::
::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::
::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::
:::::::::Norm
:::::::::
::::::::::Hello All,
:::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::
::::::::::
::::::::::Thanks,
::::::::::
::::::::::Dave...
:Norm,
: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:
:Thanks,
:
::Dave
::
:: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::
::Norm
::
:::Norm,
::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::
:::Thanks,
:::
:::Dave...
::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::: Maybe there is a speacial way to connect the ends of the secondaries.
::::
::::Thanks,
::::
::::
:::::Dave
:::::
::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::
:::::Norm
:::::
::::::Norm,
:::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::
::::::Thanks,
::::::
::::::Dave...
:::::::Hi Dave
:::::::
::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::
::::::: See if you can find any transformer with two secondary windings.
:::::::
:::::::Norm
:::::::
::::::::Hi Norm,
:::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::
::::::::Thanks very much,
::::::::
::::::::Dave...
:::::::::Hi Dave
:::::::::
::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::
::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::
:::::::::Norm
:::::::::
::::::::::Hello All,
:::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::
::::::::::
::::::::::Thanks,
::::::::::
::::::::::Dave...
Thanks,
Dave...
:Also be sure resistor 114, 330K, hasn't gone up in value or opened..
:
::Norm,
:: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
::
::Thanks,
::
:::Dave
:::
::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
:::
:::Norm
:::
::::Norm,
:::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
::::
::::Thanks,
::::
::::Dave...
:::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
::::: Maybe there is a speacial way to connect the ends of the secondaries.
:::::
:::::Thanks,
:::::
:::::
::::::Dave
::::::
:::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
::::::
::::::Norm
::::::
:::::::Norm,
::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:::::::
:::::::Thanks,
:::::::
:::::::Dave...
::::::::Hi Dave
::::::::
:::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::::::::
:::::::: See if you can find any transformer with two secondary windings.
::::::::
::::::::Norm
::::::::
:::::::::Hi Norm,
::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::::::::
:::::::::Thanks very much,
:::::::::
:::::::::Dave...
::::::::::Hi Dave
::::::::::
:::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::::::::
:::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::::::::
::::::::::Norm
::::::::::
:::::::::::Hello All,
::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::::::::
:::::::::::
:::::::::::Thanks,
:::::::::::
:::::::::::Dave...
The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
Norm
:Norm,
:Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
:
:Thanks,
:
:Dave...
::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
::
:::Norm,
::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:::
:::Thanks,
:::
::::Dave
::::
:::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::::
::::Norm
::::
:::::Norm,
::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::::
:::::Thanks,
:::::
:::::Dave...
::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::::: Maybe there is a speacial way to connect the ends of the secondaries.
::::::
::::::Thanks,
::::::
::::::
:::::::Dave
:::::::
::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::::
:::::::Norm
:::::::
::::::::Norm,
:::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::::
::::::::Thanks,
::::::::
::::::::Dave...
:::::::::Hi Dave
:::::::::
::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::::
::::::::: See if you can find any transformer with two secondary windings.
:::::::::
:::::::::Norm
:::::::::
::::::::::Hi Norm,
:::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::::
::::::::::Thanks very much,
::::::::::
::::::::::Dave...
:::::::::::Hi Dave
:::::::::::
::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::::
::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::::
:::::::::::Norm
:::::::::::
::::::::::::Hello All,
:::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::::
::::::::::::
::::::::::::Thanks,
::::::::::::
::::::::::::Dave...
:Dave
:
: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
:
: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
:
:Norm
:
::Norm,
::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
::
::Thanks,
::
::Dave...
:::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
:::
::::Norm,
:::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
::::
::::Thanks,
::::
:::::Dave
:::::
::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
:::::
:::::Norm
:::::
::::::Norm,
:::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
::::::
::::::Thanks,
::::::
::::::Dave...
:::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
::::::: Maybe there is a speacial way to connect the ends of the secondaries.
:::::::
:::::::Thanks,
:::::::
:::::::
::::::::Dave
::::::::
:::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
::::::::
::::::::Norm
::::::::
:::::::::Norm,
::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:::::::::
:::::::::Thanks,
:::::::::
:::::::::Dave...
::::::::::Hi Dave
::::::::::
:::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::::::::::
:::::::::: See if you can find any transformer with two secondary windings.
::::::::::
::::::::::Norm
::::::::::
:::::::::::Hi Norm,
::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::::::::::
:::::::::::Thanks very much,
:::::::::::
:::::::::::Dave...
::::::::::::Hi Dave
::::::::::::
:::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::::::::::
:::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::::::::::
::::::::::::Norm
::::::::::::
:::::::::::::Hello All,
::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::::::::::
:::::::::::::
:::::::::::::Thanks,
:::::::::::::
:::::::::::::Dave...
:Dave
:
: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
:
: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
:
:Norm
:
::Norm,
::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
::
::Thanks,
::
::Dave...
:::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
:::
::::Norm,
:::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
::::
::::Thanks,
::::
:::::Dave
:::::
::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
:::::
:::::Norm
:::::
::::::Norm,
:::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
::::::
::::::Thanks,
::::::
::::::Dave...
:::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
::::::: Maybe there is a speacial way to connect the ends of the secondaries.
:::::::
:::::::Thanks,
:::::::
:::::::
::::::::Dave
::::::::
:::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
::::::::
::::::::Norm
::::::::
:::::::::Norm,
::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:::::::::
:::::::::Thanks,
:::::::::
:::::::::Dave...
::::::::::Hi Dave
::::::::::
:::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::::::::::
:::::::::: See if you can find any transformer with two secondary windings.
::::::::::
::::::::::Norm
::::::::::
:::::::::::Hi Norm,
::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::::::::::
:::::::::::Thanks very much,
:::::::::::
:::::::::::Dave...
::::::::::::Hi Dave
::::::::::::
:::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::::::::::
:::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::::::::::
::::::::::::Norm
::::::::::::
:::::::::::::Hello All,
::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::::::::::
:::::::::::::
:::::::::::::Thanks,
:::::::::::::
:::::::::::::Dave...
Thanks,
Dave...
:Norm,
: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
:
::Dave
::
:: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
::
:: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
::
::Norm
::
:::Norm,
:::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
:::
:::Thanks,
:::
:::Dave...
::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
::::
:::::Norm,
::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:::::
:::::Thanks,
:::::
::::::Dave
::::::
:::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::::::
::::::Norm
::::::
:::::::Norm,
::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::::::
:::::::Thanks,
:::::::
:::::::Dave...
::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::::::: Maybe there is a speacial way to connect the ends of the secondaries.
::::::::
::::::::Thanks,
::::::::
::::::::
:::::::::Dave
:::::::::
::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::::::
:::::::::Norm
:::::::::
::::::::::Norm,
:::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::::::
::::::::::Thanks,
::::::::::
::::::::::Dave...
:::::::::::Hi Dave
:::::::::::
::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::::::
::::::::::: See if you can find any transformer with two secondary windings.
:::::::::::
:::::::::::Norm
:::::::::::
::::::::::::Hi Norm,
:::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::::::
::::::::::::Thanks very much,
::::::::::::
::::::::::::Dave...
:::::::::::::Hi Dave
:::::::::::::
::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::::::
::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::::::
:::::::::::::Norm
:::::::::::::
::::::::::::::Hello All,
:::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::::::
::::::::::::::
::::::::::::::Thanks,
::::::::::::::
::::::::::::::Dave...
Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
Norm
:
:Norm,
: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
:
:Thanks,
:
:Dave...
:
::Norm,
:: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
::
:::Dave
:::
::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
:::
::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
:::
:::Norm
:::
::::Norm,
::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
::::
::::Thanks,
::::
::::Dave...
:::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
:::::
::::::Norm,
:::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
::::::
::::::Thanks,
::::::
:::::::Dave
:::::::
::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
:::::::
:::::::Norm
:::::::
::::::::Norm,
:::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
::::::::
::::::::Thanks,
::::::::
::::::::Dave...
:::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
:::::::::
:::::::::Thanks,
:::::::::
:::::::::
::::::::::Dave
::::::::::
:::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
::::::::::
::::::::::Norm
::::::::::
:::::::::::Norm,
::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:::::::::::
:::::::::::Thanks,
:::::::::::
:::::::::::Dave...
::::::::::::Hi Dave
::::::::::::
:::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::::::::::::
:::::::::::: See if you can find any transformer with two secondary windings.
::::::::::::
::::::::::::Norm
::::::::::::
:::::::::::::Hi Norm,
::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::::::::::::
:::::::::::::Thanks very much,
:::::::::::::
:::::::::::::Dave...
::::::::::::::Hi Dave
::::::::::::::
:::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::::::::::::
:::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::::::::::::
::::::::::::::Norm
::::::::::::::
:::::::::::::::Hello All,
::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::::::::::::
:::::::::::::::
:::::::::::::::Thanks,
:::::::::::::::
:::::::::::::::Dave...
Thanks,
Dave...
:Dave
:
: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
:
: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
:
:Norm
:
::
:
:
:
::Norm,
:: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
::
::Thanks,
::
::Dave...
::
:::Norm,
::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
:::
::::Dave
::::
:::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
::::
:::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
::::
::::Norm
::::
:::::Norm,
:::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
:::::
:::::Thanks,
:::::
:::::Dave...
::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
::::::
:::::::Norm,
::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:::::::
:::::::Thanks,
:::::::
::::::::Dave
::::::::
:::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::::::::
::::::::Norm
::::::::
:::::::::Norm,
::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::::::::
:::::::::Thanks,
:::::::::
:::::::::Dave...
::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
::::::::::
::::::::::Thanks,
::::::::::
::::::::::
:::::::::::Dave
:::::::::::
::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::::::::
:::::::::::Norm
:::::::::::
::::::::::::Norm,
:::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::::::::
::::::::::::Thanks,
::::::::::::
::::::::::::Dave...
:::::::::::::Hi Dave
:::::::::::::
::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::::::::
::::::::::::: See if you can find any transformer with two secondary windings.
:::::::::::::
:::::::::::::Norm
:::::::::::::
::::::::::::::Hi Norm,
:::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::::::::
::::::::::::::Thanks very much,
::::::::::::::
::::::::::::::Dave...
:::::::::::::::Hi Dave
:::::::::::::::
::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::::::::
::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
::::::::::::::::Hello All,
:::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::::::::
::::::::::::::::
::::::::::::::::Thanks,
::::::::::::::::
::::::::::::::::Dave...
Dave...
:The speaker is fine. I even tried another speaker and it does the same thing. The field coil is powered up and the plates of the 6L6s are the correct voltage too. So the speaker transformer is good too. The 6L6s test good.
: I'll now check the voltages on the 6R7G (none of the resistors are open there either).
: As I already said, between grid and cathode on the 6J5 driver tube I have .5 volts (now it's .48 volts) , not 3. On the 6R7 I have 2.0 volts between grid and cathode (negative meter lead is on the grid). Where could the missing voltage be on the 6J5? All resistors are good. I removed them from the circuit and they are good. I used a 390K resistor to replace the 350 which had drifted to about 600K. I don't have a 350K. I have a 330 K. An open resistor has to be somewhere. But I don't see any. Neither of the chokes is open either. Where should I look next? The 6J5 tests good.
:
:Thanks,
:
:Dave...
::Dave
::
:: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
::
:: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
::
::Norm
::
:::
::
::
::
:::Norm,
::: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
:::
:::Thanks,
:::
:::Dave...
:::
::::Norm,
:::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
::::
:::::Dave
:::::
::::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
:::::
::::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
:::::
:::::Norm
:::::
::::::Norm,
::::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
::::::
::::::Thanks,
::::::
::::::Dave...
:::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
:::::::
::::::::Norm,
:::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
::::::::
::::::::Thanks,
::::::::
:::::::::Dave
:::::::::
::::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
:::::::::
:::::::::Norm
:::::::::
::::::::::Norm,
:::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
::::::::::
::::::::::Thanks,
::::::::::
::::::::::Dave...
:::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
::::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
:::::::::::
:::::::::::Thanks,
:::::::::::
:::::::::::
::::::::::::Dave
::::::::::::
:::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
::::::::::::
::::::::::::Norm
::::::::::::
:::::::::::::Norm,
::::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
::::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:::::::::::::
:::::::::::::Thanks,
:::::::::::::
:::::::::::::Dave...
::::::::::::::Hi Dave
::::::::::::::
:::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::::::::::::::
:::::::::::::: See if you can find any transformer with two secondary windings.
::::::::::::::
::::::::::::::Norm
::::::::::::::
:::::::::::::::Hi Norm,
::::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::::::::::::::
:::::::::::::::Thanks very much,
:::::::::::::::
:::::::::::::::Dave...
::::::::::::::::Hi Dave
::::::::::::::::
:::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::::::::::::::
:::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::::::::::::::
::::::::::::::::Norm
::::::::::::::::
:::::::::::::::::Hello All,
::::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::::::::::::::
:::::::::::::::::
:::::::::::::::::Thanks,
:::::::::::::::::
:::::::::::::::::Dave...
Now that I am using the same print it might help.. Has cap #79 been replaced and does it have leakage? What voltage do you have between #110 & #111, bottom of schematic. This is where negative grid voltage is generated. Your tube should have this same voltage (pin #5) but a meter may load it down.
Exact resistor value wouldn't matter. Being open or very high would be a problem. 390K is ok.
Norm
:The speaker is fine. I even tried another speaker and it does the same thing. The field coil is powered up and the plates of the 6L6s are the correct voltage too. So the speaker transformer is good too. The 6L6s test good.
: I'll now check the voltages on the 6R7G (none of the resistors are open there either).
: As I already said, between grid and cathode on the 6J5 driver tube I have .5 volts (now it's .48 volts) , not 3. On the 6R7 I have 2.0 volts between grid and cathode (negative meter lead is on the grid). Where could the missing voltage be on the 6J5? All resistors are good. I removed them from the circuit and they are good. I used a 390K resistor to replace the 350 which had drifted to about 600K. I don't have a 350K. I have a 330 K. An open resistor has to be somewhere. But I don't see any. Neither of the chokes is open either. Where should I look next? The 6J5 tests good.
:
:Thanks,
:
:Dave...
::Dave
::
:: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
::
:: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
::
::Norm
::
:::
::
::
::
:::Norm,
::: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
:::
:::Thanks,
:::
:::Dave...
:::
::::Norm,
:::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
::::
:::::Dave
:::::
::::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
:::::
::::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
:::::
:::::Norm
:::::
::::::Norm,
::::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
::::::
::::::Thanks,
::::::
::::::Dave...
:::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
:::::::
::::::::Norm,
:::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
::::::::
::::::::Thanks,
::::::::
:::::::::Dave
:::::::::
::::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
:::::::::
:::::::::Norm
:::::::::
::::::::::Norm,
:::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
::::::::::
::::::::::Thanks,
::::::::::
::::::::::Dave...
:::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
::::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
:::::::::::
:::::::::::Thanks,
:::::::::::
:::::::::::
::::::::::::Dave
::::::::::::
:::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
::::::::::::
::::::::::::Norm
::::::::::::
:::::::::::::Norm,
::::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
::::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:::::::::::::
:::::::::::::Thanks,
:::::::::::::
:::::::::::::Dave...
::::::::::::::Hi Dave
::::::::::::::
:::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::::::::::::::
:::::::::::::: See if you can find any transformer with two secondary windings.
::::::::::::::
::::::::::::::Norm
::::::::::::::
:::::::::::::::Hi Norm,
::::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::::::::::::::
:::::::::::::::Thanks very much,
:::::::::::::::
:::::::::::::::Dave...
::::::::::::::::Hi Dave
::::::::::::::::
:::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::::::::::::::
:::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::::::::::::::
::::::::::::::::Norm
::::::::::::::::
:::::::::::::::::Hello All,
::::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::::::::::::::
:::::::::::::::::
:::::::::::::::::Thanks,
:::::::::::::::::
:::::::::::::::::Dave...
Thanks very much,
:Dave
:
: Now that I am using the same print it might help.. Has cap #79 been replaced and does it have leakage? What voltage do you have between #110 & #111, bottom of schematic. This is where negative grid voltage is generated. Your tube should have this same voltage (pin #5) but a meter may load it down.
:
: Exact resistor value wouldn't matter. Being open or very high would be a problem. 390K is ok.
:
:Norm
:
::The speaker is fine. I even tried another speaker and it does the same thing. The field coil is powered up and the plates of the 6L6s are the correct voltage too. So the speaker transformer is good too. The 6L6s test good.
:: I'll now check the voltages on the 6R7G (none of the resistors are open there either).
:: As I already said, between grid and cathode on the 6J5 driver tube I have .5 volts (now it's .48 volts) , not 3. On the 6R7 I have 2.0 volts between grid and cathode (negative meter lead is on the grid). Where could the missing voltage be on the 6J5? All resistors are good. I removed them from the circuit and they are good. I used a 390K resistor to replace the 350 which had drifted to about 600K. I don't have a 350K. I have a 330 K. An open resistor has to be somewhere. But I don't see any. Neither of the chokes is open either. Where should I look next? The 6J5 tests good.
::
::Thanks,
::
::Dave...
:::Dave
:::
::: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
:::
::: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
:::
:::Norm
:::
::::
:::
:::
:::
::::Norm,
:::: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
::::
::::Thanks,
::::
::::Dave...
::::
:::::Norm,
::::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
:::::
::::::Dave
::::::
:::::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
::::::
:::::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
::::::
::::::Norm
::::::
:::::::Norm,
:::::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
:::::::
:::::::Thanks,
:::::::
:::::::Dave...
::::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
::::::::
:::::::::Norm,
::::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:::::::::
:::::::::Thanks,
:::::::::
::::::::::Dave
::::::::::
:::::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::::::::::
::::::::::Norm
::::::::::
:::::::::::Norm,
::::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::::::::::
:::::::::::Thanks,
:::::::::::
:::::::::::Dave...
::::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
::::::::::::
::::::::::::Thanks,
::::::::::::
::::::::::::
:::::::::::::Dave
:::::::::::::
::::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::::::::::
:::::::::::::Norm
:::::::::::::
::::::::::::::Norm,
:::::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::::::::::
::::::::::::::Thanks,
::::::::::::::
::::::::::::::Dave...
:::::::::::::::Hi Dave
:::::::::::::::
::::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::::::::::
::::::::::::::: See if you can find any transformer with two secondary windings.
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
::::::::::::::::Hi Norm,
:::::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::::::::::
::::::::::::::::Thanks very much,
::::::::::::::::
::::::::::::::::Dave...
:::::::::::::::::Hi Dave
:::::::::::::::::
::::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::::::::::
::::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::::::::::
:::::::::::::::::Norm
:::::::::::::::::
::::::::::::::::::Hello All,
:::::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::::::::::
::::::::::::::::::
::::::::::::::::::Thanks,
::::::::::::::::::
::::::::::::::::::Dave...
Thanks,
Dave...
:Norm,
: I discovered something very interesting. One end of 94 does connect to the grid of the 6J5 but the other end was not connected to the junction between 109 and 110 (I didn't do this. This is how it was). It was connected to the junction of 83 and 84 instead. When I connected it to where it should go, the distortion was greatly reduced and the volume was greatly increased. I still have no tone control at all. The voltage at the point where 110 and 111 attach is 2.2 volts. The voltage between power supply negative and the chassis is 59 volts (negative lead on power supply negative). I still have no low frequencies and the tone control seems to do nothing.
: So this has lead to another problem. But I think that the missing grid voltage has been found.
: Please continue to help me find the missing low frequencies.
:
:Thanks very much,
:
:
::Dave
::
:: Now that I am using the same print it might help.. Has cap #79 been replaced and does it have leakage? What voltage do you have between #110 & #111, bottom of schematic. This is where negative grid voltage is generated. Your tube should have this same voltage (pin #5) but a meter may load it down.
::
:: Exact resistor value wouldn't matter. Being open or very high would be a problem. 390K is ok.
::
::Norm
::
:::The speaker is fine. I even tried another speaker and it does the same thing. The field coil is powered up and the plates of the 6L6s are the correct voltage too. So the speaker transformer is good too. The 6L6s test good.
::: I'll now check the voltages on the 6R7G (none of the resistors are open there either).
::: As I already said, between grid and cathode on the 6J5 driver tube I have .5 volts (now it's .48 volts) , not 3. On the 6R7 I have 2.0 volts between grid and cathode (negative meter lead is on the grid). Where could the missing voltage be on the 6J5? All resistors are good. I removed them from the circuit and they are good. I used a 390K resistor to replace the 350 which had drifted to about 600K. I don't have a 350K. I have a 330 K. An open resistor has to be somewhere. But I don't see any. Neither of the chokes is open either. Where should I look next? The 6J5 tests good.
:::
:::Thanks,
:::
:::Dave...
::::Dave
::::
:::: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
::::
:::: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
::::
::::Norm
::::
:::::
::::
::::
::::
:::::Norm,
::::: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
:::::
:::::Thanks,
:::::
:::::Dave...
:::::
::::::Norm,
:::::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
::::::
:::::::Dave
:::::::
::::::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
:::::::
::::::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
:::::::
:::::::Norm
:::::::
::::::::Norm,
::::::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
::::::::
::::::::Thanks,
::::::::
::::::::Dave...
:::::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
:::::::::
::::::::::Norm,
:::::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
::::::::::
::::::::::Thanks,
::::::::::
:::::::::::Dave
:::::::::::
::::::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
:::::::::::
:::::::::::Norm
:::::::::::
::::::::::::Norm,
:::::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
::::::::::::
::::::::::::Thanks,
::::::::::::
::::::::::::Dave...
:::::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
::::::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
:::::::::::::
:::::::::::::Thanks,
:::::::::::::
:::::::::::::
::::::::::::::Dave
::::::::::::::
:::::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
::::::::::::::
::::::::::::::Norm
::::::::::::::
:::::::::::::::Norm,
::::::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
::::::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:::::::::::::::
:::::::::::::::Thanks,
:::::::::::::::
:::::::::::::::Dave...
::::::::::::::::Hi Dave
::::::::::::::::
:::::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::::::::::::::::
:::::::::::::::: See if you can find any transformer with two secondary windings.
::::::::::::::::
::::::::::::::::Norm
::::::::::::::::
:::::::::::::::::Hi Norm,
::::::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::::::::::::::::
:::::::::::::::::Thanks very much,
:::::::::::::::::
:::::::::::::::::Dave...
::::::::::::::::::Hi Dave
::::::::::::::::::
:::::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::::::::::::::::
:::::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::::::::::::::::
::::::::::::::::::Norm
::::::::::::::::::
:::::::::::::::::::Hello All,
::::::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::::::::::::::::
:::::::::::::::::::
:::::::::::::::::::Thanks,
:::::::::::::::::::
:::::::::::::::::::Dave...
Minus 7 volts is ok. I wanted to be sure it was several volts negative. That's ok on a 6J5 tube.
Tone control is a large cap, .02, #93. It's added in by adjusting the control. Does this control have a problem? An easy way to find out, connect a .02 mfd cap from the place where it attaches and ground while the radio is operating. See if you hear a difference.
That .004 mfd coupling cap, to 6J5G, seems small to me but that's what's in the schematic. Be sure it isn't less.
Hard for me to get an exact understanding over the internet. Connecting a scope on the output and using an audio signal generator would help but probably not available?
Norm
:Norm,
: I don't think that that's right either because now the grid is at minus 7 volts, which is too high. You had said -2 volts is correct. So I better see what other mistakes someone made before I got this set. I am measuring between the grid of the driver 6J5 and the chassis, with the positive on the grid and the negative lead on the chassis. This gives me a reading of -7 volts.
:
:Thanks,
:
:Dave...
::Norm,
:: I discovered something very interesting. One end of 94 does connect to the grid of the 6J5 but the other end was not connected to the junction between 109 and 110 (I didn't do this. This is how it was). It was connected to the junction of 83 and 84 instead. When I connected it to where it should go, the distortion was greatly reduced and the volume was greatly increased. I still have no tone control at all. The voltage at the point where 110 and 111 attach is 2.2 volts. The voltage between power supply negative and the chassis is 59 volts (negative lead on power supply negative). I still have no low frequencies and the tone control seems to do nothing.
:: So this has lead to another problem. But I think that the missing grid voltage has been found.
:: Please continue to help me find the missing low frequencies.
::
::Thanks very much,
::
::
:::Dave
:::
::: Now that I am using the same print it might help.. Has cap #79 been replaced and does it have leakage? What voltage do you have between #110 & #111, bottom of schematic. This is where negative grid voltage is generated. Your tube should have this same voltage (pin #5) but a meter may load it down.
:::
::: Exact resistor value wouldn't matter. Being open or very high would be a problem. 390K is ok.
:::
:::Norm
:::
::::The speaker is fine. I even tried another speaker and it does the same thing. The field coil is powered up and the plates of the 6L6s are the correct voltage too. So the speaker transformer is good too. The 6L6s test good.
:::: I'll now check the voltages on the 6R7G (none of the resistors are open there either).
:::: As I already said, between grid and cathode on the 6J5 driver tube I have .5 volts (now it's .48 volts) , not 3. On the 6R7 I have 2.0 volts between grid and cathode (negative meter lead is on the grid). Where could the missing voltage be on the 6J5? All resistors are good. I removed them from the circuit and they are good. I used a 390K resistor to replace the 350 which had drifted to about 600K. I don't have a 350K. I have a 330 K. An open resistor has to be somewhere. But I don't see any. Neither of the chokes is open either. Where should I look next? The 6J5 tests good.
::::
::::Thanks,
::::
::::Dave...
:::::Dave
:::::
::::: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
:::::
::::: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
:::::
:::::Norm
:::::
::::::
:::::
:::::
:::::
::::::Norm,
:::::: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
::::::
::::::Thanks,
::::::
::::::Dave...
::::::
:::::::Norm,
::::::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
:::::::
::::::::Dave
::::::::
:::::::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
::::::::
:::::::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
::::::::
::::::::Norm
::::::::
:::::::::Norm,
:::::::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
:::::::::
:::::::::Thanks,
:::::::::
:::::::::Dave...
::::::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
::::::::::
:::::::::::Norm,
::::::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:::::::::::
:::::::::::Thanks,
:::::::::::
::::::::::::Dave
::::::::::::
:::::::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::::::::::::
::::::::::::Norm
::::::::::::
:::::::::::::Norm,
::::::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::::::::::::
:::::::::::::Thanks,
:::::::::::::
:::::::::::::Dave...
::::::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::::::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
::::::::::::::
::::::::::::::Thanks,
::::::::::::::
::::::::::::::
:::::::::::::::Dave
:::::::::::::::
::::::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
::::::::::::::::Norm,
:::::::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::::::::::::
::::::::::::::::Thanks,
::::::::::::::::
::::::::::::::::Dave...
:::::::::::::::::Hi Dave
:::::::::::::::::
::::::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::::::::::::
::::::::::::::::: See if you can find any transformer with two secondary windings.
:::::::::::::::::
:::::::::::::::::Norm
:::::::::::::::::
::::::::::::::::::Hi Norm,
:::::::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::::::::::::
::::::::::::::::::Thanks very much,
::::::::::::::::::
::::::::::::::::::Dave...
:::::::::::::::::::Hi Dave
:::::::::::::::::::
::::::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::::::::::::
::::::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::::::::::::
:::::::::::::::::::Norm
:::::::::::::::::::
::::::::::::::::::::Hello All,
:::::::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::::::::::::
::::::::::::::::::::
::::::::::::::::::::Thanks,
::::::::::::::::::::
::::::::::::::::::::Dave...
:Dave
:
: Minus 7 volts is ok. I wanted to be sure it was several volts negative. That's ok on a 6J5 tube.
:
: Tone control is a large cap, .02, #93. It's added in by adjusting the control. Does this control have a problem? An easy way to find out, connect a .02 mfd cap from the place where it attaches and ground while the radio is operating. See if you hear a difference.
:
: That .004 mfd coupling cap, to 6J5G, seems small to me but that's what's in the schematic. Be sure it isn't less.
:
: Hard for me to get an exact understanding over the internet. Connecting a scope on the output and using an audio signal generator would help but probably not available?
:
:Norm
:
:
:
:
:
::Norm,
:: I don't think that that's right either because now the grid is at minus 7 volts, which is too high. You had said -2 volts is correct. So I better see what other mistakes someone made before I got this set. I am measuring between the grid of the driver 6J5 and the chassis, with the positive on the grid and the negative lead on the chassis. This gives me a reading of -7 volts.
::
::Thanks,
::
::Dave...
:::Norm,
::: I discovered something very interesting. One end of 94 does connect to the grid of the 6J5 but the other end was not connected to the junction between 109 and 110 (I didn't do this. This is how it was). It was connected to the junction of 83 and 84 instead. When I connected it to where it should go, the distortion was greatly reduced and the volume was greatly increased. I still have no tone control at all. The voltage at the point where 110 and 111 attach is 2.2 volts. The voltage between power supply negative and the chassis is 59 volts (negative lead on power supply negative). I still have no low frequencies and the tone control seems to do nothing.
::: So this has lead to another problem. But I think that the missing grid voltage has been found.
::: Please continue to help me find the missing low frequencies.
:::
:::Thanks very much,
:::
:::
::::Dave
::::
:::: Now that I am using the same print it might help.. Has cap #79 been replaced and does it have leakage? What voltage do you have between #110 & #111, bottom of schematic. This is where negative grid voltage is generated. Your tube should have this same voltage (pin #5) but a meter may load it down.
::::
:::: Exact resistor value wouldn't matter. Being open or very high would be a problem. 390K is ok.
::::
::::Norm
::::
:::::The speaker is fine. I even tried another speaker and it does the same thing. The field coil is powered up and the plates of the 6L6s are the correct voltage too. So the speaker transformer is good too. The 6L6s test good.
::::: I'll now check the voltages on the 6R7G (none of the resistors are open there either).
::::: As I already said, between grid and cathode on the 6J5 driver tube I have .5 volts (now it's .48 volts) , not 3. On the 6R7 I have 2.0 volts between grid and cathode (negative meter lead is on the grid). Where could the missing voltage be on the 6J5? All resistors are good. I removed them from the circuit and they are good. I used a 390K resistor to replace the 350 which had drifted to about 600K. I don't have a 350K. I have a 330 K. An open resistor has to be somewhere. But I don't see any. Neither of the chokes is open either. Where should I look next? The 6J5 tests good.
:::::
:::::Thanks,
:::::
:::::Dave...
::::::Dave
::::::
:::::: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
::::::
:::::: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
::::::
::::::Norm
::::::
:::::::
::::::
::::::
::::::
:::::::Norm,
::::::: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
:::::::
:::::::Thanks,
:::::::
:::::::Dave...
:::::::
::::::::Norm,
:::::::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
::::::::
:::::::::Dave
:::::::::
::::::::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
:::::::::
::::::::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
:::::::::
:::::::::Norm
:::::::::
::::::::::Norm,
::::::::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
::::::::::
::::::::::Thanks,
::::::::::
::::::::::Dave...
:::::::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
:::::::::::
::::::::::::Norm,
:::::::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
::::::::::::
::::::::::::Thanks,
::::::::::::
:::::::::::::Dave
:::::::::::::
::::::::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
:::::::::::::
:::::::::::::Norm
:::::::::::::
::::::::::::::Norm,
:::::::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
::::::::::::::
::::::::::::::Thanks,
::::::::::::::
::::::::::::::Dave...
:::::::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
::::::::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
:::::::::::::::
:::::::::::::::Thanks,
:::::::::::::::
:::::::::::::::
::::::::::::::::Dave
::::::::::::::::
:::::::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
::::::::::::::::
::::::::::::::::Norm
::::::::::::::::
:::::::::::::::::Norm,
::::::::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
::::::::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
:::::::::::::::::
:::::::::::::::::Thanks,
:::::::::::::::::
:::::::::::::::::Dave...
::::::::::::::::::Hi Dave
::::::::::::::::::
:::::::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
::::::::::::::::::
:::::::::::::::::: See if you can find any transformer with two secondary windings.
::::::::::::::::::
::::::::::::::::::Norm
::::::::::::::::::
:::::::::::::::::::Hi Norm,
::::::::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
:::::::::::::::::::
:::::::::::::::::::Thanks very much,
:::::::::::::::::::
:::::::::::::::::::Dave...
::::::::::::::::::::Hi Dave
::::::::::::::::::::
:::::::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
::::::::::::::::::::
:::::::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
::::::::::::::::::::
::::::::::::::::::::Norm
::::::::::::::::::::
:::::::::::::::::::::Hello All,
::::::::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
::::::::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
:::::::::::::::::::::
:::::::::::::::::::::
:::::::::::::::::::::Thanks,
:::::::::::::::::::::
:::::::::::::::::::::Dave...
Increasing the size of coupling caps will improve low frequency response. The schematic calls out .004 mfd coupling. Try a larger value.
See what information Rick sent you. It may take care of the problem?
AVC may not be working? This will cause overloading. AVC is a voltage which goes negative on strong stations cutting back gain. It's controls RF & IF tube grids.
Norm
:Norm,
: I'm very happy that the first problem is solved. Now that I can hear the radio, I see that it tunes fine. I'm not sure how that automatic tuning is set. I'm not sure what Magnetic tuning is. Some how a discriminator is used and an IF Expander is used too. Is the AM converted to FM? It seems to receive ok.
: I have a scope. I have an audio generator somewhere around here. It sounds like the pre-amp is overloading the amplifier stage. Too loud for it. Kind of like over exposed film. Plus there's no bass response. There is plenty of upper range. But the low is gone. It's too flat sounding. How can I boost the bass? This set was known to have a very good tone to in and right now it sounds tinny.
:
:Thanks,
:
::Dave
::
:: Minus 7 volts is ok. I wanted to be sure it was several volts negative. That's ok on a 6J5 tube.
::
:: Tone control is a large cap, .02, #93. It's added in by adjusting the control. Does this control have a problem? An easy way to find out, connect a .02 mfd cap from the place where it attaches and ground while the radio is operating. See if you hear a difference.
::
:: That .004 mfd coupling cap, to 6J5G, seems small to me but that's what's in the schematic. Be sure it isn't less.
::
:: Hard for me to get an exact understanding over the internet. Connecting a scope on the output and using an audio signal generator would help but probably not available?
::
::Norm
::
::
::
::
::
:::Norm,
::: I don't think that that's right either because now the grid is at minus 7 volts, which is too high. You had said -2 volts is correct. So I better see what other mistakes someone made before I got this set. I am measuring between the grid of the driver 6J5 and the chassis, with the positive on the grid and the negative lead on the chassis. This gives me a reading of -7 volts.
:::
:::Thanks,
:::
:::Dave...
::::Norm,
:::: I discovered something very interesting. One end of 94 does connect to the grid of the 6J5 but the other end was not connected to the junction between 109 and 110 (I didn't do this. This is how it was). It was connected to the junction of 83 and 84 instead. When I connected it to where it should go, the distortion was greatly reduced and the volume was greatly increased. I still have no tone control at all. The voltage at the point where 110 and 111 attach is 2.2 volts. The voltage between power supply negative and the chassis is 59 volts (negative lead on power supply negative). I still have no low frequencies and the tone control seems to do nothing.
:::: So this has lead to another problem. But I think that the missing grid voltage has been found.
:::: Please continue to help me find the missing low frequencies.
::::
::::Thanks very much,
::::
::::
:::::Dave
:::::
::::: Now that I am using the same print it might help.. Has cap #79 been replaced and does it have leakage? What voltage do you have between #110 & #111, bottom of schematic. This is where negative grid voltage is generated. Your tube should have this same voltage (pin #5) but a meter may load it down.
:::::
::::: Exact resistor value wouldn't matter. Being open or very high would be a problem. 390K is ok.
:::::
:::::Norm
:::::
::::::The speaker is fine. I even tried another speaker and it does the same thing. The field coil is powered up and the plates of the 6L6s are the correct voltage too. So the speaker transformer is good too. The 6L6s test good.
:::::: I'll now check the voltages on the 6R7G (none of the resistors are open there either).
:::::: As I already said, between grid and cathode on the 6J5 driver tube I have .5 volts (now it's .48 volts) , not 3. On the 6R7 I have 2.0 volts between grid and cathode (negative meter lead is on the grid). Where could the missing voltage be on the 6J5? All resistors are good. I removed them from the circuit and they are good. I used a 390K resistor to replace the 350 which had drifted to about 600K. I don't have a 350K. I have a 330 K. An open resistor has to be somewhere. But I don't see any. Neither of the chokes is open either. Where should I look next? The 6J5 tests good.
::::::
::::::Thanks,
::::::
::::::Dave...
:::::::Dave
:::::::
::::::: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
:::::::
::::::: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
:::::::
:::::::Norm
:::::::
::::::::
:::::::
:::::::
:::::::
::::::::Norm,
:::::::: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
::::::::
::::::::Thanks,
::::::::
::::::::Dave...
::::::::
:::::::::Norm,
::::::::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
:::::::::
::::::::::Dave
::::::::::
:::::::::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
::::::::::
:::::::::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
::::::::::
::::::::::Norm
::::::::::
:::::::::::Norm,
:::::::::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
:::::::::::
:::::::::::Thanks,
:::::::::::
:::::::::::Dave...
::::::::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
::::::::::::
:::::::::::::Norm,
::::::::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:::::::::::::
:::::::::::::Thanks,
:::::::::::::
::::::::::::::Dave
::::::::::::::
:::::::::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::::::::::::::
::::::::::::::Norm
::::::::::::::
:::::::::::::::Norm,
::::::::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::::::::::::::
:::::::::::::::Thanks,
:::::::::::::::
:::::::::::::::Dave...
::::::::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::::::::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
::::::::::::::::
::::::::::::::::Thanks,
::::::::::::::::
::::::::::::::::
:::::::::::::::::Dave
:::::::::::::::::
::::::::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::::::::::::::
:::::::::::::::::Norm
:::::::::::::::::
::::::::::::::::::Norm,
:::::::::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::::::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::::::::::::::
::::::::::::::::::Thanks,
::::::::::::::::::
::::::::::::::::::Dave...
:::::::::::::::::::Hi Dave
:::::::::::::::::::
::::::::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::::::::::::::
::::::::::::::::::: See if you can find any transformer with two secondary windings.
:::::::::::::::::::
:::::::::::::::::::Norm
:::::::::::::::::::
::::::::::::::::::::Hi Norm,
:::::::::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::::::::::::::
::::::::::::::::::::Thanks very much,
::::::::::::::::::::
::::::::::::::::::::Dave...
:::::::::::::::::::::Hi Dave
:::::::::::::::::::::
::::::::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::::::::::::::
::::::::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::::::::::::::
:::::::::::::::::::::Norm
:::::::::::::::::::::
::::::::::::::::::::::Hello All,
:::::::::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::::::::::::::
::::::::::::::::::::::
::::::::::::::::::::::Thanks,
::::::::::::::::::::::
::::::::::::::::::::::Dave...
Thanks Again,
Dave...
::Norm,
:: It still sounds as if the 6L6 are being overloaded by this input transformer. Whether the tone control worked or not, there should be a lot more in the way of low frequencies here. It does still distort but its an overload type distortion and not the clipping sounds as I was getting before.
:: There's plenty more volume too. But it still doesn't sound right.
::
:::Dave
:::
::: Now that I am using the same print it might help.. Has cap #79 been replaced and does it have leakage? What voltage do you have between #110 & #111, bottom of schematic. This is where negative grid voltage is generated. Your tube should have this same voltage (pin #5) but a meter may load it down.
:::
::: Exact resistor value wouldn't matter. Being open or very high would be a problem. 390K is ok.
:::
:::Norm
:::
::::The speaker is fine. I even tried another speaker and it does the same thing. The field coil is powered up and the plates of the 6L6s are the correct voltage too. So the speaker transformer is good too. The 6L6s test good.
:::: I'll now check the voltages on the 6R7G (none of the resistors are open there either).
:::: As I already said, between grid and cathode on the 6J5 driver tube I have .5 volts (now it's .48 volts) , not 3. On the 6R7 I have 2.0 volts between grid and cathode (negative meter lead is on the grid). Where could the missing voltage be on the 6J5? All resistors are good. I removed them from the circuit and they are good. I used a 390K resistor to replace the 350 which had drifted to about 600K. I don't have a 350K. I have a 330 K. An open resistor has to be somewhere. But I don't see any. Neither of the chokes is open either. Where should I look next? The 6J5 tests good.
::::
::::Thanks,
::::
::::Dave...
:::::Dave
:::::
::::: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
:::::
::::: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
:::::
:::::Norm
:::::
::::::
:::::
:::::
:::::
::::::Norm,
:::::: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
::::::
::::::Thanks,
::::::
::::::Dave...
::::::
:::::::Norm,
::::::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
:::::::
::::::::Dave
::::::::
:::::::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
::::::::
:::::::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
::::::::
::::::::Norm
::::::::
:::::::::Norm,
:::::::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
:::::::::
:::::::::Thanks,
:::::::::
:::::::::Dave...
::::::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
::::::::::
:::::::::::Norm,
::::::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:::::::::::
:::::::::::Thanks,
:::::::::::
::::::::::::Dave
::::::::::::
:::::::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::::::::::::
::::::::::::Norm
::::::::::::
:::::::::::::Norm,
::::::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::::::::::::
:::::::::::::Thanks,
:::::::::::::
:::::::::::::Dave...
::::::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::::::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
::::::::::::::
::::::::::::::Thanks,
::::::::::::::
::::::::::::::
:::::::::::::::Dave
:::::::::::::::
::::::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
::::::::::::::::Norm,
:::::::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::::::::::::
::::::::::::::::Thanks,
::::::::::::::::
::::::::::::::::Dave...
:::::::::::::::::Hi Dave
:::::::::::::::::
::::::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::::::::::::
::::::::::::::::: See if you can find any transformer with two secondary windings.
:::::::::::::::::
:::::::::::::::::Norm
:::::::::::::::::
::::::::::::::::::Hi Norm,
:::::::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::::::::::::
::::::::::::::::::Thanks very much,
::::::::::::::::::
::::::::::::::::::Dave...
:::::::::::::::::::Hi Dave
:::::::::::::::::::
::::::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::::::::::::
::::::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::::::::::::
:::::::::::::::::::Norm
:::::::::::::::::::
::::::::::::::::::::Hello All,
:::::::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::::::::::::
::::::::::::::::::::
::::::::::::::::::::Thanks,
::::::::::::::::::::
::::::::::::::::::::Dave...
:
:Have sent PHILCO service bulletin 273 for the dial
:and 286A for the chassis code 125
Have sent PHILCO service bulletin 273 for the dial
and 286A for the chassis code 125
Thanks Again,
Dave...
::Norm,
:: It still sounds as if the 6L6 are being overloaded by this input transformer. Whether the tone control worked or not, there should be a lot more in the way of low frequencies here. It does still distort but its an overload type distortion and not the clipping sounds as I was getting before.
:: There's plenty more volume too. But it still doesn't sound right.
::
:::Dave
:::
::: Now that I am using the same print it might help.. Has cap #79 been replaced and does it have leakage? What voltage do you have between #110 & #111, bottom of schematic. This is where negative grid voltage is generated. Your tube should have this same voltage (pin #5) but a meter may load it down.
:::
::: Exact resistor value wouldn't matter. Being open or very high would be a problem. 390K is ok.
:::
:::Norm
:::
::::The speaker is fine. I even tried another speaker and it does the same thing. The field coil is powered up and the plates of the 6L6s are the correct voltage too. So the speaker transformer is good too. The 6L6s test good.
:::: I'll now check the voltages on the 6R7G (none of the resistors are open there either).
:::: As I already said, between grid and cathode on the 6J5 driver tube I have .5 volts (now it's .48 volts) , not 3. On the 6R7 I have 2.0 volts between grid and cathode (negative meter lead is on the grid). Where could the missing voltage be on the 6J5? All resistors are good. I removed them from the circuit and they are good. I used a 390K resistor to replace the 350 which had drifted to about 600K. I don't have a 350K. I have a 330 K. An open resistor has to be somewhere. But I don't see any. Neither of the chokes is open either. Where should I look next? The 6J5 tests good.
::::
::::Thanks,
::::
::::Dave...
:::::Dave
:::::
::::: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
:::::
::::: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
:::::
:::::Norm
:::::
::::::
:::::
:::::
:::::
::::::Norm,
:::::: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
::::::
::::::Thanks,
::::::
::::::Dave...
::::::
:::::::Norm,
::::::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
:::::::
::::::::Dave
::::::::
:::::::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
::::::::
:::::::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
::::::::
::::::::Norm
::::::::
:::::::::Norm,
:::::::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
:::::::::
:::::::::Thanks,
:::::::::
:::::::::Dave...
::::::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
::::::::::
:::::::::::Norm,
::::::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:::::::::::
:::::::::::Thanks,
:::::::::::
::::::::::::Dave
::::::::::::
:::::::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::::::::::::
::::::::::::Norm
::::::::::::
:::::::::::::Norm,
::::::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::::::::::::
:::::::::::::Thanks,
:::::::::::::
:::::::::::::Dave...
::::::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::::::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
::::::::::::::
::::::::::::::Thanks,
::::::::::::::
::::::::::::::
:::::::::::::::Dave
:::::::::::::::
::::::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
::::::::::::::::Norm,
:::::::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::::::::::::
::::::::::::::::Thanks,
::::::::::::::::
::::::::::::::::Dave...
:::::::::::::::::Hi Dave
:::::::::::::::::
::::::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::::::::::::
::::::::::::::::: See if you can find any transformer with two secondary windings.
:::::::::::::::::
:::::::::::::::::Norm
:::::::::::::::::
::::::::::::::::::Hi Norm,
:::::::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::::::::::::
::::::::::::::::::Thanks very much,
::::::::::::::::::
::::::::::::::::::Dave...
:::::::::::::::::::Hi Dave
:::::::::::::::::::
::::::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::::::::::::
::::::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::::::::::::
:::::::::::::::::::Norm
:::::::::::::::::::
::::::::::::::::::::Hello All,
:::::::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::::::::::::
::::::::::::::::::::
::::::::::::::::::::Thanks,
::::::::::::::::::::
::::::::::::::::::::Dave...
:
:Have sent PHILCO service bulletin 273 for the dial
:and 286A for the chassis code 125
:Dave
:
: Now that I am using the same print it might help.. Has cap #79 been replaced and does it have leakage? What voltage do you have between #110 & #111, bottom of schematic. This is where negative grid voltage is generated. Your tube should have this same voltage (pin #5) but a meter may load it down.
:
: Exact resistor value wouldn't matter. Being open or very high would be a problem. 390K is ok.
:
:Norm
:
::The speaker is fine. I even tried another speaker and it does the same thing. The field coil is powered up and the plates of the 6L6s are the correct voltage too. So the speaker transformer is good too. The 6L6s test good.
:: I'll now check the voltages on the 6R7G (none of the resistors are open there either).
:: As I already said, between grid and cathode on the 6J5 driver tube I have .5 volts (now it's .48 volts) , not 3. On the 6R7 I have 2.0 volts between grid and cathode (negative meter lead is on the grid). Where could the missing voltage be on the 6J5? All resistors are good. I removed them from the circuit and they are good. I used a 390K resistor to replace the 350 which had drifted to about 600K. I don't have a 350K. I have a 330 K. An open resistor has to be somewhere. But I don't see any. Neither of the chokes is open either. Where should I look next? The 6J5 tests good.
::
::Thanks,
::
::Dave...
:::Dave
:::
::: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
:::
::: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
:::
:::Norm
:::
::::
:::
:::
:::
::::Norm,
:::: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
::::
::::Thanks,
::::
::::Dave...
::::
:::::Norm,
::::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
:::::
::::::Dave
::::::
:::::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
::::::
:::::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
::::::
::::::Norm
::::::
:::::::Norm,
:::::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
:::::::
:::::::Thanks,
:::::::
:::::::Dave...
::::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
::::::::
:::::::::Norm,
::::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:::::::::
:::::::::Thanks,
:::::::::
::::::::::Dave
::::::::::
:::::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::::::::::
::::::::::Norm
::::::::::
:::::::::::Norm,
::::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::::::::::
:::::::::::Thanks,
:::::::::::
:::::::::::Dave...
::::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
::::::::::::
::::::::::::Thanks,
::::::::::::
::::::::::::
:::::::::::::Dave
:::::::::::::
::::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::::::::::
:::::::::::::Norm
:::::::::::::
::::::::::::::Norm,
:::::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::::::::::
::::::::::::::Thanks,
::::::::::::::
::::::::::::::Dave...
:::::::::::::::Hi Dave
:::::::::::::::
::::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::::::::::
::::::::::::::: See if you can find any transformer with two secondary windings.
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
::::::::::::::::Hi Norm,
:::::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::::::::::
::::::::::::::::Thanks very much,
::::::::::::::::
::::::::::::::::Dave...
:::::::::::::::::Hi Dave
:::::::::::::::::
::::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::::::::::
::::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::::::::::
:::::::::::::::::Norm
:::::::::::::::::
::::::::::::::::::Hello All,
:::::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::::::::::
::::::::::::::::::
::::::::::::::::::Thanks,
::::::::::::::::::
::::::::::::::::::Dave...
Have sent PHILCO service bulletin 273 for the dial
and 286A for the chassis code 125
Thanks Again,
Dave...
::Norm,
:: It still sounds as if the 6L6 are being overloaded by this input transformer. Whether the tone control worked or not, there should be a lot more in the way of low frequencies here. It does still distort but its an overload type distortion and not the clipping sounds as I was getting before.
:: There's plenty more volume too. But it still doesn't sound right.
::
:::Dave
:::
::: Now that I am using the same print it might help.. Has cap #79 been replaced and does it have leakage? What voltage do you have between #110 & #111, bottom of schematic. This is where negative grid voltage is generated. Your tube should have this same voltage (pin #5) but a meter may load it down.
:::
::: Exact resistor value wouldn't matter. Being open or very high would be a problem. 390K is ok.
:::
:::Norm
:::
::::The speaker is fine. I even tried another speaker and it does the same thing. The field coil is powered up and the plates of the 6L6s are the correct voltage too. So the speaker transformer is good too. The 6L6s test good.
:::: I'll now check the voltages on the 6R7G (none of the resistors are open there either).
:::: As I already said, between grid and cathode on the 6J5 driver tube I have .5 volts (now it's .48 volts) , not 3. On the 6R7 I have 2.0 volts between grid and cathode (negative meter lead is on the grid). Where could the missing voltage be on the 6J5? All resistors are good. I removed them from the circuit and they are good. I used a 390K resistor to replace the 350 which had drifted to about 600K. I don't have a 350K. I have a 330 K. An open resistor has to be somewhere. But I don't see any. Neither of the chokes is open either. Where should I look next? The 6J5 tests good.
::::
::::Thanks,
::::
::::Dave...
:::::Dave
:::::
::::: Check between grid & cathode on your 6J5G driver & 6R7G 1st audio. Grid must be slightly negative. Minus 3 volts would be reasonable. If it's positive or very negative audio will distort. Plates on both tubes need to be positive. (pin #3)
:::::
::::: You mention sound is ok very low. Check the speaker. Be sure your cone moves freely without rubbing.
:::::
:::::Norm
:::::
::::::
:::::
:::::
:::::
::::::Norm,
:::::: When I turn it down to a volume where it's crystal clear, it's almost at a whisper, its so quiet. When I turn it up it gets louder but it's 100 % distorted. You can hear the clear quiet clear audio but when it gets loud, those loud bits are distorted. It's still very quiet when loud. I don't know how else to describe it, unless I make a recording of it for you.
::::::
::::::Thanks,
::::::
::::::Dave...
::::::
:::::::Norm,
::::::: It's not open and the 25K ohm resistor that it's in series with isn't open either. I replaced the resistor and it still distorts. This is getting very frustrating. When it isn't distorting, its barely audable. I have to have the volume all the way up to hear anything. There are no low frequencies.
:::::::
::::::::Dave
::::::::
:::::::: The resistor from grid #1 to negative may be open? This would allow your grid to float & distort. It's 114 in the schematic I used. You may be looking at a slight different one?
::::::::
:::::::: http://www.nostalgiaair.org/PagesByModel/234/M0013234.pdf
::::::::
::::::::Norm
::::::::
:::::::::Norm,
:::::::::Resistor 114 is a 20 ohm resistor, according to Riders pages 9-11, 9-12. I hope we're both looking at 38-116 Code 125. I think you mean resistor 94. I'll check it. All paper + filter capacitors except capacitor #7 have been replaced. I'll tackle it's replacement later. I will have to take out the sub-chassis to get to it.
:::::::::
:::::::::Thanks,
:::::::::
:::::::::Dave...
::::::::::Also be sure resistor 114, 330K, hasn't gone up in value or opened..
::::::::::
:::::::::::Norm,
::::::::::: On the 6L6 tubes I get 25.9 volts, as you said it should be. On the driver tube, 6J5 when I measure from the grid to the cathode, when I first turn on the set, it shoots up to 400+ volts as its "Warming up", then it comes down to .5 volts (as soon as I hear sound) and stays there. Is this what should be happening or should I look for a problem in the area of the driver?
:::::::::::
:::::::::::Thanks,
:::::::::::
::::::::::::Dave
::::::::::::
:::::::::::: Check bias on your audio tubes. 6L6 pin #5 should be around 20 volts negative in relation to pin #8. Other audio tubes should have grid #1 a couple volts negative in relation to cathode. If positive you will have distortion. You may not have overloading but distortion from non linear operation?
::::::::::::
::::::::::::Norm
::::::::::::
:::::::::::::Norm,
::::::::::::: It helped a little, but it's still overloading. The old transformer seemed to be a step-down transformer. The primary was 400 ohms and each of the secondaries was about 150 ohms. But this one has a 600 ohm primary and two 2.4K secondaries (a step-up transformer). Maybe I need to hook it up in reverse some how, using the primary as the secondary and a secondary as the primary. I need to do something because it doesn't sound right. What do you suggest I do?
:::::::::::::
:::::::::::::Thanks,
:::::::::::::
:::::::::::::Dave...
::::::::::::::I hooked it up and have no low frequencies. I sounds as if it's distorting. If I turn the volume down until it sounds ok, its not loud enough for comfortable listening. The DC resistance of each of the secondaries is about 2K ohms. I am using only one of the primary windings. Would it help if I used the entire primary? Good Idea, I'll try that. It will take a couple of minutes and I will let you know.
:::::::::::::: Maybe there is a speacial way to connect the ends of the secondaries.
::::::::::::::
::::::::::::::Thanks,
::::::::::::::
::::::::::::::
:::::::::::::::Dave
:::::::::::::::
::::::::::::::: Each winding can have the same number of turns but different resistance. The inside winding will be lower resistance as it takes less wire to make a turn.
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
::::::::::::::::Norm,
:::::::::::::::: The Hammond does have two separate secondar windings. It has a center tapped primary. So it should work perfectly.
:::::::::::::::: The DC resistance is higher in one of the windings though. I forgot which one it was. I'll let you know how it works because I should be receiving it today.
::::::::::::::::
::::::::::::::::Thanks,
::::::::::::::::
::::::::::::::::Dave...
:::::::::::::::::Hi Dave
:::::::::::::::::
::::::::::::::::: I see what you mean. Don't think the Hammond transformer has two secondary windings. You can use a transformer without center tap but need a circuit change. The resistors in series with each winding would have to be eliminated. This would remove a negative feedback circuit. You can add negative feedback in a different way.
:::::::::::::::::
::::::::::::::::: See if you can find any transformer with two secondary windings.
:::::::::::::::::
:::::::::::::::::Norm
:::::::::::::::::
::::::::::::::::::Hi Norm,
:::::::::::::::::: It is because the original transformer is rated in resistance instead of impedance that asked here in the Forum about it. I knew that the one of the 124 series of transformers had to work. The original transformer secondary isn't center tapped. There are two separate windings. If the Hammond 124E has separate windings in the secondary, I'll use that.
::::::::::::::::::
::::::::::::::::::Thanks very much,
::::::::::::::::::
::::::::::::::::::Dave...
:::::::::::::::::::Hi Dave
:::::::::::::::::::
::::::::::::::::::: A replacement wouldn't have those ratings. Those numbers are in DC resistance for testing with an ohm meter. In a catalog a transformer is rated by impedance, which will be a much higher number.
:::::::::::::::::::
::::::::::::::::::: Your original transforners seems to have a 1:1 ratio with the secondary center tapped. Look for a Hammond transformer rated something like 10,000 ohm impedance primary & secondary. You could use a higher ratio but that would give more gain than the original. P-T124E AES transformer number, made by Hammond, has a center tapped primary & secondary so you can select gain.
:::::::::::::::::::
:::::::::::::::::::Norm
:::::::::::::::::::
::::::::::::::::::::Hello All,
:::::::::::::::::::: Which transformer is a good substitute for the driver transformer in this set? This one has an open primary. It's supposed to be 400 ohms, but this one is wide open. The two secondary windings are good. One is 150 ohms and one is 175 ohms, just as they are suppoed to be. I have looked through the Hammond transformers but cannot find one with a 400 ohm primary.
:::::::::::::::::::: I have looked through some of the Hammond driver transformers but don't see one that has a 400 ohm primary.
::::::::::::::::::::
::::::::::::::::::::
::::::::::::::::::::Thanks,
::::::::::::::::::::
::::::::::::::::::::Dave...
:
:Have sent PHILCO service bulletin 273 for the dial
:and 286A for the chassis code 125