I don't know how your question ended up in "Computers", but I'll try to help you anyway...
I found a
schematic/manual for your PEAVEY, but I think it's a just
partial schematic because no power supply is shown? A link is provided below...
The manual mentions your "Clipping Indicator" but mentions only
on IF DISTORTION is present.
See page 21.
That LED circuit samples audio BEFORE and AFTER your "3 band equalizer". That equalizer is only shown as a "block" with no other specifications other than
"CHANNEL 19 - 20".
*See page 29.
In your case it appears that your CLIPPER is sensing a signal overloading condition OR that IC may be defective? And because it's only shown as a block, there may be more than one IC or many other components involved in that section?
In fact the fault may be well before your CLIPPER sensing circuit! In example a bad or leaky CAPACITOR in your power supply MAY be injecting AC into your Mixer? I've just added a SECOND link below showing bad and good capacitors.
It's difficult to say without a voltage chart or the IC DEVICE numbers known...A full schematic would have helped us both more... I hope this was of some help to you!
Armed with this manual, your broken PEAVEY
and the schematic I think a good tech should be able to sniff out the problem... Look for burnt or discolored items FIRST!
Anthony
https://media.americanmusical.com/ItemFiles/Manual/PeaveyXR1212MixerManual.pdf
Good Bad Ugly Capacitors EMBEDONIX