Hello all. I recently bought my first Peavey 5150 (combo 2x12 - used) and I believe there is an issue with it. I am posting here to (a) confirm my thoughts and (b) perhaps get some suggestions on repairs (JerryP, are you around yet?)

When I turn the amp on, let it warm up, and then turn the standby switch on, the amp hisses and makes crackling / popping sounds. At this point, all knobs are at "0". If I leave the amp on for a while this way, it continues to make crackling / popping sounds.

The tubes are in perfect shape (they are *new* JJ's 12AX7-short and 6L6GC) and all tested perfect in a tester and in my Marshall, so the tubes are NOT to blame. Interestingly enough, if I pull tube 3 from the amp and turn it on, the amp is dead-quiet. If I pull tube 2 or tube 1 and turn the amp on, I get the crackling / popping sounds. I can only guess that its something between the plate of valve 2B and plate of valve 3B that's causing the crackle. I have the schematic and I've been reviewing it, but this amp is quite a monster compared to my Marshall JCM800, so I haven't removed the chassis and started diggin' into it yet.

I've heard this type of sound before in my Marshall when I had a bad solder joint on V1 ... or perhaps one of the relays is bad/damaged (why couldn't peavey use optics like Mike Soldano did?)... but I'm just guessing at this point.

Anyone have any ideas? Maybe this is a common problem; I don't know.
Thanks in advance for any help you could offer.

You should have tested it out,but consult the source you baught it from.

Possibly bad preamp/power tube sockets? This happened to my JCM800 and it was the same symptoms you speak of.But the 5150 is so hard to work on becuase the pots/tubes sit on the PCB from pics I have seen.It sounds like bad tube sockets to me though,or possibly the filter caps going bad too.

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