Old Tranny Potting Material

[audiopro]

I need to remove a transformer from it's cover. The tranny is held in with a black potting material. Does anybody know what this stuff is.
The transformer in question is the power tranny from a Heathkit W-4M amplifier. Pretty old.

 

[Eli Duttman]

Somebody with exact knowledge will have to speak up, but what you describe seems to be the stuff I know was used in the H/K Cit. 2 trafos. The Cit 2. trafos are potted in mixture of tar and ground slate.

 

[serengetiplains]

... tar and ground slate ...

Probably just the answer you were looking for? Nothing like a little tar to make one's day!

 

[SY]

With heat, a lot of cursing, and mess, you can get the transformer out of the goop. But don't use any open flame and watch the temperature. A kitchen oven (if you and anyone you share it with are tolerant) works very well. Try starting at 250F, then increment upward in 25 degree steps until you get the material to melt. Allow LOTS of time for the entire tranny to heat up- there's a pile of heat capacity in iron and copper!- and LOTS of time to cool down before touching it with bare hands.

 

[audiopro]

Thanks guys,
I know this is going to be a gooey mess. I was planning on using an old BBQ one last time to heat this up. That way it won't stink up the house. I'm not worried about the enclosure I'm getting them painted anyway. Just was worried about the fumes.

Thanks

 

[Eli Duttman]

Just was worried about the fumes.

A charcoal respirator might be a good idea. Keep a fire extinguisher handy; just in case things go wrong.

Good luck.

 

[audiopro]

Good idea, the extinguisher I've got, the filter mask I'll pick up.

Thanks