"Arfa Daily" wrote in message news
Anybody by any remote chance have a schematic copy for a C - Audio RA 1001
slave amp ? Drawn a blank from all the usual places.

Looks as though it has been stored somewhere cold and damp, although dry
enough now. Basically, it won't come out of 'protect' although there seems
to be nothing wrong fundamentally with either channel. Both channels have
good output, with no DC offset, as far as the output relays. There is
another relay over at the mains input side of things that looks like it
shorts a bloody great resistor, so inrush limiting I guess. All three relays
remain stubbornly off, and the protect light stays on. I can't read any
volts at any of the three relay coils, and none of the pins appears to be
grounded, so they are not high-side switched. So may be something as simple
as a missing rail, but hard to follow print around as it's double sided, and
fairly crowded ...

Arfa



Check for corroded tracks around the fan area of the PCB, it was a common
failure, allegedly from corrosive smoke machine smoke.
Folow the relay coil tracks back to the protect circuit at the front of the
amp (I think) as ISTR it was often a break in this circuit that kept it in
protect.



That bloody great resistor is in fact inrush limiting shorted out by a
relay, (47 ohms?), and these often failed.

I might have a RA3000 schematic at work, will look tomorrow.
It is not a Crest.


Gareth.