So I did all the normal things to check. The power tubes that were in it were quite cooked and old so I replaced with the spec Electro Harmonix EL84 tubes and used the multimeter to set bias to 25mv.
Still having the issue.
Whats happening here:
1) power on, seems all good and normal; no noises or anything.
2) it lights up the channels and shows ready for use. no issues.
3) flip the standby to go, amp comes on as normal.
4) ***the issue*** after a little bit like 5-10 min playing the sound turns all the way off, if you switch the channels or options on the tube settings to pentode/triode or from AB - A or from channel A to B channel sound comes back on but again only for a little bit them sound turns off again.
This is a recent thing the amp started doing. I thought that since the power section tubes were totally cooked and showed it that was probably the issue but now I'm running brand new tubes and still having the issue. any ideas?