Channel 2 dead

[boyscout]

Channel 2 on my MKV has gone dead, the others seem fine.

I called Chris at Mesa last week, and he quickly thought that the V2 tube would be the problem. No joy. I wanted a spare tube anyway.

I've been hearing white noise and buzz on all channels for a while. Since I've been putting together a system with lots of other gear, and my power is well-conditioned, I figgered I had a ground issue I'd have to track down once I got all the components settled into place.

Suddenly last week I noticed the amp was quiet. Very, very quiet on channel 2! :lol: The other channels sound fine.

Since the V2 tube doesn't seem to be the problem, is there anything else simple I can check before I give up the amp for medical attention? It is quite young, only a few months old and less than 15 hours of light home use, no moving or gigging.

TIA

 

[APEMAN]

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[boyscout]

Apeman, thanks for your time, interesting idea. Hoping that I understood your advice properly, I went down to fiddle.

The FX loop and the external (RJM) switcher and devices it controls seem to work fine on channels 1 and 3.

While testing I noticed that channel 2 is not completely dead as I'd thought. The Master on all three channels is at about 8:30; channels 1 and 3 put out loud-enough-for-home signals. Channel 2 is so low that I didn't hear it at all last week, but this morning two feet from the cab I can hear faint output.

The output does get colored by the FX loop if I engage it, but not in a good way! A Big Muff Pi for example sounds like one on channel 1/3, but on channel 2 it produces noise and a very large bump in volume, all buzz and hum, no guitar or musical fuzz. Other devices are the same; they produce a volume bump of some size but don't sound like themselves since there's almost no guitar, no musicality. I guess each of the pedals' gain is kicking in but doesn't have much signal to process? Just a guess.

Does this offer further hints about the problem?

 

[APEMAN]

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[boyscout]

I know just enough not to kill myself, but this is a nearly-new amp and I don't have a schematic for it (where did you get that?) so it's off to the hospital for warranty service. I'll let you know the issue when I get it back. Thanks again for your time.

 

[APEMAN]

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