Coleo said:
Thanks for the discussion here everyone. For background info the amp has never left my house or the outlet it is plugged into through a brand new musician-quality sound bar.
This statement caught my attention.
As far as I know, a sound bar is a piece of hi-fi speaker cab.
Do you plug the amp into a proper guitar cab? You don't say hence my questioning.
Also, plug the amp into other power outlets with nothing between the power cord and the outlet. And I have to say this (and I certainly don't mean to sound condescending): make sure your amp is plugged into a proper guitar speaker cab with a proper speaker cable (not instrument cable) before switching the amp on.
What we want to do is start a process of elimination.
1. Proper guitar cab with proper ohms?
2. Speaker cable (not instrument cable) connecting amp to guitar cab?
3. Try different power outlets throughout the house.
4. Use a new power cord to the amp.
If all the above are satisfied and the amp still switches in/out, call Mesa and discuss the problem. It's under warranty, so use it.
As mentioned in the other post, it could be heat related (expansion causing a disconnect). Who knows, it may just be a loose nut that needs tightening.
We look for simple diagnosis and quick solutions and sometimes they just don't come through. The PCB has plenty of components and wires. The components themselves can have internal parts (switches, pots, connectors). Anything can go wrong.