The trans on a 1934 Wards Airline overheated and brown waxy stuff came out. I disassembled the trans to discover a dark goo on the coverings of the windings accompanied by a bad burnt smell. Is this substance PCB? What are my risks if so? Any light shed will help.

Thanks - Barry

Barry
PCB’s are found in oil filled transformers and capacitors. Most old radios did not use a sealed oil filled transformer. I would not worry as it is just the insulating material melting , it was usually a form of tar. I would be more concerned about finding the cause of the failure before installing a new transformer.

Dave

Thanks Dave,

I have checked out the other components in the radio and everything seems OK. Radio works well even with overheating transformer, but someone has been into the power supply wiring before me - I think it is a strange negative power supply setup as one of the electrolytics is not grounded (it is possible it is wired wrong - but nothing else overheats). I did get some WD-40 on the side of the transformer and it quickly disappeared into the laminates, I wonder if this broke down the insulation around the windings. I am looking for a replacment but cannot yet determine the rating on the original one (high voltage is currently around +160v - any ideas on that?

Barry
:
s are found in oil filled transformers and capacitors. Most old radios did not use a sealed oil filled transformer. I would not worry as it is just the insulating material melting , it was usually a form of tar. I would be more concerned about finding the cause of the failure before installing a new transformer.

: Dave

Hi,
Actually PCBs were not developed until just prior to WWII. Most of the oil one might encounter from handling vintage caps is primarily Castor oil.

In the power transformers in the old radios, there was no cooling oil- The primary reason that one might encounter an oil imersed transformer (usually "pole pigs".)

It is possible that the tar (Refinery residue for an in accurate description of the very long chain hydrocarbons that made up/make up tar). There may have been an impurity of a non-volatile compund that just separated out of the tar, but this is not very likely.

As far as what caused the meltdown of the transformer tar, replace the filter caps first. Those dry out and short out. If there is any liquid in them, it is not oil.

The transformer "B" is usually around 500 volts with a center tap. If you have the model number there might be schematic for it in the Rider manual section of this site- Check the Montgomery Ward Airline models first. The chassis was made by "Wells Gardner".

: Thanks Dave,

: I have checked out the other components in the radio and everything seems OK. Radio works well even with overheating transformer, but someone has been into the power supply wiring before me - I think it is a strange negative power supply setup as one of the electrolytics is not grounded (it is possible it is wired wrong - but nothing else overheats). I did get some WD-40 on the side of the transformer and it quickly disappeared into the laminates, I wonder if this broke down the insulation around the windings. I am looking for a replacment but cannot yet determine the rating on the original one (high voltage is currently around +160v - any ideas on that?

: Barry
: :
: s are found in oil filled transformers and capacitors. Most old radios did not use a sealed oil filled transformer. I would not worry as it is just the insulating material melting , it was usually a form of tar. I would be more concerned about finding the cause of the failure before installing a new transformer.

: : Dave