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Peavey Classic 120/120 dual mono
Hey guys. Figured I'd use the forum to troubleshoot this amp with you guys. Peavey tech support is down so any advise, tips or tricks are much appreciated.
Little back story. I purchased this amp from GC about 6 months ago. When it arrived it was in severely damaged condition wasn't packaged well. I returned it to my local GC and the store manager was fine with giving me a full refund including shipping charges. I asked what he would do with the amp and he said "dumpster". We settled on a salvage price and I left the store with the broken amp.
One of the output transformers had broken the welds on the mounting plate, few broken pots on the front panel and a well dented enclosure. Couple tack welds, replaced broken pots and knocked the tin back into shape. I completely disassembled the amp checking all the components for obvious damage and reassembled the amp checking the wiring with the schematic. Success! Or so I thought. The amp fired up and was working fantastic.
This week I got a hold of a multi effects pedals with stereo output and couldn't wait to try the 120/120 in stereo or dual mode. Hooked everything up. Threw the switches in they're appropriate positions turned it on both channels 1&2 seemed to go full output with trumpet like tone Loud AF. I'm trying to describe the tone of the sound. It was freight-train-like. The thunderous output would be turned off by putting either channel in standby. The problem persistent even with known good tubes. Mono operation seems to work %100. The full output feedback sound only starts off standby when a signal or chassis vibration is given and both channels one and two are on. In stereo mode both channels work fine if only one is taken off standby at a time. Soon after I take both off standby it goes into feed back and not immediately, sometimes I can get both to output at low level for a short time then feedback again. If I remove the preamp tubes from either channel I can take both off standby without the full output feed back and of course only one channel will output that still has the tubes in it.
Link to schematic:
120/120 schematic
Peavey Classic 120/120 dual mono
Hey guys. Figured I'd use the forum to troubleshoot this amp with you guys. Peavey tech support is down so any advise, tips or tricks are much appreciated.
Little back story. I purchased this amp from GC about 6 months ago. When it arrived it was in severely damaged condition wasn't packaged well. I returned it to my local GC and the store manager was fine with giving me a full refund including shipping charges. I asked what he would do with the amp and he said "dumpster". We settled on a salvage price and I left the store with the broken amp.
One of the output transformers had broken the welds on the mounting plate, few broken pots on the front panel and a well dented enclosure. Couple tack welds, replaced broken pots and knocked the tin back into shape. I completely disassembled the amp checking all the components for obvious damage and reassembled the amp checking the wiring with the schematic. Success! Or so I thought. The amp fired up and was working fantastic.
This week I got a hold of a multi effects pedals with stereo output and couldn't wait to try the 120/120 in stereo or dual mode. Hooked everything up. Threw the switches in they're appropriate positions turned it on both channels 1&2 seemed to go full output with trumpet like tone Loud AF. I'm trying to describe the tone of the sound. It was freight-train-like. The thunderous output would be turned off by putting either channel in standby. The problem persistent even with known good tubes. Mono operation seems to work %100. The full output feedback sound only starts off standby when a signal or chassis vibration is given and both channels one and two are on. In stereo mode both channels work fine if only one is taken off standby at a time. Soon after I take both off standby it goes into feed back and not immediately, sometimes I can get both to output at low level for a short time then feedback again. If I remove the preamp tubes from either channel I can take both off standby without the full output feed back and of course only one channel will output that still has the tubes in it.
Link to schematic:
120/120 schematic
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