I have just gotten through re-capping two of these neat radios from the thirties. One radio works just fine, but the other has a low background AC hum with the power transformer starting to over-heat after the radio has been on for two or three minutes. I have verified the circuits and am asking if anyone has any ideas about what the problem may be, or maybe I just have a bad transformer. Neither radio was working when I got them. Any advice would be greatly appreciated.
Thanks,
Bill

:I have just gotten through re-capping two of these neat radios from the thirties. One radio works just fine, but the other has a low background AC hum with the power transformer starting to over-heat after the radio has been on for two or three minutes. I have verified the circuits and am asking if anyone has any ideas about what the problem may be, or maybe I just have a bad transformer. Neither radio was working when I got them. Any advice would be greatly appreciated.
:Thanks,
Bill
I have resolved the background hum, but still have the overheating transformer??

:Bill

Hi Bill

Pull the 5W4 rectifier rectifier and let your radio operate 30 minutes. This removes load from the B+ supply. After 30 minutes the transformer should only be slightly warm. If hot, transformer will need to be replaced.

Voltage on each plate of the rectifier tube should be the same. If it's not a winding is shorted.

Hum and excessive current drain could be caused by the 6F6 circuit. The tube could be bad or grid #1 resistor high in value. This causes the tube to draw excessive current, heating your transformer and causing hum.

Norm

::I have just gotten through re-capping two of these neat radios from the thirties. One radio works just fine, but the other has a low background AC hum with the power transformer starting to over-heat after the radio has been on for two or three minutes. I have verified the circuits and am asking if anyone has any ideas about what the problem may be, or maybe I just have a bad transformer. Neither radio was working when I got them. Any advice would be greatly appreciated.
::Thanks,
:Bill
:I have resolved the background hum, but still have the overheating transformer??
:
::Bill

Thanks, I'll give this a try.
Bill

:Hi Bill
:
:Pull the 5W4 rectifier rectifier and let your radio operate 30 minutes. This removes load from the B+ supply. After 30 minutes the transformer should only be slightly warm. If hot, transformer will need to be replaced.
:
:Voltage on each plate of the rectifier tube should be the same. If it's not a winding is shorted.
:
:Hum and excessive current drain could be caused by the 6F6 circuit. The tube could be bad or grid #1 resistor high in value. This causes the tube to draw excessive current, heating your transformer and causing hum.
:
:Norm
:
:::I have just gotten through re-capping two of these neat radios from the thirties. One radio works just fine, but the other has a low background AC hum with the power transformer starting to over-heat after the radio has been on for two or three minutes. I have verified the circuits and am asking if anyone has any ideas about what the problem may be, or maybe I just have a bad transformer. Neither radio was working when I got them. Any advice would be greatly appreciated.
:::Thanks,
::Bill
::I have resolved the background hum, but still have the overheating transformer??
::
:::Bill

:Hi Bill
:
:Pull the 5W4 rectifier rectifier and let your radio operate 30 minutes. This removes load from the B+ supply. After 30 minutes the transformer should only be slightly warm. If hot, transformer will need to be replaced.
:
:Voltage on each plate of the rectifier tube should be the same. If it's not a winding is shorted.
:
:Hum and excessive current drain could be caused by the 6F6 circuit. The tube could be bad or grid #1 resistor high in value. This causes the tube to draw excessive current, heating your transformer and causing hum.
:
:Norm
:
Hi, Norm. I pulled the 5W4 and turned the radio on. After about three minutes, I heard the trans heat and start crackling as before. I need to replace it. Thanks for your help.

:::I have just gotten through re-capping two of these neat radios from the thirties. One radio works just fine, but the other has a low background AC hum with the power transformer starting to over-heat after the radio has been on for two or three minutes. I have verified the circuits and am asking if anyone has any ideas about what the problem may be, or maybe I just have a bad transformer. Neither radio was working when I got them. Any advice would be greatly appreciated.
:::Thanks,
::Bill
::I have resolved the background hum, but still have the overheating transformer??
::
:::Bill

:Hi, Norm. I appreciate the advice. The schematics describe it as a "Universal" transformer with a "V" rating. Does anyone know a source for a replacement?
Thanks

::Hi Bill
::
::Pull the 5W4 rectifier rectifier and let your radio operate 30 minutes. This removes load from the B+ supply. After 30 minutes the transformer should only be slightly warm. If hot, transformer will need to be replaced.
::
::Voltage on each plate of the rectifier tube should be the same. If it's not a winding is shorted.
::
::Hum and excessive current drain could be caused by the 6F6 circuit. The tube could be bad or grid #1 resistor high in value. This causes the tube to draw excessive current, heating your transformer and causing hum.
::
::Norm
::
:Hi, Norm. I pulled the 5W4 and turned the radio on. After about three minutes, I heard the trans heat and start crackling as before. I need to replace it. Thanks for your help.
:
::::I have just gotten through re-capping two of these neat radios from the thirties. One radio works just fine, but the other has a low background AC hum with the power transformer starting to over-heat after the radio has been on for two or three minutes. I have verified the circuits and am asking if anyone has any ideas about what the problem may be, or maybe I just have a bad transformer. Neither radio was working when I got them. Any advice would be greatly appreciated.
::::Thanks,
:::Bill
:::I have resolved the background hum, but still have the overheating transformer??
:::
::::Bill

Hi Bill

Look at this site for a replacement transformer:

http://www.oldradioparts.com/2a23efl.txt

These should be the best prices. Universal doesn't mean much. Usually a transformer that can be used in different radios often with selectable taps. You need a transformer with 6.3 volts, 5 volt and high voltage center tapped windings. Current should match or exceed tube requirements. You can go with higher ratings but be sure it's fits on the radio chassis.

Norm

::Hi, Norm. I appreciate the advice. The schematics describe it as a "Universal" transformer with a "V" rating. Does anyone know a source for a replacement?
:Thanks
:
:::Hi Bill
:::
:::Pull the 5W4 rectifier rectifier and let your radio operate 30 minutes. This removes load from the B+ supply. After 30 minutes the transformer should only be slightly warm. If hot, transformer will need to be replaced.
:::
:::Voltage on each plate of the rectifier tube should be the same. If it's not a winding is shorted.
:::
:::Hum and excessive current drain could be caused by the 6F6 circuit. The tube could be bad or grid #1 resistor high in value. This causes the tube to draw excessive current, heating your transformer and causing hum.
:::
:::Norm
:::
::Hi, Norm. I pulled the 5W4 and turned the radio on. After about three minutes, I heard the trans heat and start crackling as before. I need to replace it. Thanks for your help.
::
:::::I have just gotten through re-capping two of these neat radios from the thirties. One radio works just fine, but the other has a low background AC hum with the power transformer starting to over-heat after the radio has been on for two or three minutes. I have verified the circuits and am asking if anyone has any ideas about what the problem may be, or maybe I just have a bad transformer. Neither radio was working when I got them. Any advice would be greatly appreciated.
:::::Thanks,
::::Bill
::::I have resolved the background hum, but still have the overheating transformer??
::::
:::::Bill

Thanks! Great site

:Hi Bill
:
: Look at this site for a replacement transformer:
:
:http://www.oldradioparts.com/2a23efl.txt
:
: These should be the best prices. Universal doesn't mean much. Usually a transformer that can be used in different radios often with selectable taps. You need a transformer with 6.3 volts, 5 volt and high voltage center tapped windings. Current should match or exceed tube requirements. You can go with higher ratings but be sure it's fits on the radio chassis.
:
:Norm
:
:::Hi, Norm. I appreciate the advice. The schematics describe it as a "Universal" transformer with a "V" rating. Does anyone know a source for a replacement?
::Thanks
::
::::Hi Bill
::::
::::Pull the 5W4 rectifier rectifier and let your radio operate 30 minutes. This removes load from the B+ supply. After 30 minutes the transformer should only be slightly warm. If hot, transformer will need to be replaced.
::::
::::Voltage on each plate of the rectifier tube should be the same. If it's not a winding is shorted.
::::
::::Hum and excessive current drain could be caused by the 6F6 circuit. The tube could be bad or grid #1 resistor high in value. This causes the tube to draw excessive current, heating your transformer and causing hum.
::::
::::Norm
::::
:::Hi, Norm. I pulled the 5W4 and turned the radio on. After about three minutes, I heard the trans heat and start crackling as before. I need to replace it. Thanks for your help.
:::
::::::I have just gotten through re-capping two of these neat radios from the thirties. One radio works just fine, but the other has a low background AC hum with the power transformer starting to over-heat after the radio has been on for two or three minutes. I have verified the circuits and am asking if anyone has any ideas about what the problem may be, or maybe I just have a bad transformer. Neither radio was working when I got them. Any advice would be greatly appreciated.
::::::Thanks,
:::::Bill
:::::I have resolved the background hum, but still have the overheating transformer??
:::::
::::::Bill

Hi Bill,
Sometimes a "Universal" power transformer will indicate that it is designed for more than one line voltage, usually with a switch to select which voltage. These were usually in models designed for export to other countries. For example, I have a Zenith 6S52A, which has a "universal" power transformer which can be operated off your choice of 110v, 125v, 150v, 200v, 220v, or 250v AC. Power transformers like this will have multiple taps on the primary side. These can be replaced with standard power transformers with 117v primary, following Norm's recommendations.

Poston

:Thanks! Great site
:
::Hi Bill
::
:: Look at this site for a replacement transformer:
::
::http://www.oldradioparts.com/2a23efl.txt
::
:: These should be the best prices. Universal doesn't mean much. Usually a transformer that can be used in different radios often with selectable taps. You need a transformer with 6.3 volts, 5 volt and high voltage center tapped windings. Current should match or exceed tube requirements. You can go with higher ratings but be sure it's fits on the radio chassis.
::
::Norm
::
::::Hi, Norm. I appreciate the advice. The schematics describe it as a "Universal" transformer with a "V" rating. Does anyone know a source for a replacement?
:::Thanks
:::
:::::Hi Bill
:::::
:::::Pull the 5W4 rectifier rectifier and let your radio operate 30 minutes. This removes load from the B+ supply. After 30 minutes the transformer should only be slightly warm. If hot, transformer will need to be replaced.
:::::
:::::Voltage on each plate of the rectifier tube should be the same. If it's not a winding is shorted.
:::::
:::::Hum and excessive current drain could be caused by the 6F6 circuit. The tube could be bad or grid #1 resistor high in value. This causes the tube to draw excessive current, heating your transformer and causing hum.
:::::
:::::Norm
:::::
::::Hi, Norm. I pulled the 5W4 and turned the radio on. After about three minutes, I heard the trans heat and start crackling as before. I need to replace it. Thanks for your help.
::::
:::::::I have just gotten through re-capping two of these neat radios from the thirties. One radio works just fine, but the other has a low background AC hum with the power transformer starting to over-heat after the radio has been on for two or three minutes. I have verified the circuits and am asking if anyone has any ideas about what the problem may be, or maybe I just have a bad transformer. Neither radio was working when I got them. Any advice would be greatly appreciated.
:::::::Thanks,
::::::Bill
::::::I have resolved the background hum, but still have the overheating transformer??
::::::
:::::::Bill