ksdaddy Posted January 24, 2014 Share Posted January 24, 2014 Today I picked up an '86 Peavey Bandit 65. Typical cold storage issues, scratchy pots, etc. I can NOT get the reverb to work. I don't have a foot switch for it so I took a stereo jack and grounded the ring so it will play on the clean channel (if there is no foot switch plugged in, it defaults to the overdrive channel). I left the tip ungrounded so the reverb should work. According to the schematic, that's all the foot switch does. I checked all cables, connections. ohmmetered the cables, etc. I even swapped the tank with a known good tank (from my Peavey Classic VTX, same exact Accutronics part number) with the same (no) results. I'm getting about 14.1 volts on the input side (reverb drive). If I tap the springs the crash comes through the amp as you'd expect. There are 4 op amp chips in this amp, all RC4558P. I swapped them out with each other, no change at all. If the reverb sprang to life (no pun intended) I would have known it was a bad chip. I don't know what to look for next. I'm not a tech so I'm limited to simple stuff, tapping and hoping to find a bad solder joint, etc. I'm quite stupid actually. I have the schematic but I can't follow any of those chicken tracks. oh, I can find my way around it, but I can't intuitively trace my way back from the tank drive stage and have a clue as to what might be causing the problem. Any takers? Link to comment Share on other sites More sharing options...
surfpup Posted January 24, 2014 Share Posted January 24, 2014 Toughie. Since the springs sproing when tapped it sounds like the "return" part of the circuit is fine and the problem is in the "send" part of the circuit. Is there a send jack/cable? Link to comment Share on other sites More sharing options...
ksdaddy Posted January 24, 2014 Author Share Posted January 24, 2014 Yep and I checked them all out, no problem. Both using an ohmmeter and also checking the voltage that's supposed to be being fed to the tank. Schematic says 15, I'm getting 14.1. Close enough. Next step is to pull the circuit board out and hope and pray to find a bad solder joint. Well actually, in the interest of due diligence I will borrow the cables from one of the other Peaveys and try them. Link to comment Share on other sites More sharing options...
kidblast Posted January 24, 2014 Share Posted January 24, 2014 well if you get nowhere with the next step.. know that Peavey is really good about that whole "Stand behind the product" thing.., and IME have always been very willing to help. Before you loose your patience, pick up the phone and call them,,.. you got nothing to loose... Link to comment Share on other sites More sharing options...
brc Posted January 24, 2014 Share Posted January 24, 2014 I just sent a reverb unit to Gegg Hopkins at Vintage amp restorations in St. Louis Mo.today.I have heard great things about his shop, so if you need to, you could also try him Link to comment Share on other sites More sharing options...
ksdaddy Posted January 24, 2014 Author Share Posted January 24, 2014 I think the tank is okay, as I used another (identical) tank and no change. I'm messaging with a Peavey guy and he's asking specific voltage/resistance questions but so far nothing weird. Except last night I was getting 14 volts at the tank and this morning it's 7.5. But over 15 minutes or so, it rose to 10 volts and likely would have gone back to 14 in time (I had to leave for work). Not sure if that's "anything" or just a predictable function of components warming up. Man, I am no amp tech. Link to comment Share on other sites More sharing options...
badbluesplayer Posted January 24, 2014 Share Posted January 24, 2014 I think you're on the right track. Link to comment Share on other sites More sharing options...
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