scottosan":1gz8lcgw said:
SavageRiffer":1gz8lcgw said:
CrazyNutz":1gz8lcgw said:
From what you described it's something between the input jack (would not rule out input jack) and where the pre-amp ties into the effects loop. Basically something in the pre-amp.
Possibilities:
input jack
Preamp tube, or socket
Cracked resistor
Bad solder joint
Short in a coax cable
Bad pot
Effects loop (have your tried bypassing it?)
None of this stuff is disastrous. The fact that you plugged into the return of the effects loop and it was fine rules out power section, and transformers.
I had a few exchanges with Friedman. He had me try a couple of things. I first replaced all the tubes. The second time around, I opened a few new Tung-Sols and tried those to make sure, but still the same. Dave told me to leave the 7025 in the 3rd preamp position and replaced the other two, but still nothing. Then I checked to see if it still worked through the return jack, and it did. Then right before I was about to turn it off, the channels started working again, except at very low volume. Maximum volume is like a 1 watt amp or something. I then replaced the 7025 back again with the Groovetube 12ax7, and it was still low volume except for channel 1 which got a little less volume. At that point, Friedman said they'd have to look at it themselves.
I am going to wager on it being the loop. Should be a quick and easy fix.
Friedman asked me to jumper the loop and see what happens, but no change. The only thin that happened in the end was at one point it just started making sound again, but at the volume of a 1w amp. It's not consistent because I replaced all the tubes with Groovetubes and JJ power tubes, but nothing. Then I opened a new pack of Tung-Sol 12ax7s and 7025, but still nothing. Then during the process of swapping tubes, the same came back, but such a low volume. In the end, I put the old tubes back in and the only difference from before is that it's now making sound, but faintly.
The 3rd time I used the amp was for about 1.5 hrs. That's when it suddenly just got quiet. Even if a preamp tube was the fix, I'm not sure it would have consistently worked again. Maybe there's a component overheating or something. However, of course the first thing I tried was swapping preamp tubes, but no change. The faint sound didn't come back until spontaneously later.
Maybe it's the FX loop or something else, but it's not a good idea to mess with the guy's amp. I wouldn't want anyone poking around it either if I was the seller. However, on the way to work this morning, something occurred to me. What if I were to spray contact cleaner on the tube sockets? Maybe there's some kind of connection issue in the preamp sockets. Hmm, I don't know. It might not be likely anyway because why would it just suddenly stop making sound? Wouldn't something with the tubes usually makes some noise, pop, or something? I've never seen an amp just go quiet and stay that way except for once when a fuse went out, but the whole amp stopped working when that happened.