Found a Peavey, it's making a weird noise...

JamesSGBrown

Hey all!
Found a Peavey Studio Pro 112. Plugged it in and it sounds like this 

Why? It's solid state. I don't think it's the speaker...but you guys know better than me. I have a soldering iron at the ready!

DJH83004

First thing to do is try and isolate the fault to either the preamp stage or power amp stage. I think the Prostudio has a preamp-out socket and a power amp-in socket, so plug your guitar into the 'power amp-in' socket, to see if the distortion is still present, it will obviously be a lot quieter than normal, but should be loud enogh to carry out the test. Similarly you can plug a lead into the preamp-out socket and into another amp. 

ICBM

Congratulations, you have a very rare amp!

An old Peavey solid-state amp with a fault .

Depending on the age of it, it may well have socketed ICs throughout - if so, the first thing to do after what DJH said and especially if it turns out to be in the preamp, is to give all of them a squirt of contact cleaner and make sure they’re pushed tightly into the sockets. They can sometimes work loose or get a spot of corrosion in one of the pin connections. Don’t take them out, just wiggle them a bit while pushing down. 

JamesSGBrown

It doesn't have the aformentioned ins and outs. It's got an efx loop, plugged in to the send and return for the hell of it and the distortion is still present...

ICBM

Do you mean you plugged the guitar into the return and the distortion was still present? If so you know the problem is after there, or common to the whole amp - ie not in the preamp.

At a guess, one possibity from the sound is that one half of the split-rail power supply is down, which would affect the whole amp. If so it should be relatively easy to fix and may be as simple as a broken solder joint.

DJH83004

Working on ICs very plausible theory that one of the +/-15volt supply rails is down, they are derived from 5watt dropper resistors and 15v zeners, so a very logical place to start. Also whilst you are in that area check the +/- supply rails that drive the output section of the amp.