Denon avr 2802 no sound on speakers but "works"

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tufi979

Member
Joined 2015
#1
Hello to you all. I have been browsing for a couple of days now about my problem but i was unable to find solution so i will try here 🙂
I bought used Denon avr 2802 faulty. Receiver turns on like it should relay cliks it responds on all commands ( volume change on lcd, switching between sources , mode selector... ) but there is no sound , i downloaded service manual , i checked all voltages on supply rails and everything looks normal and as it should. I traced input signal from dvd input and signal is lost on TC9459N , there is input signal present on pin 5 and 24 , but no signal is getting out from it od pin 3 and 26. so i assume that this chip is faulty??? But this is present only on DIRECT and STEREO mode on every other mode there is no signal present on input pin of TC9459N. Yesterday when i powered it up i have noticed that there is slight sound on speaker but very very faint and this only happens when you powered it up as soon as you change input source and return it to DVD again there is no signal. I have checked all big amp chips, there is no short on any of them . I ran out of ideas where to check so any help will be appreciated.
Thanks in advance.
 
#3
Well i dont have osciloskope to check the clock but i made little amplifier for checking and tracing signal on board and as i can remember there is a hum on pin 14 on IC 805 . I dont know for IC 108 i will check and let you know , do you know how can i check if there is clock on that pin?
 
#4
i checked pin 14 on IC 108 and on IC 805 there is same buzz of hum i guess the clock is ok . Here is an update : when i bypass signal from input pin 24 to output pin 26 ( same as from pin 5 to pin 3 ) on IC805 i get input sound on speakers but without volume control ( i cant turn it up or down ) just constant tone as i can guess same level as input sound on pin 24. So do you have suggestion what to check ? This bypass confuses me , as far as i can see there is nothing that can amplify signal . so problem is somewhere in this section right ?
 
#6
Here is service manual.
 

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#7
And second part of shorter version 🙂
 

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#8
I used to work on a ton of these at a Denon Warranty repair center. Unfortunately you have a real dog with the problem you have. It's very common for this era of Denon AVRs and even Denon doesn't have a fix for it as far as I know. It's likely NOT related to any one component but a grounding issue in a digital circuit.

The only method for fixing these that has had a reasonable success rate is completely removing all the cards and cleaning, re-seating and soldering all of the snap in connectors.

I've spent countless hours with a scope and tried changing a lot of parts on these to no avail. You can try wiggling and pushing on all the cards and see if you get sound at all. That will definitely tell you if it's a connection problem.
 
#9
i tried that , although i didn't forced every connector to try that 🙂 i disassembled everything and clean the dust and resat everything back. and problem is same without change. Or maybe will be better idea to find some oscilloscope to verify signals. What do you think it is the enough range for oscilloscope 20Mhz for audio service ? I will not use it to much for servicing audio komponents, I rarely need oscilloscope i dont want to throw money away
So you think that i should check if clock is change on input pin of IC 805 when volume is going up or down and if there is change IC 805 is bad , and if it is not changeling then something before is wrong? right ? Or do you have better approach?
 
#10
Do you think that i should try to make jumper wire to act as ground and then connect it from chips ground to chassis and check if that is problem , do you think this could work as test ? and if this is problem to try to find where is it ?
 
#11
I have fixed many Denon receivers with the same problem you have described and I believe this is the the solution to your problem. On the DSP Board you will find a socketed IC(IC817). The socket itself is a surface mount socket and you will find one or two corners of the socket lifted from the PCB. All four corners are soldered to the PCB but become fractured due to stress. The solution is to remove the IC from the socket, resolder all four corners, resolder the socket leads and re-install the part(ensure correct orientation). ESD protection is required. The hardest and time consuming part of this whole repair is the need to remove the backplate so you can remove the DSP PCB. The service manual is available free online. As aways, your mileage may vary. Easy money repair...... Good luck.
 
#12
Unfortunately this didn't help 🙁 i tried that and same problem exist. Very low sound on max volume only in direct mode and as soon you change mode or input source sound stops and is no longer present ,when you switch it back to direct no sound until switch of and switch back on. Any more ideas ?
 
#13
I have similar problem.
But in my case when i do software restart (holding speaker A + speaker B button and turning on power) i get sound in speakers. It reacts on volume control but i can't do loud enough. After i change input the sound goes away.
 
#14
I have a 2809 which does not output anything from HDMI sources.
Could one of you Denon experts suggest where I might start looking for the problem?
I have an o'scope and I know how to use it so signal tracing is not a problem.
A link to the service manual would be a bonus.
Thanks.
 
#15
Hey guys.
As of today I have the fix for this. Took me months to do it, but now it's finished.
The problem is the flash chip on de DSP board. I has to be replaced with a working chip.
I have those chips 🙂 After replacing all is OK.
I can service the board , or send the chip, so you can do it yourself.
Mind you, it's a tricky solder job, not for the faint of heart 🙂

Regards, Henk
 
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