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Old 2nd September 2011, 06:17 PM   #1
diyAudio Member
Join Date: May 2008
Default Need help repairing Denon AVR 5803

Hi Everyone,
I have a problem with my Denon AVR-5803 and am hoping that an expert here can help me troubleshoot it. This receiver turns on for a few seconds, then turns off and the power light blinks quickly (twice a second). I have done quite a bit of searching and found this thread:

Help needed: Denon AVR 5805

I checked voltages on the regulator and stand-by boards, and all of the power rails seem to be there (as measured from the ribbon connectors and the regulators).

One think I noticed though is that while the voltages are all there, most of the input voltages going into the regulators are .2 - 2 volts lower than is specified in the service manual. The odd thing is that these supply voltages come from different transformers, so there doesn't seem to be a common problem. Also there are a few rails that are reading a few tenths of a volt low. What is the tolerance of the voltage that would lead you to consider a regulator problem? Just to make sure, I tried replacing some of these regulators with the exact part numbers, but it did fix the issue.

I enjoy repairing nice audio equipment as a hobby, and have mainly worked on bigger amps and a few receivers. However, this Denon is by far the most complex unit I have ever seen. I have the service manual which can be downloaded here:

DENON AVC-A1SR AVR-5803 Service Manual free download, schematics, eeprom, repair info for electronics

I would appreciate any help or suggestions to troubleshoot this monster.

Last edited by sjdemark; 2nd September 2011 at 06:24 PM.
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Old 29th January 2015, 08:52 PM   #2
diyAudio Member
Join Date: Mar 2007
Default AV-5803 protect flashing

Hi sjdemark; It is a few years since you posted your AVR-5803 problem. Guess by now you have long since repaired, but just in case, here is what I just found on the same model.

Left & Right sides are the Power Amp boards. Soldering is on the back side. Be care full when removing. The B+ & B- connections may still have voltage (64V). Tape them up when you remove the wires.

You need to Re-Solder the "driver" transistors TO126 type. There is a good chance that they have overheated & deteriorated the solder, especially at the centre lead. This is only ONE reason for 'protect' to activate. It is a very cautious receiver.

Worked for me... good luck
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