Some have had the same results. Since they are solid state one slight problem and it's burned out. Inside the vibrator are semiconductors. They can't withstand a high voltage spike. If you have a good mechanical vibrator best to use it, at least until everything is working correctly.
You have the best way to check the vibrator, right in a radio.
Norm
:Is there any way to check if a Solid State Vibrator is any good? Reason for my question is I purchased one for a 1948 chrysler pos ground pluged it in got a little bit of static from radio then about 30 seconds nothing checked for high voltage at rectifier and had a whopping 3 volts, put the old vibrator back in and the radio started playing with about 100 volts at the rectifier, ( the owned told me the radio just buzzed so I assumed it was the vibrator)I did replace the buffer cap as well not to mention all the paper caps what is a SS vibrator comprised of? are they worth the cost ( I am begining to think not) any help is apprecated.
:Thanks
:E.
Putting a vibrator designed for a negative ground radio in a pos. ground radio will possibly destroy the vibrator. Solid state vibrators are in some ways better than mechanical vibrators, because they don't wear out as much, though semiconductors definitely fail. They don't last forever, and I'm beginning to believe that they sometimes have a shorter life span than tubes. They are delicate when it comes to voltage spikes. Mechanical vibrators can deliver more current, too, though more current can also pit the points. They are also more likely to create radio interference, and do create a small amount of mechanical noise. Solid state vibrators can be run at higher frequencies, which can make the transformer operate more efficiently (to a degree).
If the radio hums, be sure to replace its electrolytics, like any other radio. Replace electrolytics. Replace paper capacitors. Check resistors and replace those which are over 20% out of tolerance, or those which don't make the radio work properly, even if they are within the 20% limit. The buffer capacitor must be able to withstand several thousand volts. It's best to go with a ceramic unit that can withstand at least 3 KV. Even though you only see about 200 or 300 volts in the B supply, when the points open, the transformer operates just like an ignition coil. A sudden collapse of magnetism creates a huge voltage in the secondary. The resistors across the vibrator points smooth this out to a degree. Resistance across points is definitely something you don't want in an ignition system if you want a good spark, which is why they are not used to protect ignition points. A capacitor is used on ignition points. Its capacitance must match many things in the circuit to create the ideal voltage collapse, and to prevent pitting of the points (something many people don't know when they complain about pitting points...you shouldn't just use whatever the auto store gives you). You never want to use capacitors in the primary of a radio vibrator circuit, because they will aid in the transformer's ability to produce huge voltages. ....Not that I expect you to modify the vibrator circuit, but these are key things to know for your understanding of why certain things happen in the vibrator circuit, what's done to prevent them, and what you can do to repair trouble involving these things. Also, the prevention of high voltage spikes can aid in protecting a solid state vibrator. Check all components in the vibrator circuit, and replace faulty ones. Resistors should be within 10%, since they handle lower voltages. The buffer capacitor cannot be properly checked unless you have a checker capable of putting out over 1000 volts.
T.
Do you have the original vibrator? If so, in most cases, it can be taken apart and adjusted. You also might be able to operate a vibrator off the 120 volt AC line with 40-60 watt lamp in series. The high voltage will clean points while the lamp prevents too much current.
Even if you find a new vibrator it may not operate. Over time rubber inside, used to reduce noise, cause points to oxidize. These usually can be cleaned with the high voltage and lamp setup.
Norm
::Since semiconductors are polarity sensitive, you must be sure to buy the correct vibrator for the radio in which you are using it. Radios that have a rectifier tube are not usually polarity sensitive, and with a mechanical vibrator, can be wired up any way you please. Radios without a rectifier, and with a synchronous vibrator are polarity sensitive as is. All radios, when converted to a solid state vibrator, must be connected according to what the vibrator is made for. When purchasing a solid state vibrator for a radio that takes a synchronous vibrator, first establish the original polarity requirement for the radio, and then buy a vibrator to suit that polarity.
::
::Putting a vibrator designed for a negative ground radio in a pos. ground radio will possibly destroy the vibrator. Solid state vibrators are in some ways better than mechanical vibrators, because they don't wear out as much, though semiconductors definitely fail. They don't last forever, and I'm beginning to believe that they sometimes have a shorter life span than tubes. They are delicate when it comes to voltage spikes. Mechanical vibrators can deliver more current, too, though more current can also pit the points. They are also more likely to create radio interference, and do create a small amount of mechanical noise. Solid state vibrators can be run at higher frequencies, which can make the transformer operate more efficiently (to a degree).
::
::If the radio hums, be sure to replace its electrolytics, like any other radio. Replace electrolytics. Replace paper capacitors. Check resistors and replace those which are over 20% out of tolerance, or those which don't make the radio work properly, even if they are within the 20% limit. The buffer capacitor must be able to withstand several thousand volts. It's best to go with a ceramic unit that can withstand at least 3 KV. Even though you only see about 200 or 300 volts in the B supply, when the points open, the transformer operates just like an ignition coil. A sudden collapse of magnetism creates a huge voltage in the secondary. The resistors across the vibrator points smooth this out to a degree. Resistance across points is definitely something you don't want in an ignition system if you want a good spark, which is why they are not used to protect ignition points. A capacitor is used on ignition points. Its capacitance must match many things in the circuit to create the ideal voltage collapse, and to prevent pitting of the points (something many people don't know when they complain about pitting points...you shouldn't just use whatever the auto store gives you). You never want to use capacitors in the primary of a radio vibrator circuit, because they will aid in the transformer's ability to produce huge voltages. ....Not that I expect you to modify the vibrator circuit, but these are key things to know for your understanding of why certain things happen in the vibrator circuit, what's done to prevent them, and what you can do to repair trouble involving these things. Also, the prevention of high voltage spikes can aid in protecting a solid state vibrator. Check all components in the vibrator circuit, and replace faulty ones. Resistors should be within 10%, since they handle lower voltages. The buffer capacitor cannot be properly checked unless you have a checker capable of putting out over 1000 volts.
::
::T.
:Hi Thomas, thanks for the notes. I am working on my first antique auto radio, a Chev. model 986388 and I am having a tough time finding a known good traditional vibrator for this radio. I bought a solid state unit from Radio Daze and I don't seem to get the correct A/C out of the transformer. The radio seems to work fairly well, a little lacking in sensitivity due to the low B+, with a slight "whine" which I assume is from the solid state unit, or field from the step up transf. Where can I find a known good NOS vibrator for this radio? I want to make sure it is working right before I send back the solid state unit. All caps have been changed, resistors seem within tolerance, no open windings in coils or transformers. I've had a tough time finding parts for this radio. I am powering it with an old Mallory 6RS10 supply designed for exactly such service. I would appreciate any help you can afford. Best Regards, Ron.
:Ron
:
: Do you have the original vibrator? If so, in most cases, it can be taken apart and adjusted. You also might be able to operate a vibrator off the 120 volt AC line with 40-60 watt lamp in series. The high voltage will clean points while the lamp prevents too much current.
:
: Even if you find a new vibrator it may not operate. Over time rubber inside, used to reduce noise, cause points to oxidize. These usually can be cleaned with the high voltage and lamp setup.
:
:Norm
:
:
:
:::Since semiconductors are polarity sensitive, you must be sure to buy the correct vibrator for the radio in which you are using it. Radios that have a rectifier tube are not usually polarity sensitive, and with a mechanical vibrator, can be wired up any way you please. Radios without a rectifier, and with a synchronous vibrator are polarity sensitive as is. All radios, when converted to a solid state vibrator, must be connected according to what the vibrator is made for. When purchasing a solid state vibrator for a radio that takes a synchronous vibrator, first establish the original polarity requirement for the radio, and then buy a vibrator to suit that polarity.
:::
:::Putting a vibrator designed for a negative ground radio in a pos. ground radio will possibly destroy the vibrator. Solid state vibrators are in some ways better than mechanical vibrators, because they don't wear out as much, though semiconductors definitely fail. They don't last forever, and I'm beginning to believe that they sometimes have a shorter life span than tubes. They are delicate when it comes to voltage spikes. Mechanical vibrators can deliver more current, too, though more current can also pit the points. They are also more likely to create radio interference, and do create a small amount of mechanical noise. Solid state vibrators can be run at higher frequencies, which can make the transformer operate more efficiently (to a degree).
:::
:::If the radio hums, be sure to replace its electrolytics, like any other radio. Replace electrolytics. Replace paper capacitors. Check resistors and replace those which are over 20% out of tolerance, or those which don't make the radio work properly, even if they are within the 20% limit. The buffer capacitor must be able to withstand several thousand volts. It's best to go with a ceramic unit that can withstand at least 3 KV. Even though you only see about 200 or 300 volts in the B supply, when the points open, the transformer operates just like an ignition coil. A sudden collapse of magnetism creates a huge voltage in the secondary. The resistors across the vibrator points smooth this out to a degree. Resistance across points is definitely something you don't want in an ignition system if you want a good spark, which is why they are not used to protect ignition points. A capacitor is used on ignition points. Its capacitance must match many things in the circuit to create the ideal voltage collapse, and to prevent pitting of the points (something many people don't know when they complain about pitting points...you shouldn't just use whatever the auto store gives you). You never want to use capacitors in the primary of a radio vibrator circuit, because they will aid in the transformer's ability to produce huge voltages. ....Not that I expect you to modify the vibrator circuit, but these are key things to know for your understanding of why certain things happen in the vibrator circuit, what's done to prevent them, and what you can do to repair trouble involving these things. Also, the prevention of high voltage spikes can aid in protecting a solid state vibrator. Check all components in the vibrator circuit, and replace faulty ones. Resistors should be within 10%, since they handle lower voltages. The buffer capacitor cannot be properly checked unless you have a checker capable of putting out over 1000 volts.
:::
:::T.
::Hi Thomas, thanks for the notes. I am working on my first antique auto radio, a Chev. model 986388 and I am having a tough time finding a known good traditional vibrator for this radio. I bought a solid state unit from Radio Daze and I don't seem to get the correct A/C out of the transformer. The radio seems to work fairly well, a little lacking in sensitivity due to the low B+, with a slight "whine" which I assume is from the solid state unit, or field from the step up transf. Where can I find a known good NOS vibrator for this radio? I want to make sure it is working right before I send back the solid state unit. All caps have been changed, resistors seem within tolerance, no open windings in coils or transformers. I've had a tough time finding parts for this radio. I am powering it with an old Mallory 6RS10 supply designed for exactly such service. I would appreciate any help you can afford. Best Regards, Ron.
This is what I was experiencing with my solid state unit and although the radio works well for strong local signals, it is not sensitive enough to pick up medium or weaker signals. What should I check next? or do you think my trans. is the culprit? What could happen to that that would reduce the secondary voltage by 100V., but still work well enough to run the radio, and does not show up in any sort of continuity checks?
Anyone have any ideas here? This radio is a gift for my father for Dad's day and I was hoping to get it running right this week.
:Ron
:
: Do you have the original vibrator? If so, in most cases, it can be taken apart and adjusted. You also might be able to operate a vibrator off the 120 volt AC line with 40-60 watt lamp in series. The high voltage will clean points while the lamp prevents too much current.
:
: Even if you find a new vibrator it may not operate. Over time rubber inside, used to reduce noise, cause points to oxidize. These usually can be cleaned with the high voltage and lamp setup.
:
:Norm
:
:
:
:::Since semiconductors are polarity sensitive, you must be sure to buy the correct vibrator for the radio in which you are using it. Radios that have a rectifier tube are not usually polarity sensitive, and with a mechanical vibrator, can be wired up any way you please. Radios without a rectifier, and with a synchronous vibrator are polarity sensitive as is. All radios, when converted to a solid state vibrator, must be connected according to what the vibrator is made for. When purchasing a solid state vibrator for a radio that takes a synchronous vibrator, first establish the original polarity requirement for the radio, and then buy a vibrator to suit that polarity.
:::
:::Putting a vibrator designed for a negative ground radio in a pos. ground radio will possibly destroy the vibrator. Solid state vibrators are in some ways better than mechanical vibrators, because they don't wear out as much, though semiconductors definitely fail. They don't last forever, and I'm beginning to believe that they sometimes have a shorter life span than tubes. They are delicate when it comes to voltage spikes. Mechanical vibrators can deliver more current, too, though more current can also pit the points. They are also more likely to create radio interference, and do create a small amount of mechanical noise. Solid state vibrators can be run at higher frequencies, which can make the transformer operate more efficiently (to a degree).
:::
:::If the radio hums, be sure to replace its electrolytics, like any other radio. Replace electrolytics. Replace paper capacitors. Check resistors and replace those which are over 20% out of tolerance, or those which don't make the radio work properly, even if they are within the 20% limit. The buffer capacitor must be able to withstand several thousand volts. It's best to go with a ceramic unit that can withstand at least 3 KV. Even though you only see about 200 or 300 volts in the B supply, when the points open, the transformer operates just like an ignition coil. A sudden collapse of magnetism creates a huge voltage in the secondary. The resistors across the vibrator points smooth this out to a degree. Resistance across points is definitely something you don't want in an ignition system if you want a good spark, which is why they are not used to protect ignition points. A capacitor is used on ignition points. Its capacitance must match many things in the circuit to create the ideal voltage collapse, and to prevent pitting of the points (something many people don't know when they complain about pitting points...you shouldn't just use whatever the auto store gives you). You never want to use capacitors in the primary of a radio vibrator circuit, because they will aid in the transformer's ability to produce huge voltages. ....Not that I expect you to modify the vibrator circuit, but these are key things to know for your understanding of why certain things happen in the vibrator circuit, what's done to prevent them, and what you can do to repair trouble involving these things. Also, the prevention of high voltage spikes can aid in protecting a solid state vibrator. Check all components in the vibrator circuit, and replace faulty ones. Resistors should be within 10%, since they handle lower voltages. The buffer capacitor cannot be properly checked unless you have a checker capable of putting out over 1000 volts.
:::
:::T.
::Hi Thomas, thanks for the notes. I am working on my first antique auto radio, a Chev. model 986388 and I am having a tough time finding a known good traditional vibrator for this radio. I bought a solid state unit from Radio Daze and I don't seem to get the correct A/C out of the transformer. The radio seems to work fairly well, a little lacking in sensitivity due to the low B+, with a slight "whine" which I assume is from the solid state unit, or field from the step up transf. Where can I find a known good NOS vibrator for this radio? I want to make sure it is working right before I send back the solid state unit. All caps have been changed, resistors seem within tolerance, no open windings in coils or transformers. I've had a tough time finding parts for this radio. I am powering it with an old Mallory 6RS10 supply designed for exactly such service. I would appreciate any help you can afford. Best Regards, Ron.
Here are several things:
What voltage are you using for testing? If a 6 volt battery voltage will be low at the radio.
Did you replace buffer cap with the same value?
Vibrator points may not be perfect? Not having perfect contact causes voltage out of the transformer to be low. Not a transformer problem.
Could replace the 0Z4 with silicon diodes? They have lower voltage drop. An 0Z4 needs a specific voltage to operate. You are getting down near the firing point. Any lower and it won't operate.
Norm
:Norm,
:OK, I took your suggestion and "cleaned" an original type vibrator with the A/C trick. It worked! Now, I have gone over the voltages and measured all of the resistors, checked the continuity of coils and transformers, etc. Everything is within tolerances except for the B+ voltage. Upon checking the voltage straight out of the step up transformer, it shows only 150V. A/C. at each plate of the rectifier. (Thus the lower B+ DC readings later on in the circuit.) All tubes check good and the 0Z4 is "NOS" and checks perfect on my Hickok 800 tester.
:
:This is what I was experiencing with my solid state unit and although the radio works well for strong local signals, it is not sensitive enough to pick up medium or weaker signals. What should I check next? or do you think my trans. is the culprit? What could happen to that that would reduce the secondary voltage by 100V., but still work well enough to run the radio, and does not show up in any sort of continuity checks?
:
:Anyone have any ideas here? This radio is a gift for my father for Dad's day and I was hoping to get it running right this week.
:
::Ron
::
:: Do you have the original vibrator? If so, in most cases, it can be taken apart and adjusted. You also might be able to operate a vibrator off the 120 volt AC line with 40-60 watt lamp in series. The high voltage will clean points while the lamp prevents too much current.
::
:: Even if you find a new vibrator it may not operate. Over time rubber inside, used to reduce noise, cause points to oxidize. These usually can be cleaned with the high voltage and lamp setup.
::
::Norm
::
::
::
::::Since semiconductors are polarity sensitive, you must be sure to buy the correct vibrator for the radio in which you are using it. Radios that have a rectifier tube are not usually polarity sensitive, and with a mechanical vibrator, can be wired up any way you please. Radios without a rectifier, and with a synchronous vibrator are polarity sensitive as is. All radios, when converted to a solid state vibrator, must be connected according to what the vibrator is made for. When purchasing a solid state vibrator for a radio that takes a synchronous vibrator, first establish the original polarity requirement for the radio, and then buy a vibrator to suit that polarity.
::::
::::Putting a vibrator designed for a negative ground radio in a pos. ground radio will possibly destroy the vibrator. Solid state vibrators are in some ways better than mechanical vibrators, because they don't wear out as much, though semiconductors definitely fail. They don't last forever, and I'm beginning to believe that they sometimes have a shorter life span than tubes. They are delicate when it comes to voltage spikes. Mechanical vibrators can deliver more current, too, though more current can also pit the points. They are also more likely to create radio interference, and do create a small amount of mechanical noise. Solid state vibrators can be run at higher frequencies, which can make the transformer operate more efficiently (to a degree).
::::
::::If the radio hums, be sure to replace its electrolytics, like any other radio. Replace electrolytics. Replace paper capacitors. Check resistors and replace those which are over 20% out of tolerance, or those which don't make the radio work properly, even if they are within the 20% limit. The buffer capacitor must be able to withstand several thousand volts. It's best to go with a ceramic unit that can withstand at least 3 KV. Even though you only see about 200 or 300 volts in the B supply, when the points open, the transformer operates just like an ignition coil. A sudden collapse of magnetism creates a huge voltage in the secondary. The resistors across the vibrator points smooth this out to a degree. Resistance across points is definitely something you don't want in an ignition system if you want a good spark, which is why they are not used to protect ignition points. A capacitor is used on ignition points. Its capacitance must match many things in the circuit to create the ideal voltage collapse, and to prevent pitting of the points (something many people don't know when they complain about pitting points...you shouldn't just use whatever the auto store gives you). You never want to use capacitors in the primary of a radio vibrator circuit, because they will aid in the transformer's ability to produce huge voltages. ....Not that I expect you to modify the vibrator circuit, but these are key things to know for your understanding of why certain things happen in the vibrator circuit, what's done to prevent them, and what you can do to repair trouble involving these things. Also, the prevention of high voltage spikes can aid in protecting a solid state vibrator. Check all components in the vibrator circuit, and replace faulty ones. Resistors should be within 10%, since they handle lower voltages. The buffer capacitor cannot be properly checked unless you have a checker capable of putting out over 1000 volts.
::::
::::T.
:::Hi Thomas, thanks for the notes. I am working on my first antique auto radio, a Chev. model 986388 and I am having a tough time finding a known good traditional vibrator for this radio. I bought a solid state unit from Radio Daze and I don't seem to get the correct A/C out of the transformer. The radio seems to work fairly well, a little lacking in sensitivity due to the low B+, with a slight "whine" which I assume is from the solid state unit, or field from the step up transf. Where can I find a known good NOS vibrator for this radio? I want to make sure it is working right before I send back the solid state unit. All caps have been changed, resistors seem within tolerance, no open windings in coils or transformers. I've had a tough time finding parts for this radio. I am powering it with an old Mallory 6RS10 supply designed for exactly such service. I would appreciate any help you can afford. Best Regards, Ron.
:Ronald
:
: Here are several things:
:
: What voltage are you using for testing? If a 6 volt battery voltage will be low at the radio.
:
: Did you replace buffer cap with the same value?
:
: Vibrator points may not be perfect? Not having perfect contact causes voltage out of the transformer to be low. Not a transformer problem.
:
: Could replace the 0Z4 with silicon diodes? They have lower voltage drop. An 0Z4 needs a specific voltage to operate. You are getting down near the firing point. Any lower and it won't operate.
:
:Norm
:
:
:
:
:
::Norm,
::OK, I took your suggestion and "cleaned" an original type vibrator with the A/C trick. It worked! Now, I have gone over the voltages and measured all of the resistors, checked the continuity of coils and transformers, etc. Everything is within tolerances except for the B+ voltage. Upon checking the voltage straight out of the step up transformer, it shows only 150V. A/C. at each plate of the rectifier. (Thus the lower B+ DC readings later on in the circuit.) All tubes check good and the 0Z4 is "NOS" and checks perfect on my Hickok 800 tester.
::
::This is what I was experiencing with my solid state unit and although the radio works well for strong local signals, it is not sensitive enough to pick up medium or weaker signals. What should I check next? or do you think my trans. is the culprit? What could happen to that that would reduce the secondary voltage by 100V., but still work well enough to run the radio, and does not show up in any sort of continuity checks?
::
::Anyone have any ideas here? This radio is a gift for my father for Dad's day and I was hoping to get it running right this week.
::
:::Ron
:::
::: Do you have the original vibrator? If so, in most cases, it can be taken apart and adjusted. You also might be able to operate a vibrator off the 120 volt AC line with 40-60 watt lamp in series. The high voltage will clean points while the lamp prevents too much current.
:::
::: Even if you find a new vibrator it may not operate. Over time rubber inside, used to reduce noise, cause points to oxidize. These usually can be cleaned with the high voltage and lamp setup.
:::
:::Norm
:::
:::
:::
:::::Since semiconductors are polarity sensitive, you must be sure to buy the correct vibrator for the radio in which you are using it. Radios that have a rectifier tube are not usually polarity sensitive, and with a mechanical vibrator, can be wired up any way you please. Radios without a rectifier, and with a synchronous vibrator are polarity sensitive as is. All radios, when converted to a solid state vibrator, must be connected according to what the vibrator is made for. When purchasing a solid state vibrator for a radio that takes a synchronous vibrator, first establish the original polarity requirement for the radio, and then buy a vibrator to suit that polarity.
:::::
:::::Putting a vibrator designed for a negative ground radio in a pos. ground radio will possibly destroy the vibrator. Solid state vibrators are in some ways better than mechanical vibrators, because they don't wear out as much, though semiconductors definitely fail. They don't last forever, and I'm beginning to believe that they sometimes have a shorter life span than tubes. They are delicate when it comes to voltage spikes. Mechanical vibrators can deliver more current, too, though more current can also pit the points. They are also more likely to create radio interference, and do create a small amount of mechanical noise. Solid state vibrators can be run at higher frequencies, which can make the transformer operate more efficiently (to a degree).
:::::
:::::If the radio hums, be sure to replace its electrolytics, like any other radio. Replace electrolytics. Replace paper capacitors. Check resistors and replace those which are over 20% out of tolerance, or those which don't make the radio work properly, even if they are within the 20% limit. The buffer capacitor must be able to withstand several thousand volts. It's best to go with a ceramic unit that can withstand at least 3 KV. Even though you only see about 200 or 300 volts in the B supply, when the points open, the transformer operates just like an ignition coil. A sudden collapse of magnetism creates a huge voltage in the secondary. The resistors across the vibrator points smooth this out to a degree. Resistance across points is definitely something you don't want in an ignition system if you want a good spark, which is why they are not used to protect ignition points. A capacitor is used on ignition points. Its capacitance must match many things in the circuit to create the ideal voltage collapse, and to prevent pitting of the points (something many people don't know when they complain about pitting points...you shouldn't just use whatever the auto store gives you). You never want to use capacitors in the primary of a radio vibrator circuit, because they will aid in the transformer's ability to produce huge voltages. ....Not that I expect you to modify the vibrator circuit, but these are key things to know for your understanding of why certain things happen in the vibrator circuit, what's done to prevent them, and what you can do to repair trouble involving these things. Also, the prevention of high voltage spikes can aid in protecting a solid state vibrator. Check all components in the vibrator circuit, and replace faulty ones. Resistors should be within 10%, since they handle lower voltages. The buffer capacitor cannot be properly checked unless you have a checker capable of putting out over 1000 volts.
:::::
:::::T.
::::Hi Thomas, thanks for the notes. I am working on my first antique auto radio, a Chev. model 986388 and I am having a tough time finding a known good traditional vibrator for this radio. I bought a solid state unit from Radio Daze and I don't seem to get the correct A/C out of the transformer. The radio seems to work fairly well, a little lacking in sensitivity due to the low B+, with a slight "whine" which I assume is from the solid state unit, or field from the step up transf. Where can I find a known good NOS vibrator for this radio? I want to make sure it is working right before I send back the solid state unit. All caps have been changed, resistors seem within tolerance, no open windings in coils or transformers. I've had a tough time finding parts for this radio. I am powering it with an old Mallory 6RS10 supply designed for exactly such service. I would appreciate any help you can afford. Best Regards, Ron.
I forget some background, reading posts on different forums.
Your transformer isn't the problem. A bad transformer burns up quickly even with a couple turns shorted. Believe you mentioned both plates of the 0Z4 have the same low voltage? Transformer is not open or you wouldn't have any voltage.
Could the radio circuitry be drawing too much current? An output tube with leaky grid 1 coupling capacitor will draw excessive current. Pull the 6V6 or what output tube your radio uses. Voltage will go up. See if it becomes normal? With the 0Z4 removed is voltage normal at plate pins?
Even with the Mallory supply voltage can be low at the radio. These radios draw a lot of current. A few feet of lead wire can drop a volt or so. Do you have reasonable voltage at tube filament pins.
Norm
:Hi Norm,
:Thanks for the continued discussion. FYI- I have used both a "real" vibrator and a solid state replacement with the same B+ readings, i.e. the same A/C at the second stage of the transf. with (2) different 0Z4 diodes, a buffer cap of .006, .004, and .008. There was an .008 in originally, but the diagrams show variations from .006 to .008, depending on the release. Swapping any of these has no effect on the output voltage at the trans. secondary. I even tried removing the load resistor that runs across the vibrator and/or changing it's value with no affect. As I stated earlier, I am using a Mallory 6RS10 bench supply made just for this purpose. What do you think next?
:Thanks for your continued help. Ron.
:
::Ronald
::
:: Here are several things:
::
:: What voltage are you using for testing? If a 6 volt battery voltage will be low at the radio.
::
:: Did you replace buffer cap with the same value?
::
:: Vibrator points may not be perfect? Not having perfect contact causes voltage out of the transformer to be low. Not a transformer problem.
::
:: Could replace the 0Z4 with silicon diodes? They have lower voltage drop. An 0Z4 needs a specific voltage to operate. You are getting down near the firing point. Any lower and it won't operate.
::
::Norm
::
::
::
::
::
:::Norm,
:::OK, I took your suggestion and "cleaned" an original type vibrator with the A/C trick. It worked! Now, I have gone over the voltages and measured all of the resistors, checked the continuity of coils and transformers, etc. Everything is within tolerances except for the B+ voltage. Upon checking the voltage straight out of the step up transformer, it shows only 150V. A/C. at each plate of the rectifier. (Thus the lower B+ DC readings later on in the circuit.) All tubes check good and the 0Z4 is "NOS" and checks perfect on my Hickok 800 tester.
:::
:::This is what I was experiencing with my solid state unit and although the radio works well for strong local signals, it is not sensitive enough to pick up medium or weaker signals. What should I check next? or do you think my trans. is the culprit? What could happen to that that would reduce the secondary voltage by 100V., but still work well enough to run the radio, and does not show up in any sort of continuity checks?
:::
:::Anyone have any ideas here? This radio is a gift for my father for Dad's day and I was hoping to get it running right this week.
:::
::::Ron
::::
:::: Do you have the original vibrator? If so, in most cases, it can be taken apart and adjusted. You also might be able to operate a vibrator off the 120 volt AC line with 40-60 watt lamp in series. The high voltage will clean points while the lamp prevents too much current.
::::
:::: Even if you find a new vibrator it may not operate. Over time rubber inside, used to reduce noise, cause points to oxidize. These usually can be cleaned with the high voltage and lamp setup.
::::
::::Norm
::::
::::
::::
::::::Since semiconductors are polarity sensitive, you must be sure to buy the correct vibrator for the radio in which you are using it. Radios that have a rectifier tube are not usually polarity sensitive, and with a mechanical vibrator, can be wired up any way you please. Radios without a rectifier, and with a synchronous vibrator are polarity sensitive as is. All radios, when converted to a solid state vibrator, must be connected according to what the vibrator is made for. When purchasing a solid state vibrator for a radio that takes a synchronous vibrator, first establish the original polarity requirement for the radio, and then buy a vibrator to suit that polarity.
::::::
::::::Putting a vibrator designed for a negative ground radio in a pos. ground radio will possibly destroy the vibrator. Solid state vibrators are in some ways better than mechanical vibrators, because they don't wear out as much, though semiconductors definitely fail. They don't last forever, and I'm beginning to believe that they sometimes have a shorter life span than tubes. They are delicate when it comes to voltage spikes. Mechanical vibrators can deliver more current, too, though more current can also pit the points. They are also more likely to create radio interference, and do create a small amount of mechanical noise. Solid state vibrators can be run at higher frequencies, which can make the transformer operate more efficiently (to a degree).
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::::::If the radio hums, be sure to replace its electrolytics, like any other radio. Replace electrolytics. Replace paper capacitors. Check resistors and replace those which are over 20% out of tolerance, or those which don't make the radio work properly, even if they are within the 20% limit. The buffer capacitor must be able to withstand several thousand volts. It's best to go with a ceramic unit that can withstand at least 3 KV. Even though you only see about 200 or 300 volts in the B supply, when the points open, the transformer operates just like an ignition coil. A sudden collapse of magnetism creates a huge voltage in the secondary. The resistors across the vibrator points smooth this out to a degree. Resistance across points is definitely something you don't want in an ignition system if you want a good spark, which is why they are not used to protect ignition points. A capacitor is used on ignition points. Its capacitance must match many things in the circuit to create the ideal voltage collapse, and to prevent pitting of the points (something many people don't know when they complain about pitting points...you shouldn't just use whatever the auto store gives you). You never want to use capacitors in the primary of a radio vibrator circuit, because they will aid in the transformer's ability to produce huge voltages. ....Not that I expect you to modify the vibrator circuit, but these are key things to know for your understanding of why certain things happen in the vibrator circuit, what's done to prevent them, and what you can do to repair trouble involving these things. Also, the prevention of high voltage spikes can aid in protecting a solid state vibrator. Check all components in the vibrator circuit, and replace faulty ones. Resistors should be within 10%, since they handle lower voltages. The buffer capacitor cannot be properly checked unless you have a checker capable of putting out over 1000 volts.
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::::::T.
:::::Hi Thomas, thanks for the notes. I am working on my first antique auto radio, a Chev. model 986388 and I am having a tough time finding a known good traditional vibrator for this radio. I bought a solid state unit from Radio Daze and I don't seem to get the correct A/C out of the transformer. The radio seems to work fairly well, a little lacking in sensitivity due to the low B+, with a slight "whine" which I assume is from the solid state unit, or field from the step up transf. Where can I find a known good NOS vibrator for this radio? I want to make sure it is working right before I send back the solid state unit. All caps have been changed, resistors seem within tolerance, no open windings in coils or transformers. I've had a tough time finding parts for this radio. I am powering it with an old Mallory 6RS10 supply designed for exactly such service. I would appreciate any help you can afford. Best Regards, Ron.
You might be able to test it by putting a frequency counter or ociloscope on its output leads, and check to make sure it is putting out a clock signal. If the clock signal is about the same frequency as a normal vibrator and the waveform is good (I beleive they are square wave, but could be sine or triangle) this is a good sign.
The other good sign is that nothing is overheating or shutting down when a high current device is switched through the solid state vibrator. After all, it takes a lot of current at 6V or 12V to turn it into 180-250V B+ Voltage Supply!
Is it safe to run a solid state vibrator off of a 6V bench supply? I'm worried about the ripple, mine has 2V ripple at 6A. Ken
It would be safe. In a car a 6 volt battery might charge up to 8 volts. That's 2 volts.
Norm
:::I've been using a solid state vibrator in place of the synchronous mechanical vibrator in my Airline farm set for a few years now. It runs fairly cool and quiet, with no hash on the radio. I did all of my testing with a mechanical vibrator. Make sure you have the right polarity for the vibrator, and that you replace the buffer caps.
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:Is it safe to run a solid state vibrator off of a 6V bench supply? I'm worried about the ripple, mine has 2V ripple at 6A. Ken