Peavey VK100 Preamp Input Issues

[donnagray]

Hello,
I'm new to the forum and have some issues. The 2 inputs on the preamp side of the amp don't produce any sound. It still works fine if I plug into the return input. All of the 7 tube/valve filaments glow and the tubes themselves get warm when it's turned on. When I plug into either of the 2 preamp inputs, they don't react at all, and it hums kinda loud no matter if anything is plugged in or not. I've only just started to research how amps and tubes actually work, here in the last day. I'm sure I need to send it to a pro. However, if there's anything I can try before that, I'd like to give it a shot.

Any ideas? Thanks in advance!

[j0nsnell]

Assuming you are competant with dangerous, high voltages, check R203 fot the B+ supply to the preamp valves.
No B+ means no sound.

[65 SG]

Try this - turn the Reverb all the way up and bump the amp hard. Do you hear the crashing sound of the reverb? If YES, it could be a B+ issue, as j0nsell suggests.

If NO, first thing I'd check is Q101, which mutes the preamp output signal during channel switching (for noiseless switching and so the reverb doesn't respond to the glitch). When Q101 fails ON, mute is permanent. If you don't use reverb or don't switch channels (or don't mind the pop when switching), you can remove Q101, and fly without it until you get it fixed.

If you're new to this, you definitely need to read all the warnings and disclaimers about high voltage, keep one hand in your pocket, etc. Good luck