Peavey Artist 240 Help Please

[ElPedro]

So a guy brought me his peavey artist 240 to fix. Said he's not getting any sound out of it.

This amp is a discreet preamp with 6l6 power section.

I have replaced all of the big power filter caps and other larger electrolytics. Voltages look good at the tubes, running around 460 or so.

Here's what's happening- when I take the amp off standby I can get max volume for a couple of seconds. Then volume goes very faint, but steady. When I take the amp off standby, I get a discharge of volume from nearly full volume down to zero.

Any thoughts?

[Paul1453]

Maybe a test to isolate the problem?

If you could disconnect the preamp section, input say a test tone into your power amp, and see if you get the same symptom.

If the power amp keeps outputting a good test tone, for a reasonably long test period.
Then you could be pretty sure you have an issue in the preamp circuit.

Only other idea I had was that the PT is weak and going bad.
If you can isolate this to the preamp, that would be a good thing.