So I think I may have figured it out. Thinking it might be a blown output transformer due to not having a load connected. Sometimes on dark and cramped stages with 30 seconds of setup allowed between bands, the main speaker out and extension speaker out get confused, resulting in no sound, an immediate power down and diagnostic (followed by a few minutes of embarrassment and worry). I probably toasted the OT (and maybe power tubes). Next step, testing the OT... Hopefully the fuse is the actual culprit and I can just pull the power tubes and test them one at a time, but I'm not holding my breath.
Question: This speaker jack confusion happened a couple times, the most recent was several weeks ago. If the OT were to fry from no load, would it not happen while there was no load hooked up? Would it be able to continue functioning for a month or two before dying?
Question: This speaker jack confusion happened a couple times, the most recent was several weeks ago. If the OT were to fry from no load, would it not happen while there was no load hooked up? Would it be able to continue functioning for a month or two before dying?