Toroidal Transformer Repair Question

[KyferEz]

Basically I have this transformer with burned wires in the secondary. The insulation was somehow damaged and quite a bit of the enamel is burned off of about 8" of wire. The wire itself seems ok. I don't really want to re-wrap the whole transformer. Is it Ok to uncoil the wire to a little past the burned area, re-coat it and go on? Or is that asking for trouble?

If its Ok to just fix the burned area, then what is good to use on the wire? I have some Plastidip rubber coating spray paint, would that do? Or should I pick up some high temp enamal paint?

Thanks!

 

[Perry Babin]

It would be better to re-wind it but if that's out of the question...

Heatshrink tubing will work. You can also wrap it in Kapton tape. The tape will be thinner and may allow you to resolder the wire normally. With heatshrink tubing, the wire may come up a bit short.

If you don't have the tape or heatshrink tubing, you can saturate paper with epoxy and lay it down between the windings. This will be permanent and won't be easy to undo if you need to unwrap the windings again. Also, do NOT breath the fumes if you accidentally get epoxy on part of the wire that needs to be soldered. The fumes are EXTREMELY unpleasant.

Wires burn like this when one winding shorts to another winding.

 

[KyferEz]

So I used the heat shrink method since I haven't gotten the kapton tape in yet and have, as you expected, come up short. Do I extend the wire or let it be a turn short?

 

[Perry Babin]

Extend it. Wrap part of the extension around the original wire to provide a good mechanical connection as well as a good electrical connection.