Ampeg V4 distortion model

[g1]

You may be able to see arcing with the lights off. Like I said previously, the board mounted tube sockets are notorious for bad solder. Hate to say it but on my V4's I just bit the bullet and completely resoldered all boards.

[methodofcontrol]

all that noise wasn't a bad solder joint, but a bad connection in the tube socket. i re-tensioned the socket and lubed up the tube pins w/ contact cleaner, and all is well now.
the last problem i have is a squeal-like oscilation when the volume is way up and the treble is past noon. i'm pretty sure it's because my new 6an8 is microphonic. so, i'm not sweating it just yet. we'll see what happens when i get non-microphonic PI in there.
thanks for all of the help! i may be back to troubleshoot the squeal if it's not the tube, otherwise the amp is back in the land of the living. thanks again.

[g1]

Was looking at the schem. again and voltages shown for V201B don't add up either (screen voltage higher than plate, less current through cathode than plate). Your voltages make more sense.
As far as the voltages shown, this is one of the worst schematics I've seen. I can't believe corrections were not made when amp was current model and warranty work was being done.

[methodofcontrol]

thanks! good to know.