427Cobraman wrote:
Have both a DE845 and DE945 and also have the service manual. Neither
unit will power on. The 845 had chattering power and I found bad
solder joints in the display board. After repairing those, the unit
ran for about a minute and a half then shut down...never to restart.
All fuses are good, and the standby power circuit seems to be working
fine. When pushing power button nothing happens (front panel or
remote). So, I'm assuming there is a problem with the standby
circuit. According to the schematic, the main power x-former is off
until the the standby relay is switched on, so ruling out that area.
Is there a built-in protect that prevents unit from coming out of
standby? I took voltage readings earlier but will recheck them one I
get home and post them. BUT, if memory serves, I had 5vdc out from
some terminals and 10-13V on the collector of Q901 which supposedly
powers the relay (RY901). I'm looking for guidance on how to
approach this problem. I'm proficient with O-scope, DVOM, ESR meter,
and general electronic repair. Just never messed with audio
receiver/amps before. Thanks,

Alex

OK, I was wrong about the resistors - guess I was thinking of a different
model.

Check Q1205 on the digital board and make sure it's putting out around 6
volts or so - and check D1211- it could be open or have been breaking down
under load - which kind of seems like your problem. Make note of whether the
micro is getting hot, or is stone cold. Could be an important clue.

Mark Z.