UTC transformer repair

This is a quick and simple page to show what can be done to attempt a repair to one of these valuable UTC transformers.

I had a UTC A-11 transformer that was showing a bizarre combination of shorts and oddball resistances across the various connections, including shorts between the primary and secondary coils. I figured someone had fried this poor thing with an excessive input voltage or something. As with all things broken, I decided to see what was inside. I found that to gain entry into the transformer, all one needs to do is drill off the top part of the holes where the machine screws go into the transformer for mounting. Then one can gently pull the terminal plate up to inspect the inside.

In this case, I was thrilled to find that one of the wires had been laying against another terminal on the under side of the terminal plate. When it was soldered (or desoldered) it got hot enough to melt through the insulation and short out. A little repositioning of the wires and it is as good as new. (well, except cosmetically)

I then Gorilla glued the terminal plate back in place with very small dabs of glue and rejoiced in the resurrection of this valuable transformer.

Maybe next time I won't be so lucky and I'll explore de-potting the trafo itself. It appears to be potted in wax.

At the back you can see the repositioned brown wire after I pulled it free of where it was melted and shorted.