I have a Henry SS750 solid state amp. It has 8 2sc2879's (four push-pull
circuits on individual boards). It operates at 14v.
There's a decoupling circuit on the 14v lines going to each board: the cold end
of the output transformer windings is bypassed by a 0.33 uf cap, followed by
some ferrite beads, and finally a 100 uf 25v electrolytic.
My problem is the 100 uf electrolytics: I keep blowing them. I have replaced
them with 50v parts, I have tried 105 c rated parts, and I have bypassed them
with 0.1 uf discs (on the theory that RF is heating them up). They keep
blowing. There's a bang like a firecracker, a little smoke, and part of the
innards get blown out of the vent hole (on caps without vents, the whole end
gets blown out).
This happens when ragchewing (CW) on 15 or 10 meters. It has never happened on
20 or below. The amp is not especially hot when it happens. I am running about
550w output with about 70w of drive. Interestingly, it doesn't appear to affect
the functioning of the amp (although I always shut it down).
My questions are:
1) What's blowing the capacitors?
2) What is their function? 100 uf is a lot of capacity if you are bypassing