Denon avr 2802 no sound on speakers but "works" - diyAudio
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Old 16th April 2015, 11:29 AM   #1
tufi979 is offline tufi979  Serbia
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Default Denon avr 2802 no sound on speakers but "works"

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.
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Old 16th April 2015, 03:33 PM   #2
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Have you got clock on pin 14?
You should be looking at IC108.
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Last edited by JonSnell Electronic; 16th April 2015 at 03:37 PM. Reason: More info
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Old 16th April 2015, 03:46 PM   #3
tufi979 is offline tufi979  Serbia
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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?
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Old 16th April 2015, 05:48 PM   #4
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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 ?
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Old 16th April 2015, 07:06 PM   #5
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Default service manual

here is service manual for denon avr 2802
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Old 16th April 2015, 07:07 PM   #6
tufi979 is offline tufi979  Serbia
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Here is service manual.
Attached Files
File Type: pdf Pages from Denon-AVR2802 rec 1.pdf (520.9 KB, 17 views)
File Type: pdf Pages from Denon-AVR2802 rec 2.pdf (264.2 KB, 13 views)
File Type: pdf Pages from Denon-AVR2802 rec 3.pdf (201.3 KB, 11 views)
File Type: pdf Pages from Denon-AVR2802 rec 4.pdf (167.7 KB, 13 views)
File Type: pdf Pages from Denon-AVR2802 rec 5.pdf (172.3 KB, 16 views)
File Type: pdf Pages from Denon-AVR2802 rec 6.pdf (135.1 KB, 11 views)
File Type: pdf Pages from Denon-AVR2802 rec 7.pdf (492.2 KB, 13 views)
File Type: pdf Pages from Denon-AVR2802 rec 8.pdf (377.7 KB, 13 views)
File Type: pdf Pages from Denon-AVR2802 rec 9.pdf (822.5 KB, 13 views)
File Type: pdf Pages from Denon-AVR2802 rec 10.pdf (509.3 KB, 12 views)
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Old 16th April 2015, 07:18 PM   #7
tufi979 is offline tufi979  Serbia
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And second part of shorter version
Attached Files
File Type: pdf Pages from Denon-AVR2802 rec 11.pdf (808.9 KB, 17 views)
File Type: pdf Pages from Denon-AVR2802 rec 12.pdf (469.1 KB, 13 views)
File Type: pdf Pages from Denon-AVR2802 rec 13.pdf (606.7 KB, 16 views)
File Type: pdf Pages from Denon-AVR2802 rec 14.pdf (848.0 KB, 13 views)
File Type: pdf Pages from Denon-AVR2802 rec 15.pdf (332.4 KB, 13 views)
File Type: pdf Pages from Denon-AVR2802 rec 16.pdf (804.6 KB, 13 views)
File Type: pdf Pages from Denon-AVR2802 rec 17.pdf (202.9 KB, 19 views)
File Type: pdf Pages from Denon-AVR2802 rec 18.pdf (809.4 KB, 16 views)
File Type: pdf Pages from Denon-AVR2802 rec 19.pdf (481.7 KB, 12 views)
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Old 16th April 2015, 08:26 PM   #8
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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.
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Old 17th April 2015, 09:06 AM   #9
tufi979 is offline tufi979  Serbia
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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?
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Old 17th April 2015, 09:18 AM   #10
tufi979 is offline tufi979  Serbia
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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 ?
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