Peavey Classic VTX

[stereomonostereo]

I'm working on a Peavey Classic VTX, SS/Tube hybrid. When playing a guitar though it, there was very little signal unless you really layed into it. I tracked the problem down to the bias/output section. Where the Q6 and Q7 5884 chips should be reading +560, i'm reading 110v and 70v. CR32 and CR40 are reading 0.60v.

My tube plate voltages seem correct, but due to whatever the problem is the tubes aren't being biased correctly. I'm not too familiar with the bias circuit they're using.

Can anyone steer me in the right direction?

[52 Bill]

I don't know, but should the +560 be +0.56 volts? I don't see where +560 volts would come from.

[stereomonostereo]

I was kinda wondering the same thing.

Anyhow, i found the CR37 diode was shorted and replaced that, and it seems to be working. My voltages are still reading the same but the tube bias is there now.

[teemuk]

Error in schematic. It's supposed to be +.560V

They got it right at the other side of the push-pull, and it's more or less a symmetric circuit so...