smokeing transformers

12/29/2009 3:49:22 PMmichael rybikowsky

have been collecting tube type german radios for awhile. I need help. three of them when turned on the transformers smoke.I have bought vintage repair books,but they are all weak on trouble shooting, could use some advice. thanks happy new year. miker

12/29/2009 6:55:51 PMBill G.

Hi Michael,

I am sure it won't surprise you that there are two caouses of this problem. Cause 1, the transformwe is overloaded. Cause 2, the transformer just went bad.

The first step is to pull out all the tubes and plug it in. If it smokes, the transformer is ruined. It may have just gone defective or it may have been ruined due to a prolonged exposure to an overload condition.
There exists a small possiblility that there is a short in the filament wiring. That can be checked by disconnecting one of the transformer's filament leads and ohming out the filament circuit. At that point it should read higher than 100K.
If the transformer runs cool then you have caught the problem in time. The circuitry is overloading the transformer.
If it looks like your transformers are OK, we can pick up from there. If the transformers are bad, you may want to find other German radios!

Best Regards,

Bill Grimm

12/29/2009 8:53:50 PMThomas Dermody

...Though transformers with 120 and 240 volt windings are readily available.

Most often, if an overload condition exists, it's due to capacitors. Electrolytics should have leakage in the millions of ohms or better (the ohmmeter check can be quite inaccurate here, because sometimes an electrolytic just needs a little reform, and isn't really bad), and all other capacitors should have absolutely no leakage. Best checked with a high voltage capacitor checker, but can be done fairly well with an ohmmeter, too, if it is a high impedance meter.

T.

12/30/2009 5:04:42 AMJohnnysan

:...Though transformers with 120 and 240 volt windings are readily available.
:
:Most often, if an overload condition exists, it's due to capacitors. Electrolytics should have leakage in the millions of ohms or better (the ohmmeter check can be quite inaccurate here, because sometimes an electrolytic just needs a little reform, and isn't really bad), and all other capacitors should have absolutely no leakage. Best checked with a high voltage capacitor checker, but can be done fairly well with an ohmmeter, too, if it is a high impedance meter.
:
:T.
:
You might consider NOT plugging in a radio to see where the smoke comes from as a method of diagnosis. With old radios, it is best to assume they have multiple problems, and look for bad components before applying power.
Johnnysan-

12/30/2009 11:12:16 AMLou

::...Though transformers with 120 and 240 volt windings are readily available.
::
::Most often, if an overload condition exists, it's due to capacitors. Electrolytics should have leakage in the millions of ohms or better (the ohmmeter check can be quite inaccurate here, because sometimes an electrolytic just needs a little reform, and isn't really bad), and all other capacitors should have absolutely no leakage. Best checked with a high voltage capacitor checker, but can be done fairly well with an ohmmeter, too, if it is a high impedance meter.
::
::T.
::
:
:
:You might consider NOT plugging in a radio to see where the smoke comes from as a method of diagnosis. With old radios, it is best to assume they have multiple problems, and look for bad components before applying power.
:Johnnysan-
:
:After removing all the tubes and pilot light, there should be no load on the transformer except internal losses (a few watts). A watt meter or dim bulb tester will then indicate if the transformer is bad (before it starts smoking). If it passes, shorted filter capacitiors would be next on my list of things to check.

:

12/30/2009 11:43:13 AMLewis L

:::...Though transformers with 120 and 240 volt windings are readily available.
:::
:::Most often, if an overload condition exists, it's due to capacitors. Electrolytics should have leakage in the millions of ohms or better (the ohmmeter check can be quite inaccurate here, because sometimes an electrolytic just needs a little reform, and isn't really bad), and all other capacitors should have absolutely no leakage. Best checked with a high voltage capacitor checker, but can be done fairly well with an ohmmeter, too, if it is a high impedance meter.
:::
:::T.
:::
::
::
::You might consider NOT plugging in a radio to see where the smoke comes from as a method of diagnosis. With old radios, it is best to assume they have multiple problems, and look for bad components before applying power.
::Johnnysan-
::
::After removing all the tubes and pilot light, there should be no load on the transformer except internal losses (a few watts). A watt meter or dim bulb tester will then indicate if the transformer is bad (before it starts smoking). If it passes, shorted filter capacitiors would be next on my list of things to check.
:
::
:
Lewis

12/30/2009 9:56:25 PMHey Lewis!

I have an 89B that the transformer smokes when powered up. I pulled the rectifier tube and powered it up, NO smoke. What does that tell me?
Brett

12/31/2009 12:46:52 PMLewis L

:I have an 89B that the transformer smokes when powered up. I pulled the rectifier tube and powered it up, NO smoke. What does that tell me?
:Brett
:
It tells me that there is a short in the B+ somewhere, you should be able to find it with an Ohmmeter. Start at the rrectifier cathode, and track all the B+ until you find zero Ohms. Then, let's troubleshoot.
Lewis

12/30/2009 2:50:27 PMTroubeshooter

:You might consider NOT plugging in a radio to see where the smoke comes from as a method of diagnosis. With old radios, it is best to assume they have multiple problems, and look for bad components before applying power.
Looking for smoke is the fastest way to locate the problem. Every old set should be immediately powered up without looking at anything. When the smoke stops, you just follow the blackened tracks to find the bad part. Never change more than one burnt part at a time. Each time you fix one, power the set up again and repeat the process. Replacing several burnt parts at once may cause you to miss some pre-burnt ones that you might not find otherwise. This is a tried and true process developed over decades that will never fail to find many, many bad parts in every set you work on.

12/30/2009 3:17:11 PMBill G.

Don't write that someone may believe it.

Best Regards,

Bill Grimm

12/30/2009 10:42:50 PMTerry Decker

:
::You might consider NOT plugging in a radio to see where the smoke comes from as a method of diagnosis. With old radios, it is best to assume they have multiple problems, and look for bad components before applying power.
::Johnnysan-
:
:
:
:Looking for smoke is the fastest way to locate the problem. Every old set should be immediately powered up without looking at anything. When the smoke stops, you just follow the blackened tracks to find the bad part. Never change more than one burnt part at a time. Each time you fix one, power the set up again and repeat the process. Replacing several burnt parts at once may cause you to miss some pre-burnt ones that you might not find otherwise. This is a tried and true process developed over decades that will never fail to find many, many bad parts in every set you work on.
:
:
:

12/30/2009 11:15:31 PMAnthony Bitetto

::
:::You might consider NOT plugging in a radio to see where the smoke comes from as a method of diagnosis. With old radios, it is best to assume they have multiple problems, and look for bad components before applying power.
:::Johnnysan-
::
::
::
::Looking for smoke is the fastest way to locate the problem. Every old set should be immediately powered up without looking at anything. When the smoke stops, you just follow the blackened tracks to find the bad part. Never change more than one burnt part at a time. Each time you fix one, power the set up again and repeat the process. Replacing several burnt parts at once may cause you to miss some pre-burnt ones that you might not find otherwise. This is a tried and true process developed over decades that will never fail to find many, many bad parts in every set you work on.
::
::
::
:
:That sounds like my first marriage.

Sounds like my CURRENT marriage!
:

12/30/2009 11:17:57 PMThomas Dermody

LMAO!!

T.

12/31/2009 12:23:31 AMMarv Nuce

Terry,
And mine too!!!

marv

::
:::You might consider NOT plugging in a radio to see where the smoke comes from as a method of diagnosis. With old radios, it is best to assume they have multiple problems, and look for bad components before applying power.
:::Johnnysan-
::
::
::
::Looking for smoke is the fastest way to locate the problem. Every old set should be immediately powered up without looking at anything. When the smoke stops, you just follow the blackened tracks to find the bad part. Never change more than one burnt part at a time. Each time you fix one, power the set up again and repeat the process. Replacing several burnt parts at once may cause you to miss some pre-burnt ones that you might not find otherwise. This is a tried and true process developed over decades that will never fail to find many, many bad parts in every set you work on.
::
::
::
:
:That sounds like my first marriage.
:

12/31/2009 1:16:54 PMWarren

:Looking for smoke is the fastest way to locate the problem. Every old set should be immediately powered up without looking at anything. When the smoke stops, you just follow the blackened tracks to find the bad part. Never change more than one burnt part at a time. Each time you fix one, power the set up again and repeat the process. Replacing several burnt parts at once may cause you to miss some pre-burnt ones that you might not find otherwise. This is a tried and true process developed over decades that will never fail to find many, many bad parts in every set you work on.

The above statement does prove how radios work. It is smoke trapped inside. If you let the smoke get out, the radio won't work anymore.