[Amps] SB-220 and Copious Amounts of Smoke...

[Jeff Carter]

Hi all,

The SB-220 I've been rebuilding has developed a problem.

I put brand new tubes in it, and when I fired it up, within ten
minutes the filament transformer began *smoking*.

I thought maybe some of the wiring or components were burned, but an
inspection didn't reveal any.  I removed the side panel and put power
back on the amp, and sure enough, the smoke is coming from the
transformer itself.

I can't find a problem in the wiring.  Of course, it doesn't do this
this with the tubes removed, it'll merrily sit there all day with no
tubes.

Ideas?  What have I done wrong?

Thanks,
Jeff/KD4RBG