Ampeg VT40 weird standby switch

[jewishjay]

I replaced the filter caps in an old Ampeg VT40. Here's a schematic before and after. The switch apparently lifts the ground on the bridge and the lamp. But I must have done something wrong, because now it hums really bad. All the voltages are the same as before, but no music comes out, and it buzzes when you flip the standby switch. It's (obviously) silent in standby. Did I create a ground loop somewhere with this goofy standby switch? Does anyone ever mod the standby to be more traditional? Interrupt B+ ?

[sluckey]

The plate and screen caps were originally connected to the negative side of the bridge, but your modified schematic now has them connected directly to ground. I would start by making that right. This circuit would be easy to bugger up in other ways too.

[PRR]

It worked for Ampeg. You did something different. Don't.

[jewishjay]

Working again, thank you both. I moved the ground for filter sections 1 and 2 back to the neg side of the bridge, and the amp now operates.

However, its not very loud. You have to crank the preamp volume almost fully and the master past half way to get any sound at all. Same on both channels, so I think something's wrong in the phase inverter or power amp? I didn't make any other changes. Voltages all look right, so maybe I'm loosing signal somewhere?

[PRR]

A half-healthy VT-40 will annoy the neighbor at the end of my block. That's about a mile.

Mine did not have a Master? There were several variants. This one below has the awful "Distortion" but no Master.(*) IF this is your plan, the numbers in boxes are signal AC Volts for the specified input and some nominal knob setting.

(*)(It also has the correction to the mis-drawn Distortion circuit which I have never seen elsewhere... I offered it to the original Schematic Heaven just before they went down.)

[jewishjay]

SOLVED! It was a simple loose or dirty tube socket. The compactron 3 triode tube. Everything now works as it should. Its not likely to become my favorite amp, but with your help it's healthy again.

Thanks again for your insight and patience!