1984 Peavey KB100 Amp -Only HUM

[JayZ]

Thanks everyone! I took it to "Herb" in Hamilton. He's retired now but still does the odd amp repair. He's always been successful at fixing my gear in the past! When it's working again I'll post what Herb found as the problem(s).

 

[JayZ]

You are all probably going to laugh but it turns out it was a bad ground on a power supply 2200/50 cap (CR59 on the 1984 schematic). I only did a visual exam of the PCB for bad connections b/c I was afraid to do use the "eraser tab" method when powered up b/c of the "hum".
Anyway - replaced the dual diode and all is well! Thanks again for your advice!