Denon AVR-S710W Protect mode

[ajvpb]

When you turn it on it will power up for a few seconds, then kicks off and the red light blinks 2x/sec.

I fixed a Denon 4200W with the same problem which turned out to be shorted transistor on the amp.

All transistors on the the 710 check out.

Service manual is here: https://www.manualslib.com/manual/14...?page=2#manual

On page 99 on the service manual, on the bottom right of the first diagram of the pcb, is a connector that has all of the protection mode feeds on it. I am getting 2.2V on the ampsig_det line.

I am now out of my league as to how to trace whats causing this. If anyone has any experience or can point me to something obvious in the manual, I'd greatly appreciate it. I followed the flow chart on page 79 for protection mode based on the power amp, and everything checks out. The only part I can't verify is the last step that says power it on and check for an idling current.

Thanks for any hints
Alex

[petehall347]

Re: Denon AVR-S710W Protect mode

basically you want to see ideally 0v on the amp outputs .you can measure this before the relay .
as for idle bias its normally measured across an outputs emitter resistor .
to comment further i need to see a schematic of the amp .

try without loads connected to rule that out

[madan1]

Re: Denon AVR-S710W Protect mode

Service menu - page 20 - Special mode setting button (for AVR-S710W)
2-1 Protection history display mode - page See page 44
6 Protection Pass Mode - See page 49 ( do this only with current limiter )

[ajvpb]

Re: Denon AVR-S710W Protect mode

Yep, I checked protection history. 39 instances of dc protect. I'll get to the output voltages later when I get some time.

[ajvpb]

Re: Denon AVR-S710W Protect mode

Just to give an update in case someone comes along looking for a solution of their own....

It ended up being the regulator board. Somehow I overlooked the two blown fuses on the board. Further investigation revealed someone had replaced one of the regulators on it. When they put it all back together they lost an insulating washer on the screw that holds the 7912 regulator to the chassis. The heatsink tab on the 7912 shorts to the input leg, so when it was screwed down it was shorting the 17 dc volts to ground, blowing the fuses.

So, if all of your transistors are looking good but you're still getting a dc protect shutdown, make sure your other voltages are in order.