JVC XP-A1000BK hall synthesizer
 

This unit is more than 20 years old, and has not gotten as much use as I
would have liked, for reasons I won't go into.

Several years ago, when I turned it on after a long period of disuse, the VF
display was scrambled and the unit didn't work. I let it "cook" for a day,
and the (apparently) malformed cap that was causing the problem decided to
behave itself.

Several weeks ago, I finally got my rear amplifiers, so the JVC was restored
to full-time service, and was working magnificently, until... You guessed
it.

About a half-hour ago, the display went dead and the outputs turned into a
not-too-loud digital "buzz". The input is locked at "digital". (The default
is analog, and you have to manually switch.)

My guess -- and this is only a guess -- is that this a power supply problem.
(The fact that all the channels went out does not automatically eliminate
any of the LSIs, unfortunately.) I have the service manual, but before I
start ordering mass quantities of electronics (or even start checking
voltages), I'd like to know if anyone has any views.

Please note that I don't expect anyone to diagnose what might be a messy
problem from a distance. (I'll call JVC tomorrow, anyway.) I just wanted
opinions.

Thank you.