Electronic equipment repair and service manual search discussion :: Topic review - Denon A/V receiver AVR-1604 powers off

jts1957 · Posted: Fri Feb 06, 2009 4:29 am Post subject:

Ya gotta have a little fun every once in a while. Laughing

dahbrown · Posted: Fri Feb 06, 2009 3:28 am Post subject:

Thanks for the vote of confidence!!!!

All good now, the replacement -15v regulator was actually faulty when I bought it, it was shorted input to ground, hence the reason why the resistors blew too.

Not sure what caused the 7915 to blow in the first place.

A simple fix in the end!!!

Many thanks for you guidance

Dave

Xtech · Posted: Wed Feb 04, 2009 9:01 pm Post subject:

jts1957 · Posted: Wed Feb 04, 2009 7:58 pm Post subject:

You could always jumper across the fusible resistors and "follow the smoke" Rolling Eyes

dahbrown · Posted: Wed Feb 04, 2009 4:12 pm Post subject:

There is no voltage on the -15v rail. The resistance was around 400 ohms. Also discovered that the resistive fuses from pin 4 and pin 6 from the supply voltage (R141 and R142) were open circuit too. So replaced them and they blew once unit was powered on. In stand-by mode all is OK. Need to power up via remote control, during POST this is when the unit is turning off after 3-4 seconds.
Next plan is to short the power relay to isolate the bridging board and CPU board and determine that main board is OK?

jts1957 · Posted: Tue Feb 03, 2009 11:32 am Post subject:

What is the voltage and resistance on the minus 15 volt line?

dahbrown · Posted: Tue Feb 03, 2009 7:29 am Post subject:

Sorry, my mistake! Yes it is the -ve 15v rail.

I replaced the 7915 and same thing occurs, powers on and then during POST it shuts down. I removed all input cards, which just leaves the main board, bridging board, CPU and front display.

How am I am able to isolate the fault, as I have checked the diodes on the CPU board which seams to have the -15v rail on it. But could it be the CPU or bridging board.

Thanks

jts1957 · Posted: Mon Feb 02, 2009 1:51 pm Post subject:

Something's backwards.
That would be minus 15 volt regulator (Or 7815 for positive 15 volts).

dahbrown · Posted: Mon Feb 02, 2009 8:19 am Post subject:

Found that 15v regulator is stuffed. Suspect that 15v rail on the analogue input stage is shorted. Just need to get a couple of spare 7915 regulators to prove...

dahbrown · Posted: Sat Jan 31, 2009 3:54 am Post subject:

Thanks for that. What votage values and where should I start probing?