Mark IV losing all sound

[Force]

After playing through the amp and having it on for a few hours continuously at practice, the amp sound suddenly faded out and sound died out totally.

The amp was still on, but no sound at all. I shut it off for a few minutes, then powered up, left on standby a minute then turned amp on and it was fine for a minute or two. The volume surged louder, then died out again. Let amp off for five minutes and it was okay.

The Mesa 6L6 power tubes are new: I replaced a pair last week, and the outer pair two weeks previousll. The preamp tubes are a few years old. No squeals or microphonics.

I'm wondering if it is overheating? The head shell is sitting on top of my 2x12 recto cab, and it's warm in our rehearsal space, like 75 or so degrees.

 

[Promethean]

Tried swapping back the old power valves? Be good to eliminate a bad tube. Are any tubes redplating and going buzzy before they fade?

 

[Force]

Tried swapping back the old power valves? Be good to eliminate a bad tube. Are any tubes redplating and going buzzy before they fade?

Yes, definitely was making the buzzy sound before fading out altogether. The tubes had a normal glow as far as I could tell after the sound went away. I dont know about redplating, Im not familiar with that term, but I didnt see any unusually bright red inside the tube glass on any of them I was running in simulclass btw.

 

[Force]

Happened again last night. Played great for 4 hours, then just kind dropped in volume for a couple minutes, then no sound at all. I have a call in to Mesa Tech support, but have not heard back yet.

 

[Authorized Boogie]

Happened again last night. Played great for 4 hours, then just kind dropped in volume for a couple minutes, then no sound at all. I have a call in to Mesa Tech support, but have not heard back yet.

I did get your call, but the phone number was unintelligible.

This does not sound like a power tube issue. Have you done any preamp tube troubleshooting? With the intermittent nature of your issue, something besides a tube issue may be more likely.

 

[Force]

Happened again last night. Played great for 4 hours, then just kind dropped in volume for a couple minutes, then no sound at all. I have a call in to Mesa Tech support, but have not heard back yet.

I did get your call, but the phone number was unintelligible.

This does not sound like a power tube issue. Have you done any preamp tube troubleshooting? With the intermittent nature of your issue, something besides a tube issue may be more likely.

Thanks very much for the reply. I will call back. I suppose I need to look into sending in to y'all to go through and get er fixed up.

 

[Authorized Boogie]

Happened again last night. Played great for 4 hours, then just kind dropped in volume for a couple minutes, then no sound at all. I have a call in to Mesa Tech support, but have not heard back yet.

I did get your call, but the phone number was unintelligible.

This does not sound like a power tube issue. Have you done any preamp tube troubleshooting? With the intermittent nature of your issue, something besides a tube issue may be more likely.

Thanks very much for the reply. I will call back. I suppose I need to look into sending in to y'all to go through and get er fixed up.

Definitely try a thorough tube troubleshooting first...as well as checking all cabling, instruments, etc - and trying in another location with different power. If all else fails, we've got an amazing tech in Dallas - OR - here at the factory. Thanks!