peavey renown 400 reverb problem

[sam0812]

HI all this is my first post so please be kind.My peavey renown 400 "solo series" 2x12 210watt combo has developed a reverb problem.Everything on the amp works fine except the MASTER REVERB .Turn the knob a quarter and it starts to feed back,turn half way and it makes horrible noises.Ive tried unplugging the reverb tank,another tank of the same specs and so forth but I suspect the problem is in the circuit board.Is this a common problem? Any help greatly appreciated SCOTT

[Enzo]

Common problem? No.

Let me understand, with the reverb pan cables completely unplugged, the amp feeds back when the reverb control is turned up? Disconnect the cables at the amp chassis end, not just at the pan itself. Are we talking actual feedback, like screeching tone? or is it more of a low foghorn sound? Or does unplugging the pan make it stop?

[sam0812]

Ok I unplugged reverb from chassis,turned every knob to zero.When I turn up reverb knob between 4 and 5 the amp 'bumps' on and makes a very high pitch noise that gets progressively louder as you turn the reverb up. If I plug the pan back in it feedsback at about 2 to 3 and goes bananas at 4 to 5 Amp seems to be running at full power like the reverb is master volume. Remember all other knobs on zero. Thanks for the reply SCOTT

[Enzo]

Are you prepared to solder parts on and off the circuit board? If not, take it to a service tech.

Otherwise, get the schematic from PV and start in. Try a swap of U7. Nearby is R61 and C34, make sure that 68k resistor is not open.

I think the ICs are in sockets anyway, so pull U7 - the reverb IC - from its socket and power up. Silent now?

[weirdjimmy]

I feel your pain. Got the same problem with my Renown 400

[sam0812]

Ive swapped the IC,[ actually all seven as they were only a buck each,]seems to have fixed part of the problem. Now the reverb knob just creates a 'microphonic' feedback which is directly related to how far you turn the reverb up,starts about 2 to 3 on the dial. There is no' thump' at 4 to 5 or any crazy noises like before. Now that I know how to pull it all apart I might take the circuit board to a tech and let them have a look.Thanks for all your help its been great SCOTT

[Enzo]

Please don't do that. What would a tech do with a board out of an amp? Unless he happened to have a Renown 400 in his shop he could stick your board in, he would have no way to power it up. And when a circuit is not operating, there is no way to check its operating parameters. The last thing a repair shop wants is an amp all torn apart. (We call them "kits.") it will be more clumsy to handle, it will require finding some place to set it. Believe me, tearing the amp apart before taking it in doesn't "help," nor does it "save time." And it won;t save you any money. In fact. even if he COULD power it up somehow, he can't test it in YOUR amplifier. The other parts in the chassis could be involved in various problems. A whole amp, I can sit on the floor, I can stick it in a corner.


How does it work now with a good reverb pan connected?

[sam0812]

Sorry enzo.I meant take the whole chassis to a tech he would only have to plug it into a speaker. Would just save lugging the whole heavy thing around. anyhow Ill ask before I take it. As far as the new ICs go its much better now, it just feeds back slightly at 2to3 on reverb knob and gets worse as you turn reverb up.Before it was the same but when you got to about 4 it would go full volume insane racket.Thats gone now.