Volume cutting out

[espresso]

It has happened three times that after playing the amp for a couple of hours the volume starts to cut out. I pushed the jack in harder and the volume would return so I braced it tighter with an elastic. After another 15 minutes the sound cut out for good. Turning the amp off and back on again didn't help unless I left it off for a long period of time, at least an hour. This has happened at various times even though I've changed preamp and power tubes. The tech where I purchased it said that there is nothing wrong with the amp. Any ideas? BTW, all the lights stay on even with the sound gone.

 

[vbf]

I was having the same problem. I spoke with a guy very knowledgeable with tubes and he thought it was either the power tubes, phase splitter (V4 preamp tube), or a weak tube socket solder joint that fails at high temps. I started at the power tubes and that seems to have fixed it. But I keep a couple 12AX7's handy to replace V4 juuuuust in case.

 

[EtherealWidow]

I dunno man. That almost sounds like a soldering issue being that it was fixed when you pressed it in harder, but then no sound at all. Maybe it finally broke that solder joint. Should be a pretty minor repair, but what do I know.

 

[espresso]

I'll try replacing V4 again, this will have been the fourth time! The power tubes are only a few months old. The tech at the dealer checked it out and found nothing wrong. I wonder if he did check for loose solder joints.
A Mesa tech told me that in the last 5 yrs preamp tubes have been declining in quality and it's not uncommon for Mesa to go through 10 - 15 different tubes to find good ones.

 

[J.J]

Thats interesting about declining tube quality. My Mesa dealer told me that Mesa are now using JJ 12AX7s (Have not verified it for my self though). My amp which is an older one and has a 4xxx serial number came with the Sovtech tubes or whatever they are.

 

[vbf]

I had a problem with my volume cutting out Wednesday night after the amp had not been on an hour. I turned it off then turned it back on.....fine. I called Mesa yesterday and Mike Taylor suggested that I change out V1 and V2. I recently replaced the power tubes so I'm doubting those are the problem. The only 12AX7's I had laying around are stock Mesa's so I put them back in. I'll report back if anything new develops.

 

[JUS]

Put a jumper between the effects send and return.

 

[JUS]

http://forum.grailtone.com/viewtopic.php?f=30&t=43082

 

[vbf]

Put a jumper between the effects send and return.

I use the effects loop all the time, though. Thank you for linking the thread, very helpful.

 

[FXR]

I just sent my Mesa Express 5:25 back for this reason. It took months and quite a few tubes to determine it's not tubes or the speaker. I hope they can solve the problem.

 

[CHATTERBOX]

My 5/50 112 had a similar problem. Volume cutting out but everthing else was alive. I took it in and the tech at Long and McQuade (Oshawa Ont. Canada) cleaned ALL the jack connections. $17.50 problem solved.