Peavey Classic Chorus 212 wont switch channels

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Shawn987
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Joined: Wed Feb 27, 2019 11:05 am

Peavey Classic Chorus 212 wont switch channels

Post by Shawn987 » Wed Feb 27, 2019 11:15 am

Hi Peavey peeps. I have a couple of problems with a Classic Chorus 212 that I've recently acquired. The clean tone to it is amazing at any volume, but there is a low distortion sound in the background that gets much more prominent in the lower notes and the channel selector button does nothing at all. Makes no change in the sound. Since it won't switch to the gain channel, then the Lead Gain and Voicing sections make no difference either. The serial number is 0A-XXXXXXXX and it has "90B" in the lower right corner of the tag, so not sure if it's an '80 or '90 model. Could this be caused by capacitors, ss relay, etc? Any ideas would be greatly appreciated.

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Pappy B
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Re: Peavey Classic Chorus 212 wont switch channels

Post by Pappy B » Wed Feb 27, 2019 4:12 pm

Your noise could be one or more capacitors and/ or other components such as diodes that are leaking. First thing I would do is pull the chassis and doe a good cleaning of all jacks, pots, switches and connections using a deoxidation cleaner for electronics. Do not use WD40.

Inspect the Footswitch jack for damage or broken wires. Look at the Electrolytic Capacitors, if any have a bulged or deformed end it is most likely bad.

All of this may not find any of your problems but a good cleaning helps eliminate distractions wile trouble shooting.

Here's the schematic. I think it will be the right one.
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The more I learn the more I realize how much I don't know.

Tympin
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Re: Peavey Classic Chorus 212 wont switch channels

Post by Tympin » Sat Mar 02, 2019 3:22 pm

Hi , I have a Peavey stereo chorus 212 , 1990. Model I bought second hand . It was in really good condition to start with but I did take it apart and clean it up , because I think I’ve got ocd when it comes to things like this, anyway, I grit blasted the corner protectors and various othe metal bits, in work ,and re-sprayed them. I then pulled the original scorpion speakers and took them apart , checked the coils etc. Hoover some dust from the surrounding areas. Then I pulled the chassis and again cleaned some dust and dirt from the pcb. Now the next thing I did was to replace four of the main capacitors. I’m no electronics expert by no means , but after watching various videos on YouTube , in perticular , ( d lab) check this guy out , (to me he is the wizard of electronics and guitar amps) , I decided to have a go. So I ordered the correct capacitors from f and t in Germany and resoldered the new ones back in , checking correct polarity etc. After cleaning the pots as well with deoxit spray , I was nervous turning the amp on again . But when I did , oh my god ,what a difference In tone and sound . I can’t believe it. The stereo sound and chorus on this thing is amazing , this is a keeper that’s for Shure . I will definitely be servicing my own amps again in the future.
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Shawn2571
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Re: Peavey Classic Chorus 212 wont switch channels

Post by Shawn2571 » Fri Mar 17, 2023 7:29 pm

It's a bit different from mine, mine has the teal color on it and isn't classic just stereo chorus 212. But 2 or 3 of the knobs on it are push/pull. The first gain knob all the way to the left needs to be pulled out for my footswitch to change channels. But like i said yours may be different. Just bought mine today and had to figure it out.. lol thought the foot switch was broke at first.

RichardParker
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Re: Peavey Classic Chorus 212 wont switch channels

Post by RichardParker » Tue Jan 02, 2024 11:30 am

I know this is an old thread and most likely solved.
I stumbled on it for the switching issue.
However, as far as the distortion issue...I learned from experience,
That one or both of the speakers are the problem. They are not blown.
Try tapping or pushing the speaker cone , If it makes any noise, You have found the trouble. It may even be a good idea to service them anyway.
The foam from the magnet vent has deteriorated and found its way into the space between the voice coil and magnet.
The repair is to take out the speaker. remove tha magnet and clean out the bore in the magnet and gently wipe off the voice coil...WAllah.

My SC will use all the channels but only 2 at a time. the Manual switch must be engaged. My unit is a pull on the volume knob not a pressable swith.
I/e the bypass on the footswith does nothing.
I can solder an from what I have read it is probably one of the op amps. Could someone precisely tell me which one that is an where to source a part please.

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