My Laney LC-30 tube quitar amplifier stopped working yesterday during rehearsal. No sound at all. Both channels out, but looked like the channel switching worked and power lights are ok. After couple of minutes and playing with the power switch couple of times the sound came back and stayed on for hours, even kicking the amp didn’t make it cut again.
During the outage the tube ‘lights’ warming was out, so that explains the lack of sound. As tubes don’t work at all without the warming.
I suspected it could be power switch if it connects multiple voltages from one switch. I opened the amp and looked like the power lines were never fully plugged in. I tightened the connectors and plugged them fully in. And it seems to work. But only longer test shows if this really was the issue.