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Old 2nd September 2011, 05:17 PM   #1
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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 05:24 PM.
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Old 29th January 2015, 07:52 PM   #2
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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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Old 8th March 2015, 01:35 AM   #3
cpuneck is offline cpuneck  United States
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I know this thread is old, but I have a similar problem with a 5803. I'm not an electronics technician but quite handy and have soldered many a board. Recently my 5803 began going into protect mode (I guess from reading here)... Power it own, hear the 3-5 relay clicks and right as the last one closes, there's an additional click (open I guess), display goes out and the power light just flashes.

Nothing had changed, no new connections or anything. Today I removed and replaced it with a Denon x4000 because it has HDMI and seemed like a reasonable replacement... wow it is nothing like my 5803 was! I'd put it in the anemic category at best. Anyway, after I opened up the 5803 to find the relay it stopped going into protect. Now I think it's a cold solder joint but I don't have the schematics and not a clue what area to start looking. This thing is full of relays

I've had problems in the past finding techs/company's that would go the extra mile in the repair of higher end electronics. (using standard grade components or 'generic' resulting in sub-par performance.) I'm hoping with the wealth of knowledge someone can point me in the right direction. At the least I want to use the amp in lieu of the x4000's.
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Old 8th March 2015, 05:36 PM   #4
pinyoro is offline pinyoro  United Kingdom
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If in doubt resolder all the joints in the solder area. You may also jiggle the components and see if you can see any movement of the component on the solder side.
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Old 8th March 2015, 06:00 PM   #5
cpuneck is offline cpuneck  United States
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Quote:
Originally Posted by pinyoro View Post
If in doubt resolder all the joints in the solder area. You may also jiggle the components and see if you can see any movement of the component on the solder side.
Thanks, that's a great idea, but I have no idea where to start looking for the bad joint.
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Old 8th March 2015, 07:06 PM   #6
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Quote:
Originally Posted by cpuneck View Post
Thanks, that's a great idea, but I have no idea where to start looking for the bad joint.
Look around the driver transistors for starters.

I blew an amp up once because I wasn't aware that the driver transistors were coming loose from the board. I touched one lead on a driver transistor with the VOM lead and one of the power transistors partially vaporized in a bolt of lightning. Then I realized that the driver transistor was loose; I was able to yank it off the board without desoldering it. Closer inspection revealed quite a few failed solder joints.

Maybe if I had reflowed the joints before testing it, it would have worked fine. I'll never know.
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Old 8th March 2015, 09:19 PM   #7
cpuneck is offline cpuneck  United States
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Man, sorry to hear that... I guess I'd be considered dangerous. I understand cold solder joints and how to properly fix'm, but I don't know the 'electronics' so pardon my ignorance if a question seems stupid.

When you speak of a 'driver transistor', would that be the 3 legged chip things affixed to the heatsink. (I thought they were MOSFETs)? I've had to resolder some of those on car amps... And replace a few.
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Old 8th March 2015, 09:36 PM   #8
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They should be smaller power transistors. Sometimes they are affixed to the heat sink along with the bigger power transistors, and sometimes they're not; but they should be distinct looking from the small signal transistors.

Look at all the solder joints close to the output transistors. Wiggle the parts while looking at the solder joint; especially larger parts. That way you can rule that out. If you're lucky, a little reflowing might restore function.
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Old 9th March 2015, 03:00 PM   #9
cpuneck is offline cpuneck  United States
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Ok, I'll set out to do some resoldering... There's a number of heat sinks and I'm not certain if it's just the two massive side units to focus on or some other areas as well (buried) in the belly of the beast. Seems what ever it is affects the whole receiver, not a particular channel When it goes into protect mode, in essence the whole unit shuts off and the pwr light blinks.
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Old 9th March 2015, 03:19 PM   #10
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Protection circuits typically shut everything down, no matter what triggers them.

You can check the inputs to the protection chip for a clue. It might lead you right to the fault.
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