My stereo amp (NAD 317) when I turned it on started making a ratcheting up buzzer noise which would last about half a second then 'start up' (some relay would click on and all was well)... This lasted a few days until this weekend when I was going to have a look at it but today it no longer switches on or anything, power = nothing ...
Take a look at the photo - I'm getting AC past the fuses at 'C' (checked the fuses to be sure) - and 15v DC at both left and right amplifiers +VL ('B' is left) - I dont see any negative DC though on the -VL wires (is there meant to be -ve ?).
I figure the noise had a typical relay buzzer sound to it and suspect it could the relay marked 'A' (48V 250VAC) - there are relays on the audio inputs, but I just don't think its them, of course I'm open to any suggestions as to what is going on...
Has some cap failed in the AC to DC power doohickey ?
~What to check, and how to check it ?
any help appreciated,