Hey there, I have a Crest Pro-Lite 7.5 Amplifier with an existing channel problem on my bench that was given to me by a friend. Input B and Output B appear to work correctly. Input A has an issue - when given the same signal on both channels, Input A appears to trigger ACL LED to turn on about 12-13db below Channel B. In other words, Channel A appears to clip at a much lower volume level than Channel B.
When I have a speaker plugged in I'm getting almost zero volume out of Channel A, maybe a very faint sound. Even when the clip indicator on the channel is close to triggering. I've tried calling the Peavy service center today but haven't been able to get through. Techs near me listed as Peavey service centers don't want to work on this amplifier, and understandably so because it has a lot of surface-mount parts.
I've cleaned out the amplifier of dust quite thoroughly with compressed air, cleaned connectors on the main board with rubbing alcohol and reseated them. Visual inspection shows nothing really out of the ordinary. I haven't got access to the underside of the main board as it has these plastic clips holding it in and I didn't want to break them trying to get in. Might be some dust still hiding under there.
I'm quite handy with electronics as a hobbyist. I've built dozens of eurorack modules and done a lot of soldering and desoldering, but I'm not great with understanding and diagnosing circuits. I can use a multimeter and follow directions. So does anyone have any information that could help me tackle this? It's weird that there appears to be a problem that is affecting both the input section and the output section of the same channel.
I could try swapping the connectors for the channel gain potentiometers and if the problem moves with them that would be the culprit. Seems like a long shot if the output section is not working right either though. Anyway, thanks for listening to my story. I'm posting here to hopefully find a solution and help others who might have similar issues.
-Cheers, Chris, Glitter Skulls, Ithaca Underground & Microtones Collective, Ithaca, NY
Crest Pro-Lite 7.5 Bad Channel Problem - early clipping indicated and very low output
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Re: Crest Pro-Lite 7.5 Bad Channel Problem - early clipping indicated and very low output
I’ve had the exact same problem. I wonder what it could be?? Has anyone reached to you?
Re: Crest Pro-Lite 7.5 Bad Channel Problem - early clipping indicated and very low output
Without picture it is hard to tell, but some plastic clips are snap-in, and you can squeeze them to fit through the board holes again.glitterskulls wrote: ↑Thu Mar 09, 2023 10:07 amI've cleaned out the amplifier of dust quite thoroughly with compressed air, cleaned connectors on the main board with rubbing alcohol and reseated them. Visual inspection shows nothing really out of the ordinary. I haven't got access to the underside of the main board as it has these plastic clips holding it in and I didn't want to break them trying to get in. Might be some dust still hiding under there.
The symptom may fit with high frequency oscillation which would make circuit analysis non-trivial.
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Re: Crest Pro-Lite 7.5 Bad Channel Problem - early clipping indicated and very low output
I was able to reach someone at the Peavey Service center who gave me instructions on how to send the amp in. I didnt bother to describe the problem since full diagnosis over the phone is unlikely, and they seemed very busy. But they were nice and confirmed they will work on the pro lites which is good. I have one local electronic tech genius who's offered to take a look. If that doesnt go well I will send it to Peavey.
Re: Crest Pro-Lite 7.5 Bad Channel Problem - early clipping indicated and very low output
Has Peavey reached out to you on what the issue is? Wasn't sure if they got to it yet.
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Re: Crest Pro-Lite 7.5 Bad Channel Problem - early clipping indicated and very low output
I've been a bit busy so just got around to shipping the thing to Peavey. They got back to me within 1 week after receiving the unit. Invoice says they fixed Channel A, Replaced a 6.2v Diode, Touched up solder and lubed pots all for $90 plus shipping back to me in NY around $20.