Need help repairing Denon AVR 5803

[sjdemark]

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.