Peavey Butcher dead

[swapjockey]

First hello.I just signed up hoping to find a schematic which I have.While I'm on thought Id post a question.I've repaired tvs and such for about twelve years.This is only about second amp I've ever looked at.Hadn't gotten schematic yet so just did some routine checks.Power supply seems fine.Have 468 volts going to second transformer.By the way I have a old suitcase type tube tester and all tubes tested in good range.All filaments light up bright, when in amp.Symptom is zero output on speaker, no crackles, pops, hum, nothing.An time saving place to start would be grateful.Thanks.

[Jerry]

Try to isolate the problem. That amp has effect loop jacks. Put a signal into the preamp and see if you get signal at the preamp send jack. Input a signal into the power amp in jack and see if you get any output. You'll need to have the tubes in and the head hooked up to a speaker.

[Enzo]

Pretend it was a TV with no sound, what would you do?

First, I'd test the speakers. Touch a 9v battery to their terminals briefly. A working speaker will make a pop or thump noise with each touch. Don't leave it there. Or use an ohm meter for continuity, but disconnect them from the circuit if using a meter, the output transformer will mask an open speaker. And just because the speakers themselves work, doesn't mean the little speaker cable running up to the amp chassis is OK. test it too. Do both this way - pull the plug out of the amp, then touch the 9v battery to the tip and shaft og the plug. If the speakers AND wiring are OK, the speakers will pop or thump.

I am betting it is this: open resistor in the B+ (high voltage) line between plates and screens on the power tubes.

+468v sounds about right for the plate supplies, maybe a little low, but plenty to make it quite loud. That goes to the output transformer center tap, and through that winding to pins 3 of each power tube. In the power supply there is a large 10 watt resistor, 400 ohms or maybe 390 in some amps. The standby switch is wired in series with this resistor, the switch interrupting the B+ path to the rest of the circuitry. With standby switch on, there should now be B+ voltage on the screens of the power tubes at pins 4. It will be some 10 volts lower than the plates. That resistor likes to open more often than other failures. If tehre is 468v on the plates but nothing on teh screens, it is likely the resistor.

Um, you do know that BOTH power and standby switches must be in the ON position for the amp to run?

[Gtr_tech]

First hello.I just signed up hoping to find a schematic which I have.While I'm on thought Id post a question.I've repaired tvs and such for about twelve years.This is only about second amp I've ever looked at.Hadn't gotten schematic yet so just did some routine checks.Power supply seems fine.Have 468 volts going to second transformer.By the way I have a old suitcase type tube tester and all tubes tested in good range.All filaments light up bright, when in amp.Symptom is zero output on speaker, no crackles, pops, hum, nothing.An time saving place to start would be grateful.Thanks.

http://www.schematicheaven.com/newam...ey_butcher.pdf