Hello All,
This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.

Thanks,

Dave

Hello Again All,
The Stancor catalog that describes the P-6494 is here:

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CCwQFjAB&url=http%3A%2F%2Fwww.clarisonus.com%2FArchives%2FTrans%2FStancor61.pdf&ei=W2k4T5GJHaPd0QHU94HZBA&usg=AFQjCNGMl7-01CE3B7mzwVn8HrDgQXoniw&sig2=GNTtU2EciH4Ri_fEDxFCuA

or the shortened form:

http://x.co/ginB

Dave

:Hello All,
: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
:
:Thanks,
:
:Dave
:

Hello Again All,
I tried measuring the AC voltage from the secondary of the power transformer without the rectifier tube in place, and I see 301 volts AC per plate. So it could very well be working and the 0Z4 has a problem. My tube tester said there's a problem, but it's not specific about what it is. It's eye tube said "reject". This is the Seco 107. On one of the diodes the eye was wide open. Then after a while the output dropped off completely on both diodes.
So I'm going to search for another 0Z4 around here and try that and see if it works.

Thanks,

Dave
:Hello Again All,
: The Stancor catalog that describes the P-6494 is here:
:
:http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CCwQFjAB&url=http%3A%2F%2Fwww.clarisonus.com%2FArchives%2FTrans%2FStancor61.pdf&ei=W2k4T5GJHaPd0QHU94HZBA&usg=AFQjCNGMl7-01CE3B7mzwVn8HrDgQXoniw&sig2=GNTtU2EciH4Ri_fEDxFCuA
:
:or the shortened form:
:
:http://x.co/ginB
:
:Dave
:
::Hello All,
:: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
:: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
::
::Thanks,
::
::Dave
::
:
:

You can replace the 0Z4 with a silicon diode. Replace the buffer capacitor too with a 1600 rated cap.

Hi Dave

What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.

A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.

Norm

:Hello All,
: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
:
:Thanks,
:
:Dave
:

Norm,
What about current limiting resistors for the diodes?
It looks like the buffer capacitor was already replaced with a film type. I replaced all the others. OK I will replace the replaced capacitor and try it again.

Thanks,

Dave
:Hi Dave
:
: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
:
: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
:
:Norm
:
::Hello All,
:: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
:: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
::
::Thanks,
::
::Dave
::
:
:

Norm,
I replaced the buffer capacitor and a waft of smoke still comes out of the power transformer. The paper is all burned on the outside covering the windings. What would make it burn other than itself?

Thanks,

Dave
:Hi Dave
:
: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
:
: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
:
:Norm
:
::Hello All,
:: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
:: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
::
::Thanks,
::
::Dave
::
:
:

Norm,
Something is drawing way way too much current. The transformer gets very warm but it was one of my clip leads with a waft of smoke as the insulation was melting.
I don't think it should draw so much current.
Where should I check for excessive current draw?

Thanks,

Dave

:Hi Dave
:
: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
:
: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
:
:Norm
:
::Hello All,
:: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
:: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
::
::Thanks,
::
::Dave
::
:
:

Without a rectifier in it there is no B+ load. The buffer capacitor if was under rated is most likely why the transformer is now shorted. Check the primary and secondary from center taps to each end of the windings.

Norm,
Not only does the power transformer overheat, L9 is all burned too. Something is drawing way way too much current and I "think" it's the reverse solenoid. They draw 20 amps. I have to find where it's connected and cut the wire temporarily so I can listen to the radio.

Dave

:Hi Dave
:
: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
:
: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
:
:Norm
:
::Hello All,
:: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
:: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
::
::Thanks,
::
::Dave
::
:
:

Dave

We are hoping the vibrator transformer is good when it may be beyond use? Here are some vibrator transformers available. Look toward bottom of the list:

http://www.oldradioparts.com/2a23ffl.txt

Didn't think to ask, is the vibrator operating? If points are stuck could be putting DC right into the transformer?

Norm

:Norm,
: Not only does the power transformer overheat, L9 is all burned too. Something is drawing way way too much current and I "think" it's the reverse solenoid. They draw 20 amps. I have to find where it's connected and cut the wire temporarily so I can listen to the radio.
:
:Dave
:
::Hi Dave
::
:: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
::
:: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
::
::Norm
::
:::Hello All,
::: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
::: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
:::
:::Thanks,
:::
:::Dave
:::
::
::
:
:

Norm,
The vibrator is working fine. If the rectifier is unplugged, the power transformer (T1) puts out a "Healthy" 301-0-301 AC. I think it's ok.
Now L9 is also "burned" but it works. This is a Signal Seeker (I'm sure you have the service data, which is in Sams AR-8. I have it. If you have a copy you'll know what L9 is). Anyway, this set has 3 solenoids. You know how the return solenoid can get stuck on these (and draw 20 amps) sets, and this is what I think is happening. It hasn't anything to do with B+ at all. There's just a heavy load on the 12 volts. I use very fine clip leads so that if a set draws too much current, they will act like a fuse and melt. The smoke I saw, came from a melting clip lead. That's all. It's a good idea, and it has worked for me.

I'll let you know what I find as I continue with this interesting (refreshing?) set.

Thanks,

Dave

:Dave
:
: We are hoping the vibrator transformer is good when it may be beyond use? Here are some vibrator transformers available. Look toward bottom of the list:
:
:http://www.oldradioparts.com/2a23ffl.txt
:
: Didn't think to ask, is the vibrator operating? If points are stuck could be putting DC right into the transformer?
:
:Norm
:
::Norm,
:: Not only does the power transformer overheat, L9 is all burned too. Something is drawing way way too much current and I "think" it's the reverse solenoid. They draw 20 amps. I have to find where it's connected and cut the wire temporarily so I can listen to the radio.
::
::Dave
::
:::Hi Dave
:::
::: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
:::
::: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
:::
:::Norm
:::
::::Hello All,
:::: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
:::: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
::::
::::Thanks,
::::
::::Dave
::::
:::
:::
::
::
:
:

Dave,

Still think you have a problem in the B+ circuit(s) if the power transformer doesn't get hot and/or smoke with the rectifier pulled. Try making resistance checks of the B+ circuits starting from the 0Z4 cathode.

Clifton

:Norm,
: The vibrator is working fine. If the rectifier is unplugged, the power transformer (T1) puts out a "Healthy" 301-0-301 AC. I think it's ok.
: Now L9 is also "burned" but it works. This is a Signal Seeker (I'm sure you have the service data, which is in Sams AR-8. I have it. If you have a copy you'll know what L9 is). Anyway, this set has 3 solenoids. You know how the return solenoid can get stuck on these (and draw 20 amps) sets, and this is what I think is happening. It hasn't anything to do with B+ at all. There's just a heavy load on the 12 volts. I use very fine clip leads so that if a set draws too much current, they will act like a fuse and melt. The smoke I saw, came from a melting clip lead. That's all. It's a good idea, and it has worked for me.
:
:I'll let you know what I find as I continue with this interesting (refreshing?) set.
:
:Thanks,
:
:Dave
:
::Dave
::
:: We are hoping the vibrator transformer is good when it may be beyond use? Here are some vibrator transformers available. Look toward bottom of the list:
::
::http://www.oldradioparts.com/2a23ffl.txt
::
:: Didn't think to ask, is the vibrator operating? If points are stuck could be putting DC right into the transformer?
::
::Norm
::
:::Norm,
::: Not only does the power transformer overheat, L9 is all burned too. Something is drawing way way too much current and I "think" it's the reverse solenoid. They draw 20 amps. I have to find where it's connected and cut the wire temporarily so I can listen to the radio.
:::
:::Dave
:::
::::Hi Dave
::::
:::: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
::::
:::: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
::::
::::Norm
::::
:::::Hello All,
::::: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
::::: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
:::::
:::::Thanks,
:::::
:::::Dave
:::::
::::
::::
:::
:::
::
::
:
:

Dave

Is it really an 0Z4? Don't think an 0Z4 can draw enough current to cause this type of problem. Have you tried another 0Z4? Take the 0Z4 apart. Maybe someone put diodes inside and they shorted?

To open an 0Z4 just bend back the crimps at the base and pry it apart. The wire to pin #1 will break but it will come apart.

Norm

:Dave,
:
:Still think you have a problem in the B+ circuit(s) if the power transformer doesn't get hot and/or smoke with the rectifier pulled. Try making resistance checks of the B+ circuits starting from the 0Z4 cathode.
:
:Clifton
:
::Norm,
:: The vibrator is working fine. If the rectifier is unplugged, the power transformer (T1) puts out a "Healthy" 301-0-301 AC. I think it's ok.
:: Now L9 is also "burned" but it works. This is a Signal Seeker (I'm sure you have the service data, which is in Sams AR-8. I have it. If you have a copy you'll know what L9 is). Anyway, this set has 3 solenoids. You know how the return solenoid can get stuck on these (and draw 20 amps) sets, and this is what I think is happening. It hasn't anything to do with B+ at all. There's just a heavy load on the 12 volts. I use very fine clip leads so that if a set draws too much current, they will act like a fuse and melt. The smoke I saw, came from a melting clip lead. That's all. It's a good idea, and it has worked for me.
::
::I'll let you know what I find as I continue with this interesting (refreshing?) set.
::
::Thanks,
::
::Dave
::
:::Dave
:::
::: We are hoping the vibrator transformer is good when it may be beyond use? Here are some vibrator transformers available. Look toward bottom of the list:
:::
:::http://www.oldradioparts.com/2a23ffl.txt
:::
::: Didn't think to ask, is the vibrator operating? If points are stuck could be putting DC right into the transformer?
:::
:::Norm
:::
::::Norm,
:::: Not only does the power transformer overheat, L9 is all burned too. Something is drawing way way too much current and I "think" it's the reverse solenoid. They draw 20 amps. I have to find where it's connected and cut the wire temporarily so I can listen to the radio.
::::
::::Dave
::::
:::::Hi Dave
:::::
::::: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
:::::
::::: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
:::::
:::::Norm
:::::
::::::Hello All,
:::::: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
:::::: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
::::::
::::::Thanks,
::::::
::::::Dave
::::::
:::::
:::::
::::
::::
:::
:::
::
::
:
:

Dave

I sent a copy of this to Meade for his comments.

Norm

:Dave
:
: Is it really an 0Z4? Don't think an 0Z4 can draw enough current to cause this type of problem. Have you tried another 0Z4? Take the 0Z4 apart. Maybe someone put diodes inside and they shorted?
:
: To open an 0Z4 just bend back the crimps at the base and pry it apart. The wire to pin #1 will break but it will come apart.
:
:Norm
:
::Dave,
::
::Still think you have a problem in the B+ circuit(s) if the power transformer doesn't get hot and/or smoke with the rectifier pulled. Try making resistance checks of the B+ circuits starting from the 0Z4 cathode.
::
::Clifton
::
:::Norm,
::: The vibrator is working fine. If the rectifier is unplugged, the power transformer (T1) puts out a "Healthy" 301-0-301 AC. I think it's ok.
::: Now L9 is also "burned" but it works. This is a Signal Seeker (I'm sure you have the service data, which is in Sams AR-8. I have it. If you have a copy you'll know what L9 is). Anyway, this set has 3 solenoids. You know how the return solenoid can get stuck on these (and draw 20 amps) sets, and this is what I think is happening. It hasn't anything to do with B+ at all. There's just a heavy load on the 12 volts. I use very fine clip leads so that if a set draws too much current, they will act like a fuse and melt. The smoke I saw, came from a melting clip lead. That's all. It's a good idea, and it has worked for me.
:::
:::I'll let you know what I find as I continue with this interesting (refreshing?) set.
:::
:::Thanks,
:::
:::Dave
:::
::::Dave
::::
:::: We are hoping the vibrator transformer is good when it may be beyond use? Here are some vibrator transformers available. Look toward bottom of the list:
::::
::::http://www.oldradioparts.com/2a23ffl.txt
::::
:::: Didn't think to ask, is the vibrator operating? If points are stuck could be putting DC right into the transformer?
::::
::::Norm
::::
:::::Norm,
::::: Not only does the power transformer overheat, L9 is all burned too. Something is drawing way way too much current and I "think" it's the reverse solenoid. They draw 20 amps. I have to find where it's connected and cut the wire temporarily so I can listen to the radio.
:::::
:::::Dave
:::::
::::::Hi Dave
::::::
:::::: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
::::::
:::::: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
::::::
::::::Norm
::::::
:::::::Hello All,
::::::: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
::::::: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
:::::::
:::::::Thanks,
:::::::
:::::::Dave
:::::::
::::::
::::::
:::::
:::::
::::
::::
:::
:::
::
::
:
:

Norm,
It's not drawing too much current. The current is being pulled through the A circuit on the primary side of the transformer. But I am about 99% positive, something else like a solenoid coil that's pulling all the current through there. The vibrator, rectifier and transformer are fine. I will take another look at it later.
That's like saying that because a resistor is overheating and burning, that the resistor is the cause problem. But, of course, that's not the case. The burned resistor, or transformer, in this case, is just a symptom. Something else is drawing too much current. The symptoms are a very warm power transformer and a very warm L9, but they are most likely NOT the problem. When the problem is found and corrected, the transformer (T1) and L9 will stop overheating. That's what I think will happen. This isn't the first time I've seen this problem.

Thanks,

Dave

:Dave
:
: Is it really an 0Z4? Don't think an 0Z4 can draw enough current to cause this type of problem. Have you tried another 0Z4? Take the 0Z4 apart. Maybe someone put diodes inside and they shorted?
:
: To open an 0Z4 just bend back the crimps at the base and pry it apart. The wire to pin #1 will break but it will come apart.
:
:Norm
:
::Dave,
::
::Still think you have a problem in the B+ circuit(s) if the power transformer doesn't get hot and/or smoke with the rectifier pulled. Try making resistance checks of the B+ circuits starting from the 0Z4 cathode.
::
::Clifton
::
:::Norm,
::: The vibrator is working fine. If the rectifier is unplugged, the power transformer (T1) puts out a "Healthy" 301-0-301 AC. I think it's ok.
::: Now L9 is also "burned" but it works. This is a Signal Seeker (I'm sure you have the service data, which is in Sams AR-8. I have it. If you have a copy you'll know what L9 is). Anyway, this set has 3 solenoids. You know how the return solenoid can get stuck on these (and draw 20 amps) sets, and this is what I think is happening. It hasn't anything to do with B+ at all. There's just a heavy load on the 12 volts. I use very fine clip leads so that if a set draws too much current, they will act like a fuse and melt. The smoke I saw, came from a melting clip lead. That's all. It's a good idea, and it has worked for me.
:::
:::I'll let you know what I find as I continue with this interesting (refreshing?) set.
:::
:::Thanks,
:::
:::Dave
:::
::::Dave
::::
:::: We are hoping the vibrator transformer is good when it may be beyond use? Here are some vibrator transformers available. Look toward bottom of the list:
::::
::::http://www.oldradioparts.com/2a23ffl.txt
::::
:::: Didn't think to ask, is the vibrator operating? If points are stuck could be putting DC right into the transformer?
::::
::::Norm
::::
:::::Norm,
::::: Not only does the power transformer overheat, L9 is all burned too. Something is drawing way way too much current and I "think" it's the reverse solenoid. They draw 20 amps. I have to find where it's connected and cut the wire temporarily so I can listen to the radio.
:::::
:::::Dave
:::::
::::::Hi Dave
::::::
:::::: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
::::::
:::::: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
::::::
::::::Norm
::::::
:::::::Hello All,
::::::: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
::::::: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
:::::::
:::::::Thanks,
:::::::
:::::::Dave
:::::::
::::::
::::::
:::::
:::::
::::
::::
:::
:::
::
::
:
:

Dave,

I don't have the schematic for the radio, but, I would think the only thing that should be causing current to flow in the primary halves of the power transformer would be the vibrator or interrupter. Low voltage current for filaments, solenoids and etc should be supplied from another circuit and not through the primary halves of the power transformer. Is it possible someone attempted repairs and made a wiring error?

Clifton

:Norm,
: It's not drawing too much current. The current is being pulled through the A circuit on the primary side of the transformer. But I am about 99% positive, something else like a solenoid coil that's pulling all the current through there. The vibrator, rectifier and transformer are fine. I will take another look at it later.
: That's like saying that because a resistor is overheating and burning, that the resistor is the cause problem. But, of course, that's not the case. The burned resistor, or transformer, in this case, is just a symptom. Something else is drawing too much current. The symptoms are a very warm power transformer and a very warm L9, but they are most likely NOT the problem. When the problem is found and corrected, the transformer (T1) and L9 will stop overheating. That's what I think will happen. This isn't the first time I've seen this problem.
:
:Thanks,
:
:Dave
:
::Dave
::
:: Is it really an 0Z4? Don't think an 0Z4 can draw enough current to cause this type of problem. Have you tried another 0Z4? Take the 0Z4 apart. Maybe someone put diodes inside and they shorted?
::
:: To open an 0Z4 just bend back the crimps at the base and pry it apart. The wire to pin #1 will break but it will come apart.
::
::Norm
::
:::Dave,
:::
:::Still think you have a problem in the B+ circuit(s) if the power transformer doesn't get hot and/or smoke with the rectifier pulled. Try making resistance checks of the B+ circuits starting from the 0Z4 cathode.
:::
:::Clifton
:::
::::Norm,
:::: The vibrator is working fine. If the rectifier is unplugged, the power transformer (T1) puts out a "Healthy" 301-0-301 AC. I think it's ok.
:::: Now L9 is also "burned" but it works. This is a Signal Seeker (I'm sure you have the service data, which is in Sams AR-8. I have it. If you have a copy you'll know what L9 is). Anyway, this set has 3 solenoids. You know how the return solenoid can get stuck on these (and draw 20 amps) sets, and this is what I think is happening. It hasn't anything to do with B+ at all. There's just a heavy load on the 12 volts. I use very fine clip leads so that if a set draws too much current, they will act like a fuse and melt. The smoke I saw, came from a melting clip lead. That's all. It's a good idea, and it has worked for me.
::::
::::I'll let you know what I find as I continue with this interesting (refreshing?) set.
::::
::::Thanks,
::::
::::Dave
::::
:::::Dave
:::::
::::: We are hoping the vibrator transformer is good when it may be beyond use? Here are some vibrator transformers available. Look toward bottom of the list:
:::::
:::::http://www.oldradioparts.com/2a23ffl.txt
:::::
::::: Didn't think to ask, is the vibrator operating? If points are stuck could be putting DC right into the transformer?
:::::
:::::Norm
:::::
::::::Norm,
:::::: Not only does the power transformer overheat, L9 is all burned too. Something is drawing way way too much current and I "think" it's the reverse solenoid. They draw 20 amps. I have to find where it's connected and cut the wire temporarily so I can listen to the radio.
::::::
::::::Dave
::::::
:::::::Hi Dave
:::::::
::::::: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
:::::::
::::::: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
:::::::
:::::::Norm
:::::::
::::::::Hello All,
:::::::: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
:::::::: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
::::::::
::::::::Thanks,
::::::::
::::::::Dave
::::::::
:::::::
:::::::
::::::
::::::
:::::
:::::
::::
::::
:::
:::
::
::
:
:

Dave,
You will have heavy current draw on the “A” line through choke coil L8 (filament choke) if either the treadle or power solenoid is hung-up and still powered. Power for the solenoids goes through L8, contacts on the search relay M9, through the solenoids and to ground through the treadle and power switches M5. Possible problems are welded contacts on the search relay, and defective switches M5 (actually two separate switch bodies clipped together). Possible problems with the switches are burned or welded contacts, and most likely burned and weakened locating springs inside the switch bodies due to prolonged current flow through the solenoids. The solenoids should hit and release almost instantly. It only takes a second for things to start burning up. Not enough current in the bench supply or use of too small a wire to power the radio could be part of the problem.

Meade

*****************************************

:Norm,
: It's not drawing too much current. The current is being pulled through the A circuit on the primary side of the transformer. But I am about 99% positive, something else like a solenoid coil that's pulling all the current through there. The vibrator, rectifier and transformer are fine. I will take another look at it later.
: That's like saying that because a resistor is overheating and burning, that the resistor is the cause problem. But, of course, that's not the case. The burned resistor, or transformer, in this case, is just a symptom. Something else is drawing too much current. The symptoms are a very warm power transformer and a very warm L9, but they are most likely NOT the problem. When the problem is found and corrected, the transformer (T1) and L9 will stop overheating. That's what I think will happen. This isn't the first time I've seen this problem.
:
:Thanks,
:
:Dave
:
::Dave
::
:: Is it really an 0Z4? Don't think an 0Z4 can draw enough current to cause this type of problem. Have you tried another 0Z4? Take the 0Z4 apart. Maybe someone put diodes inside and they shorted?
::
:: To open an 0Z4 just bend back the crimps at the base and pry it apart. The wire to pin #1 will break but it will come apart.
::
::Norm
::
:::Dave,
:::
:::Still think you have a problem in the B+ circuit(s) if the power transformer doesn't get hot and/or smoke with the rectifier pulled. Try making resistance checks of the B+ circuits starting from the 0Z4 cathode.
:::
:::Clifton
:::
::::Norm,
:::: The vibrator is working fine. If the rectifier is unplugged, the power transformer (T1) puts out a "Healthy" 301-0-301 AC. I think it's ok.
:::: Now L9 is also "burned" but it works. This is a Signal Seeker (I'm sure you have the service data, which is in Sams AR-8. I have it. If you have a copy you'll know what L9 is). Anyway, this set has 3 solenoids. You know how the return solenoid can get stuck on these (and draw 20 amps) sets, and this is what I think is happening. It hasn't anything to do with B+ at all. There's just a heavy load on the 12 volts. I use very fine clip leads so that if a set draws too much current, they will act like a fuse and melt. The smoke I saw, came from a melting clip lead. That's all. It's a good idea, and it has worked for me.
::::
::::I'll let you know what I find as I continue with this interesting (refreshing?) set.
::::
::::Thanks,
::::
::::Dave
::::
:::::Dave
:::::
::::: We are hoping the vibrator transformer is good when it may be beyond use? Here are some vibrator transformers available. Look toward bottom of the list:
:::::
:::::http://www.oldradioparts.com/2a23ffl.txt
:::::
::::: Didn't think to ask, is the vibrator operating? If points are stuck could be putting DC right into the transformer?
:::::
:::::Norm
:::::
::::::Norm,
:::::: Not only does the power transformer overheat, L9 is all burned too. Something is drawing way way too much current and I "think" it's the reverse solenoid. They draw 20 amps. I have to find where it's connected and cut the wire temporarily so I can listen to the radio.
::::::
::::::Dave
::::::
:::::::Hi Dave
:::::::
::::::: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
:::::::
::::::: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
:::::::
:::::::Norm
:::::::
::::::::Hello All,
:::::::: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
:::::::: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
::::::::
::::::::Thanks,
::::::::
::::::::Dave
::::::::
:::::::
:::::::
::::::
::::::
:::::
:::::
::::
::::
:::
:::
::
::
:
:

MAG,
I tried silicon diodes just to test it. It worked for about a minute and something popped and sparked, and it stopped working. The diodes are still fine. Checking the secondary, I have 270 ohms on one half and 10 K ohms on the other half. I don't think that the power transformer is working.
I asked about dropping resistors and all I heard was to try silicon diodes. So I think I need to look for a power transformer now, or was it ok with two diodes and no dropping resistor? But it does seem now like the 0Z4 wasn't working. My tube tester said there was a problem with one of the diodes in it. So I'm not sure what happened, but I have an idea (inrush current?).
I think I need to find a replacement power transformer (vibrator type power transformer).

Thanks,

Dave
:Dave,
:You will have heavy current draw on the “A” line through choke coil L8 (filament choke) if either the treadle or power solenoid is hung-up and still powered. Power for the solenoids goes through L8, contacts on the search relay M9, through the solenoids and to ground through the treadle and power switches M5. Possible problems are welded contacts on the search relay, and defective switches M5 (actually two separate switch bodies clipped together). Possible problems with the switches are burned or welded contacts, and most likely burned and weakened locating springs inside the switch bodies due to prolonged current flow through the solenoids. The solenoids should hit and release almost instantly. It only takes a second for things to start burning up. Not enough current in the bench supply or use of too small a wire to power the radio could be part of the problem.
:
:Meade
:
:*****************************************
:
:
:
::Norm,
:: It's not drawing too much current. The current is being pulled through the A circuit on the primary side of the transformer. But I am about 99% positive, something else like a solenoid coil that's pulling all the current through there. The vibrator, rectifier and transformer are fine. I will take another look at it later.
:: That's like saying that because a resistor is overheating and burning, that the resistor is the cause problem. But, of course, that's not the case. The burned resistor, or transformer, in this case, is just a symptom. Something else is drawing too much current. The symptoms are a very warm power transformer and a very warm L9, but they are most likely NOT the problem. When the problem is found and corrected, the transformer (T1) and L9 will stop overheating. That's what I think will happen. This isn't the first time I've seen this problem.
::
::Thanks,
::
::Dave
::
:::Dave
:::
::: Is it really an 0Z4? Don't think an 0Z4 can draw enough current to cause this type of problem. Have you tried another 0Z4? Take the 0Z4 apart. Maybe someone put diodes inside and they shorted?
:::
::: To open an 0Z4 just bend back the crimps at the base and pry it apart. The wire to pin #1 will break but it will come apart.
:::
:::Norm
:::
::::Dave,
::::
::::Still think you have a problem in the B+ circuit(s) if the power transformer doesn't get hot and/or smoke with the rectifier pulled. Try making resistance checks of the B+ circuits starting from the 0Z4 cathode.
::::
::::Clifton
::::
:::::Norm,
::::: The vibrator is working fine. If the rectifier is unplugged, the power transformer (T1) puts out a "Healthy" 301-0-301 AC. I think it's ok.
::::: Now L9 is also "burned" but it works. This is a Signal Seeker (I'm sure you have the service data, which is in Sams AR-8. I have it. If you have a copy you'll know what L9 is). Anyway, this set has 3 solenoids. You know how the return solenoid can get stuck on these (and draw 20 amps) sets, and this is what I think is happening. It hasn't anything to do with B+ at all. There's just a heavy load on the 12 volts. I use very fine clip leads so that if a set draws too much current, they will act like a fuse and melt. The smoke I saw, came from a melting clip lead. That's all. It's a good idea, and it has worked for me.
:::::
:::::I'll let you know what I find as I continue with this interesting (refreshing?) set.
:::::
:::::Thanks,
:::::
:::::Dave
:::::
::::::Dave
::::::
:::::: We are hoping the vibrator transformer is good when it may be beyond use? Here are some vibrator transformers available. Look toward bottom of the list:
::::::
::::::http://www.oldradioparts.com/2a23ffl.txt
::::::
:::::: Didn't think to ask, is the vibrator operating? If points are stuck could be putting DC right into the transformer?
::::::
::::::Norm
::::::
:::::::Norm,
::::::: Not only does the power transformer overheat, L9 is all burned too. Something is drawing way way too much current and I "think" it's the reverse solenoid. They draw 20 amps. I have to find where it's connected and cut the wire temporarily so I can listen to the radio.
:::::::
:::::::Dave
:::::::
::::::::Hi Dave
::::::::
:::::::: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
::::::::
:::::::: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
::::::::
::::::::Norm
::::::::
:::::::::Hello All,
::::::::: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
::::::::: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
:::::::::
:::::::::Thanks,
:::::::::
:::::::::Dave
:::::::::
::::::::
::::::::
:::::::
:::::::
::::::
::::::
:::::
:::::
::::
::::
:::
:::
::
::
:
:

No resistors are needed for the silicon diodes.

Warren,
I'm wrong. The 10K is the resistor. The secondary is fine!!! I need to connect the two diodes correctly. Yes, I know how. I just made a mistake. But it's ok. I'll re-connect correctly and try again.
I have no idea what sparked. I will have to see it spark again. Maybe L9 touched the chassis momentarily because the paper cover is off. I have it pulled up above the chassis temporarily. The chassis is upside down.
That's some rugged power transformer!

Thanks very much,

Dave
:No resistors are needed for the silicon diodes.
:

Warren,
It sounds a bit hummy. Did one of the filter capacitors crap out on me? The secondaries are good very good. I'm sure I have the diodes connected correctly. Each end of the entire transformer connects the the positive end of each diode. The negative end of both diodes are connected together and this is where B+ comes from. B+ is connected to the positive of the first filter capacitor. I've done this too many times. It should not be hummy. I'll keep checking. But I'm relieved that the power transformer measures good. I was measuring in the wrong place.
I think I'd better order an 0Z4. Also, I'll soon have a solid state vibrator. Maybe the vibrator isn't working correctly?

Thanks,

Dave
:Warren,
: I'm wrong. The 10K is the resistor. The secondary is fine!!! I need to connect the two diodes correctly. Yes, I know how. I just made a mistake. But it's ok. I'll re-connect correctly and try again.
: I have no idea what sparked. I will have to see it spark again. Maybe L9 touched the chassis momentarily because the paper cover is off. I have it pulled up above the chassis temporarily. The chassis is upside down.
: That's some rugged power transformer!
:
:Thanks very much,
:
:Dave
::No resistors are needed for the silicon diodes.
::
:
:

Warren,
Yes, one of the new capacitors crapped out. I replaced it and no more hummy sound. But it lacks oomph because there's still something in the A circuit that's drawing way way too much current, taking it away from the tubes which don't even get warm. They should be hot to the touch and they aren't. L9 gets really really hot. So something, I have no idea what, is drawing too much current away from the filaments. We have proven beyond the shadow of a doubt that the power transformer is ok.
I'm ordering a new 0Z4 and dial belt material because the dial belt is slipping.
Now that the power transformer is ok. I need to start a new thread called "1958 Cadillac Car Radio, excessive A+ current draw".

Thanks,

Dave

:Warren,
: It sounds a bit hummy. Did one of the filter capacitors crap out on me? The secondaries are good very good. I'm sure I have the diodes connected correctly. Each end of the entire transformer connects the the positive end of each diode. The negative end of both diodes are connected together and this is where B+ comes from. B+ is connected to the positive of the first filter capacitor. I've done this too many times. It should not be hummy. I'll keep checking. But I'm relieved that the power transformer measures good. I was measuring in the wrong place.
: I think I'd better order an 0Z4. Also, I'll soon have a solid state vibrator. Maybe the vibrator isn't working correctly?
:
:Thanks,
:
:Dave
::Warren,
:: I'm wrong. The 10K is the resistor. The secondary is fine!!! I need to connect the two diodes correctly. Yes, I know how. I just made a mistake. But it's ok. I'll re-connect correctly and try again.
:: I have no idea what sparked. I will have to see it spark again. Maybe L9 touched the chassis momentarily because the paper cover is off. I have it pulled up above the chassis temporarily. The chassis is upside down.
:: That's some rugged power transformer!
::
::Thanks very much,
::
::Dave
:::No resistors are needed for the silicon diodes.
:::
::
::
:
:

Norm,
There are ZERO 12 volt vibrator power transformers on that page.

Thanks,

Dave
:Dave
:
: We are hoping the vibrator transformer is good when it may be beyond use? Here are some vibrator transformers available. Look toward bottom of the list:
:
:http://www.oldradioparts.com/2a23ffl.txt
:
: Didn't think to ask, is the vibrator operating? If points are stuck could be putting DC right into the transformer?
:
:Norm
:
::Norm,
:: Not only does the power transformer overheat, L9 is all burned too. Something is drawing way way too much current and I "think" it's the reverse solenoid. They draw 20 amps. I have to find where it's connected and cut the wire temporarily so I can listen to the radio.
::
::Dave
::
:::Hi Dave
:::
::: What are you using to power the transformer? If 60 cycles it will get hot. Vibrator transformers operate around 115 cycles. Higher frequency, cooler operation. Many of us have used 60 cycles but expect transformer heating.
:::
::: A bad 0Z4 will not fire. Never heard of one shorting damaging a transformer. As Warren said, replace the buffer cap. It could cause excessive transformer loading.
:::
:::Norm
:::
::::Hello All,
:::: This one arrived with burned power transformer (aka. Vibrator Transformer) which overheats when current is connected to it. It burns too. So unfortunately it has to be replaced. Does anyone know where I might find one of these? This is either Model 7270405 or 7270555.
:::: The GM part number is 7271233, Stancor: P-6497. I'll check everything I can to rule out this problem but it sure looks like the power transformer needs to be replaced. I've had this problem before in radios. The odor and temperature is exactly the same.
::::
::::Thanks,
::::
::::Dave
::::
:::
:::
::
::
:
: