Peavey VT classic 2x12 issues

[Toshiro38]

I am a guitar maker wanting to get into some amp work and my first project is to bring this Peavey back up to snuff to use as my shop amp.  Here are the problems:

After 10 or 15 minutes it starts to lose signal (volume goes down and sound gets thin) and then it goes out completely. 

The reverb does not come in unless you kick the amp and get the springs to move and then the control is not even.

I have the schematics and the users guide. Also does any one know of a demo or tutorial of a safe way to discharge the caps on this amp prior to getting in it?

Thanks for your help!

[gearhead63]

First you need to find out if it's the preamp or power amp causing the problem.
Run into another amp from the preamp out and see if it keeps working. If it does then it's a power amp issue. If it cuts out then it's in the preamp section.
Hook a preamp, mixer, what have you, into the power amp in and see if it cuts out. That will tell you where to start looking.

[phatt]

Judging by the kicking to bring reverb to life the circuitry and connections is likely in need of overhaul.
It's likely there was a ground issue anyway and while upgrading to better active devices you have made those already failing connections worse.

If hum then ground path is the most likely followed by psu problems,, my money is on ground path.
Phil.

[Roly]

a safe way to discharge the caps on this amp

Two insulated clip leads and a 100k resistor.  Clip the leads onto the resistor, then clip on the ground end, finally clip the other end to the hot terminal of the main filter cap.  Use your voltmeter to watch the voltage go down.  Once it gets to about 20V it should be safe to work on.

Note: always UNPLUG from the mains before working on any amp (don't just switch off).