Peavey Deuce VT with no output

[HNKTNK]

My Deuce stopped making any sound whatsoever when I turned it on the other day. I made sure that all cables, speakers, power tubes, and the effects loop weren't the cause.

I opened it up and started taking voltages. I'm getting super low voltages on the power supply between the stand by switch and the drivers, but the rest of the power supply looks as it should, as well as the tube socket assy. I'm only seeing 6.6vdc on R4 and both IQ1 and IQ2 are reading just about the same on the base. Like I mentioned, all other TP's on the power supply look the way they should. I'm testing with an 8 ohm load with no signal.

Any ideas on how to proceed?

[The Dude]

Your schematic link is dead. Here's another that should work.

https://www.thetubestore.com/lib/the...-Schematic.pdf

You have 6.6V on R4, so what do you have on the "input side" of the standby switch? Or, what about either side of R1?

[HNKTNK]

Crap, thanks for the proper link. I have 517v on the side coming from C6 and 6.45v on the opposite side.

[The Dude]

Is that right on the switch or before R1? If it's on the switch, either you didn't flip the standby switch, or it's bad. If you didn't mean the switch, the resistor may have gone towards open. Or connections in that area are bad. Maybe cold/cracked solder on the resistor, loose connectors, etc.

[glebert]

I fixed a friends Deuce VT that had a similar issue. IIRC at least one of the PI transistors IQ1 and IQ 2 were shot and at least one of the resistors that connect them to the high voltage IR6 or IR7 had somehow radically changed value (up to 200k or something) and it totally pulled down the supply. Maybe something to check.

[Enzo]

Oh, is the 400 ohm resistor open or not...start there.

Is the standby switch electrically sound? And the wiring to and from it?

[HNKTNK]

Thanks for the advice everyone. Yep, sure enough, R1 was the cause.