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Post by mastertech on Jul 19, 2014 20:18:59 GMT -5
Have you verified that is the problem board?
1U-3799 is not showing available but it is showing to be an over 500 dollar board.
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Post by mastertech on Jul 20, 2014 8:29:46 GMT -5
Also, the AVR-2808CI, that one doesn't have LAN capability, but has the same issue, what would be the cause on that one? The 2808 is also updateable but just not via LAN. But I also have to say that I am not convinced in any way that this problem is even firmware related. It just would of been nice to have been ruled out. I will start looking over the schematics later to see where we might be loosing this sound at. |
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Post by jeremy on Jul 20, 2014 20:15:51 GMT -5
Have you verified that is the problem board? 1U-3799 is not showing available but it is showing to be an over 500 dollar board. I haven't yet, no. I will swap the HDMI boards out in the morning. Hopefully the HDMI board isn't the problem, or if it is, it's something repairable. At least it's good to hear that the firmware not updating isn't the only possible cause. I love the receiver actually. I wish my AVR 5805 had a few of the features this one has. |
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Post by jeremy on Nov 19, 2014 12:15:58 GMT -5
Well MT, I know its been a loooong time since I posted back on this one, but I finally got around to it today!  I pulled the covers off both the working and non working AVR, and removed both the HDMI boards from each unit. Each board is almost identical, but the working HDMI/Digital board is actually an older revision, there is a soldered on jumper between connectors CW114 and CW133, Pin 9 CW114 to Pin 2 on CW133. The non working board has a couple of capacitors soldered onto IC501 and IC901. Other than that they appear identical. On both boards I checked those IC's along with all the other 'BD' ICs on both sides, and I also checked IC801, IC802, IC803, IC805, and IC511. Sure enough IC803 on the bad board has a very high reading in diode scale on one pin vs the good board, IC805 and IC511 on the board also read very out of spec on the bad board vs the good board. Also the 2 IC's with the capacitors soldered onto them, they also read off, but I wasn't sure if that was a result of the capacitors on them or not.. I can't check this board while the units powered on, its all sandwiched together when fully assembled, and impossible to reach half the parts I just mentioned. I am assuming these are power ICs? What would be the next thing to do? I am ready to order parts if that's what needs to be done next. I guess I'm looking for your thoughts on if this is indeed whats causing the problem. Sorry it took me so long to get back to this!! |
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Post by jeremy on Nov 19, 2014 12:22:10 GMT -5
And by way off I mean some of the pins read almost shorted or open vs what the good board read. If you need specific #s from the diode readings I can give them to you
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Post by mastertech on Nov 19, 2014 15:57:54 GMT -5
Ok, I am going to have to get back up to speed on this one.
Are these 2 HDMI boards from the same model or different?
Have you verified this board is definitely the problem? You swapped boards and the non working one then worked?
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Post by jeremy on Nov 19, 2014 19:31:41 GMT -5
These 2 HDMI board are from the same exact model, AVR-3808CI. I have not yet swapped the boards, in fear of the other AVR killing the good board lol. If you tell me to, I will  The reason I am 99.9% sure on this is because the parts I mentioned on the bad board read significantly different from the working one. That, and I also found a forum somewhere on the internet from a guy who serviced several denon models like this one and similar, and he said a lot of the time it was bad power regulators or something like that, I don't remember exactly  |
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Post by mastertech on Nov 19, 2014 20:51:18 GMT -5
Ok, we will assume for now to pursue your hunch.
Based on you getting different reading between boards we will start some checking there to verify. Can you assemble the non working one enough to turn it on? And if so can you access the digital power board (1U-3817-1) and test for DC voltage at CW028, pin 2 for gnd and pin 1 for 3.3v. If you can also on the same board check CW027, pin 2 gnd and pin 1, 3.3v and also CX121, pin 10 gnd and pin 6, 3.3v and pin3 gnd and pin 1, 5v
If you cannot access these connectors when assembled let me know and I have options.
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Post by jeremy on Nov 20, 2014 10:20:27 GMT -5
Okay I can't test right on the PWB itself, but CW027 and CW028 go right to the HDMI board so I was able to test off of there. I am assuming the little white dot by the pin indicates pin 1? If so, then CW027 reads -171mv (if probes are reversed it reads positive), CW028 Reads -36mv (again if probes are reversed it reads positive)
As for CX121 I have not yet located it, is it on the digital power board as well?
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Post by mastertech on Nov 20, 2014 11:00:12 GMT -5
Yes it is. But lets not worry about it for now since you don't have the other voltages. Is the unit turning on?
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Post by jeremy on Nov 20, 2014 12:33:00 GMT -5
Yep the AVR turns on and "works" except for the obvious issue we're attempting to repair
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Post by mastertech on Nov 20, 2014 16:07:45 GMT -5
Ok, then on this power board (1U-3817-1) you need to find fuse F801 and see if it is blown.
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Post by jeremy on Nov 20, 2014 17:48:50 GMT -5
F801 is good, shorts down to 0 no problem.
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Post by mastertech on Nov 20, 2014 21:07:06 GMT -5
Something is going on in this circuit. I am assuming the main transformer is engaged since the receiver works. But this section of the main transformer could be blown. So check for Ac voltage at cx031. Or check for DC voltage somewhere as indicated. I did it this way so you can see where you can test when powered up depending on what you have access to. I doubt if you have 2 regulator blown so look at supply lines. But it could be possible of 2 reg bad. The third reg is also supplied here which feeds the other connector you did not test previously cause you could not find it. Let me know what you find and I will guide you further.  |
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Post by jeremy on Nov 20, 2014 21:21:29 GMT -5
I checked CX031, it reads +17.88vdc . I couldn't check for DC since I couldn't find where to test off of (I cannot access the bottom of the CPU power board so I have no idea from the top where I can test off of)
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I pulled the covers off both the working and non working AVR, and removed both the HDMI boards from each unit.
