Peavey Ultra Plus 410 help needed

[Speaker Junkie]

Hello! I am new here and looking for some help. I have a Peavey Ultra Plus 60 watt / 410 model. The clean channel seems to be muted. The crunch and ultra channel still work fine. I’ve tried swapping around preamp tubes. Still nothing. Has anyone else experienced this? All input and help will be appreciate. Thank you!

[Delta362]

Since it's just the clean channel, that leaves only a handful of components to impact it: high/mid/low/clean pre pots, plus relay K1A contacts, and some caps. I've uploaded what I think is the correct schematic. The components I mentioned are all on page 1 near the bottom left.

[Speaker Junkie]

I will take a look. Thanks!

[Speaker Junkie]

All the caps turned out to be fine. Same with the pots. Is there something that mutes the clean channel? Crunch and Ultra channels are fine. What does K1 do for the clean channel?

[g1]

K1(A) is what engages either channel 1 or ch.2/3. Are you able to read the schematic?

[Speaker Junkie]

Thanks for your reply! Okay. Since K1(A) engages either channel 1 or ch 2/3, and, channels 2 and 3 are fine, is it safe to assume that K1(A) is working? I’m trying to find the source of what is causing channel 1 to be mute.

[Jazz P Bass]

Do you have the footswitch?

[Speaker Junkie]

Yes. I do. That is how I am able to play the crunch channel. Thanks!

[Delta362]

The normally closed contacts are for the crunch channel. K1 energizes when you go to the clean channel. I suspect that the relay contact isn't switching fully. You can check for continuity across the relay when you engage the clean channel. You can do this test while on standby. You may need to replace the K1 relay.

[Speaker Junkie]

Thanks a ton! Ordering replacements now.

[The Dude]

Why not check the relay first? It's simple enough to do.

[Speaker Junkie]

Because it can’t be done unless the board is pulled

[g1]

Well, you're going to have to pull the board to replace it anyway.
I understand it's quite a pain and (if cheap enough) you might as well have it on hand in case it measures bad and needs replacement. While you have the board pulled just make sure you have a real good look at the solder connections and other components in that section of the circuit mentioned in post #2. Hopefully you only have to pull the board once.

[Enzo]

Of course any component can go bad, but in the last 30 some years as Peavey authorized repair shop I can count on the fingers of one had how many of those small relays I have had to replace,.

You want to check K1a? When it is set for clean, measure RESISTANCE from one side (C11, C12, VR5, VR7) to the other at R8. You need not be right on the relay itself, just go to whatever it connects to. Those parts are identified on the layout and are accessible without disassembly.


Remember it is all about the circuit, not the parts. Just because a resistor measures right doesn't mean its circuit path to the next part is intact. Apply a signal and see if it is present on either end of C5 then R8

[Speaker Junkie]

Thanks a ton, Enzo!