I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red
case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I
started testing it and it was welding fine but suddenly the box started buzzing
much louder than before and it won't weld worth beans any more. I haven't taken
it apart yet. I figure something could be shorted to ground (although the 30A
mains fuse didn't blow) or whatever holds the transformer laminations together
might have cracked.

Anyone got any bright ideas what to look for? I'd like to salvage this one.

Grant Erwin
Kirkland, Washington