[Heathkit] O-12 power transformer

[Kevin Ward]

Richard -

Once upon a time someone gave me a piece of equipment (Knightkit I 
believe) which he said "just quit operating."  The filaments powered up 
but as the saying goes, "the lights were on but nobody was home."  My 
friend said there was no flash, bang, or smoke - - it just quit!

A quick check with the VOM confirmed an open winding in the power 
transformer.  I made a quick sketch with notes on where all the wires 
went and dug out the transformer.  I pulled off the end bells and had a 
look.  The winding had parted, right at the end of the last turn of the 
winding.

I had to unwind a single turn to get a free end I could work with, but I 
was able to restore operation.  I replaced both electrolytics because 
one had a bulge, even though both tested OK, and never had another 
problem with that unit.  I recommend you replace those caps.

If you're going to replace the transformer anyway, you have nothing to 
lose by pulling it and having a look.  Just don't forget to document 
your work as you go.  Especially if you don't have the manual and 
schematic.

Kevin  N2IE