amp I bought 3 days ago not powering on - electrical engineer advice wanted

I bought a used Musical Fidelity A380 in good condition. Played it every day, worked fine.

Today it did not turn on. There were no sign of failure yesterday. Could it be a fuse or power supply?

parkergetdean01-29-2026 12:34am

gs5556 Details Discussions Posts This discussion Message User 1,274 posts 01-31-2026 at 04:45am Copy Comment URL Report Comment Edit Delete Looking at a schematic of the A300 and assuming the A308 is similar, the problem appears to be a bad thermistor downstream of the power switch. It is a $3 dollar part (Vishay SG27) and should require no more than a 1/2-hour of labor to replace.
parkergetdean OP Details Discussions Posts This discussion Message User 1,040 posts 01-31-2026 at 05:05am Copy Comment URL Report Comment Edit Delete Wow! Thank you @gs5556 that’s very precise! @devinplombier I have a few busted amps, good enough to practice
mark200mph Details Discussions Posts This discussion Message User 842 posts 02-08-2026 at 01:39pm Copy Comment URL Report Comment Edit Delete George Meyer downtown la is service for musical fidelity. I was just there 20 pluss techs oodles of electronic eq I was lusting after. Might give them a call ask a tech.i love my musical fidelity 500kw 550kw and cd spinners.i love the varister sound.its a tube developed for military to last decades.
parkergetdean OP Details Discussions Posts This discussion Message User 1,040 posts 02-08-2026 at 10:31pm Copy Comment URL Report Comment Edit Delete thank you @mark200mph !
rocray Details Discussions Posts This discussion Message User 1,542 posts 02-12-2026 at 04:35pm Copy Comment URL Report Comment Edit Delete @parkergetdean, any updates on your amp?