Hi;

I was cleaning the terminals up on some old UTC LS transformers and
noticed some hard black/brown stuff around the terminals. My first thought
was that it was old flux or maybe paint(like manufacturers sometimes
put on terminals after they are wired in a chassis). After heating the
terminals, I noticed that it smelled like rubber. I suceeded at
cleaning most of if off, however, when I heated the terminals to melt
the solder, more kept comming out of the terminals(the terminals are
hollow with the coil wires comming up through). So I'm assuming that
this is potting compound "wicking" up through the terminals.

I've looked at many UTC transformers(with the same hollow fork
terminals) and notice this on their terminals also.

My question is can this contaminate the connections of the internal
wires where they are soldered up through the terminals? I checked them
with my meter and everything seems fine.

Thanks!