volume fading out, help...

[HTH]

ok, got my mates 1959-model Marshall here (basically the JCM800 variant of the plexi) and the volume fades to almost nothing after around ten minutes of playing then ramps up again within a minute if you stop playing.

One of the main filter caps is bulging with some white spots round it and the others have smaller budges. Because the volume fades down then back up I'm thinking filter caps automatically.

I've changed the valves and the amp still displays the same symptoms.

Anyone?

[sportster4eva]

Definitely change the PS caps, bulging is not a good thing. The white stuff is the electrolyte oozing out, a sure sign of impending doom...lol!

[HTH]

seems to make sense that 'on their last legs' caps would be to blame - always nice to throw things onto the forum here and get opinions from more experienced amp techs (not that I consder myself an amp tech).