Tweet
Hey everyone,
I'm working on a hot rod deluxe at the moment that has been worked on by someone else.. a bunch of traces cut and handwired on the board, recap, all the necessary servicing. I was told by the client that someone "spilled a bunch of beer into it" at a gig and that it was not working at all. I bring it into my shop to find that in fact it is working, but sounds terrible. The reverb isn't working (separate issue), but low V is supplying +16v / -16v.. so probably the tank.
I found on average the power supply voltages to be 30v higher than indicated on the schematic, and when the amp is turned off the caps are only draining to about 30v, which is much higher than other HRD's that I've worked on which usually end up retaining about 7v. Nothing seems to have been damaged by the beer, at least nothing is sticky. lol. There is a faint distortion underneath the clean signal that sound like some faint distortion that I would associate to voice coil rub in a speaker, but is consistent with multiple good working speakers. I cannot seem to isolate where the signal begins to do this on my scope as the signal looks relatively clean with normal crossover distortion at the output stage. I popped a set of new JJ 6L6's into the amp and was sent into runaway bias conditions. The tubes that originally were in there have a stable bias of 30mA each. So maybe a bad set of tubes out of the box. I don't have another set on me right now. So many goofy things going on with this amp. Any recommendations as to what I might be missing here? Thank you!
I'm working on a hot rod deluxe at the moment that has been worked on by someone else.. a bunch of traces cut and handwired on the board, recap, all the necessary servicing. I was told by the client that someone "spilled a bunch of beer into it" at a gig and that it was not working at all. I bring it into my shop to find that in fact it is working, but sounds terrible. The reverb isn't working (separate issue), but low V is supplying +16v / -16v.. so probably the tank.
I found on average the power supply voltages to be 30v higher than indicated on the schematic, and when the amp is turned off the caps are only draining to about 30v, which is much higher than other HRD's that I've worked on which usually end up retaining about 7v. Nothing seems to have been damaged by the beer, at least nothing is sticky. lol. There is a faint distortion underneath the clean signal that sound like some faint distortion that I would associate to voice coil rub in a speaker, but is consistent with multiple good working speakers. I cannot seem to isolate where the signal begins to do this on my scope as the signal looks relatively clean with normal crossover distortion at the output stage. I popped a set of new JJ 6L6's into the amp and was sent into runaway bias conditions. The tubes that originally were in there have a stable bias of 30mA each. So maybe a bad set of tubes out of the box. I don't have another set on me right now. So many goofy things going on with this amp. Any recommendations as to what I might be missing here? Thank you!
Comment