Help! Express 5:25 having intermittent issues!

I registered here just to ask this question.

I have had my 5:25 almost three years. About a year into it, i started having this problem where in the middle of a gig or practice, the volume will start dropping down to almost nothing, then returning to normal. If i make any changes during an episode (like switch the wattage setting or channel) the issue immediately goes away, only to return after a minute or so. When it first happened, I replaced the power tubes on a whim. Problem solved. About a year later, the same issue again. Replace power tubes and done. Now it has reared its ugly head once more. I called boogie and spoke to a tech to see why my amp was eating power tubes. He said it was most likely not a powertube but a preamp tube issue, so on his advice I purchased a new MB 12ax7 and one by one switched them out looking for the culprit. The problem persists with the new tube in every slot. Today I purchased a matched set of el84s. The issue returned on brand new tubes. I made a large investment (for me) in this amp, and need it to function. Do you guys have any suggestions of what could be the problem? Also, if I send it back to boogie, has it been your experience that the retailer gives you a loaner amp? I need one

-JUS-

Modern EL84s are not reliable tubes and do not last. I just saw a Matchless owner say that he replaces them every 6 months!

You may have even gotten a new one that's bad.

Depending on where you live, you might have a decent Mesa/Boogie authorized repair person nearby. I've got a good one 15 minutes from my house!

You sure it's the amp? Does it happen no matter which channel/mode you have it switched to? No matter what speaker you plug in to? Let someone else plug their guitar and pedal chain into it and see if they get the same problem. Let someone else duplicate the problem using their own gear. Then you can be pretty sure its the amp that has a problem.

If nobody else can duplicate it, then start looking at everything you have in line before the amp.....

It does it even with just a cord plugged into the input, and my thumb over the end to make it buzz. The amp is completely stock. I have not considered it as a speaker issue, though. hmmm

http://forum.grailtone.com/viewtopic.php?f=30&t=43120

thanks for that, ifailedshapes!

Fast forward two months.

I had the amp shipped back to mesa, and it is now repaired. I just talked to Rich in service, who told me the problem was an intermittent fault in the FX loop send/receive. They replaced both jacks and added a transistor between the two that simulates a closed loop condition if nothing is plugged in. He said that with a jumper between the two jacks, I could have solved the problem myself (he also said the local music shop assured them they had tried this).

JUS said:

Fast forward two months.

I had the amp shipped back to mesa, and it is now repaired. I just talked to Rich in service, who told me the problem was an intermittent fault in the FX loop send/receive. They replaced both jacks and added a transistor between the two that simulates a closed loop condition if nothing is plugged in. He said that with a jumper between the two jacks, I could have solved the problem myself (he also said the local music shop assured them they had tried this).

Click to expand...

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.

BTW, jumping the effects loop didn't help me either.