Denon AVR-810 protection

 

New member
Username: Razirafi

Post Number: 1
Registered: Oct-08
Hello. I just finished repairing a Denon AVR-810. I replaced the main output transistors, a few fusible resistors and a regulator IC. Now when I turn on the unit and I use headphones (no speakers connected), I can hear clean music and adjusting the volume control also gives out an increase or decrease in sound. When I connected the two main speakers (headphones unplugged), sound can be heard but when I start to crank up the volume the unit goes into protection mode. It does this even at a volume control setting of about 1.5 on the scale. Any ideas?
 

Platinum Member
Username: Nuck

Post Number: 11032
Registered: Dec-04
Why did you perform the repairs to begin with, Irwin?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 13073
Registered: May-04
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Did you repair the receiver or did you pay someone else to perform the repair?
 

New member
Username: Razirafi

Post Number: 2
Registered: Oct-08
Actually this receiver was repaired by someone else but since he could not complete it the owner asked me to complete the repair. I would have declined since it was already tampered but since the owner is a friend, I accepted it. The damaged parts were also sent to me and from those, I performed the repair.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 13074
Registered: May-04
.

Then it's possible the diagnosis wasn't complete or even correct.
 

New member
Username: Razirafi

Post Number: 3
Registered: Oct-08
It may be possible but I'm sure that the correct output transistors are in-place. Adjusted the bias to 2.5mV too. But why is it that the protection comes on only when there are speaker loads present. Is it possible that the output transistors are leaky? By the way I can read about 256mV DC on the output terminals. Should the DC reading be about zero volts?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 13075
Registered: May-04
.

You'll never get to absolute zero DC offset. But what you are reading would probably be quite high to unacceptable for many amplifiers. I don't know. I don't know your anmplifier and I have no reference for what readings you should find inside that receiver.

I would suspect it is impossible for us to diagnose any other problems over the forum. You need to do a proper bout of troubleshooting and diagnosis. If you think this was done correctly, then possibly another problem exists that was missed until the first issue was repaired. What that could be is your best guess. There are several places to begin searching and the power supply would be my first location to check. Are the new transistors installed properly with regard to polarity? It would be unlikely the transistors are defective if you used new, high quality parts. Any burned circuit boards or traces? Any shorted pins on the replaced parts?

The reason you don't have a problem with headphones is very likely the headphones are powered by their own IC based amplifier.

Do you even have a schematic for this receiver?

If you can't figure this out head over to AudioKarma's website.

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