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?

parkergetdean

@seasidelps thanks! I know that if I open something and touch it, it will likely stop working. I want to avoid a $350 service bill. But all this info from you guys in empowering!
@ozzy62 @jl35 

I paid $800. I have no regrets. 

I sold my less powerful amp 2 weeks ago on USAM, tracked the shipment, followed up with him immediately if it arrived unharmed and the buyer said it was all good. 2 days later he emailed me that it had a humming noise when turned on. He wanted to send it back. 

I asked him to check a few things and move it and see what is humming. Never heard from him ever since, I assume the humming wasn’t a flaw in the amp. But I was sweating. 

Since my current amp WORKED for 3 days, and then it gave up, I don’t think I have ANY moral ground to return it. If it was new under warranty, then I sure would. 

I don’t think I could get a 150Watts amp for twice this price, this quality, new. 

 

 

looked Musical Fidelity A380 pictures, this amp has many fuses in critical high current circuits, therefore “only fuse” problem can be real! 

when you open lid, it would be good idea to check if amp didn’t have significant work done.. also, check solderings under mag-glass, if any visible cracks, board traces overheat discolorations etc..

good luck! 

Thermistors change resistance as temp increases so that would explain having to let it cool down to get that current inrush protection circuit working correctly again.  Again, should be easy to fix for a decent tech. 

@parkergetdean please remember, as there are many type of fuses, slow/fast/etc. before replacing “bad one”! simple $1 DMM check for resistance across fuse is simple step to avoid “pissing wrong tree” LOL!