#1
I've got an old Traynor YGM-3 that was converted into a head at some point. Two days ago, it was working just fine with no problems. Today I turn it on, no sound whatsoever. Light turns on, all the tubes are glowing but there's no sound at all. Checked the speakers and cables and everything, swapped out all the preamp tubes, reset the circuit breaker (there is no fuse) still nothing.

I really don't know what else to do.
#2
There could be an internal HT fuse. They will blow when the power tubes fail (or are failing). When that goes, the tubes will still light up but no high voltage will be applied to the tube, just the heater current.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#4
You'd actually have to pull out the chassis and look for it. Sounds like you probably shouldn't be poking around in there tbh. But that's the first thing I'd do after checking the obvious external things, which it sounds like you've done.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band