On Feb 20, 7:05*pm, "N Cook" wrote:
jw51 wrote in message

...

The amp won't come out of standby unless the power cord is unplugged
for about 20 seconds.

Once you do this it will come on and perform ok.

It can be turned on and off with no problem and will stay running
indefinitely

When turned off for about 5 mins then won't come out of standby again.

I have just got a copy of the service manual looks like it may be the
power good signal.

Anyone seen this before?

Such delayed effects are usually due to chemical effects within electrolytic
capacitors, not necessarily the big ones. Check/monitor voltages over the
ones around the protection circuitry, they may form a battery-like
chemistry, so producing an offset, incorrectly interpreted as wonky power
rails .

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list onhttp://home..graffiti.net/diverse:graffiti.net/

Found the problem the power good signal was low instead of high.
Caused by low current in opto IC401 led, traced to C405 which is in
series with the 240V AC.
Difficult to diagnose as the area is at mains potential and there are
no voltages marked on the diagram.
The part of the circuit that regulates the standby 10 Volts through
opto IC403 was working ok.