Denon AVR-1912 E2/EA

[Michael Studio1]

I have found the reference to the Test Points - I knew it was there somewhere: Service Manual , Page 56. ADJUSTMENT Audio Section.

 

[Tha fios agaibh]

I have traced the L&R tones into IC30 (page130) and can go no further..Originally 'twisting' the PCB 'cage' would cause the Right tone to appear..

Congrats on getting power supply back up!
So, what was the problem all along, D801?
It's always a plus to understand what happened, so we can learn from it.

I'm not very knowledgeable on digital either, but I'll help where I can.

Ic30 puts out a 24 bit digital stream on pin 9 called DataD. From there it goes to Dir/Audio PLD section.

Originally, twisting the pcb caused the audio to come back. I would look meticulously for solder joints, hairline fractures of traces and component legs cracked.

You might get lucky and find the problem without having to go down the digital rabbit hole.

 

[Michael Studio1]

Congrats on getting power supply back up!
So, what was the problem all along, D801?
It's always a plus to understand what happened, so we can learn from it.

I'm not very knowledgeable on digital either, but I'll help where I can.

Ic30 puts out a 24 bit digital stream on pin 9 called DataD. From there it goes to Dir/Audio PLD section. View attachment 39833

Originally, twisting the pcb caused the audio to come back. I would look meticulously for solder joints, hairline fractures of traces and component legs cracked.

You might get lucky and find the problem without having to go down the digital rabbit hole.

And here on Page 126 there is yet another strange change of conductor name from: SDTO (IC30 pin 9) to DATAAD (in an identifier bubble) (rather like a speech bubble of cartoon fame) and ends up going from Page 126/D1 TO DIRECT AUDIO PLD (I wonder where that is?) though it must be on an HMDI SCHEMATIC as it's not a Connector Block.
Indeed! And I have just uncovered a mistake of mine (another one) above in which I refer to IC30 as being on Page 130. It is NOT - it's on Page 126. Another mea culpa event. The 'connector' here says that all those bracketed conductors go TO DIR/AUDIO PLD - I cannot work out what that is - and it must refer to a page or more in the Service Manual. Another misleading fact in this Manual is that Connector Blocks do not necessarily go to a Connector Socket with a similar number. 'Frinstance, on Page 129/H5 CN2 ADINR (pin32) is connected to CP11 ADINR (pin32) - Page 112/L4
To get to your question of 'What was the problem all along, D801?' D801 was my problem when I tried to separate one end of D801 from the pcb in order to measure current - and it ripped up the foil. Fortunately I was able to re-solder a new D801 (one of that 50 bulk purchase?) to the next in-line component. SO the problem (from which I hope to learn) was not a faulty component but a faulty DVM. I am replacing this DVM and the new one should arrive on Monday (BM235 Digital multimeter V DC60m/600m/6/60/600/1000V True RMS BRYMEN) from Amazon.
Michael Studio1 UK 18:29GMT

 

[Tha fios agaibh]

AUDIO PLD (I wonder where that is?)...all those bracketed conductors go TO DIR/AUDIO PLD - I cannot work out what that is ..

Page 33 shows the path going to HDMI boards. Ic22 eprom.

I suggest you change tactics and try another approach;
working backwards from audio output, instead of trying to follow the complex digital path from its origin.

 

[Michael Studio1]

Page 33 shows the path going to HDMI boards. Ic22 eprom.

I suggest you change tactics and try another approach; working backwards from audio output, instead of trying to follow the complex digital path from its origin.

Strange you should suggest a 'backwards' approach, John - for that is exactly what I had in mind! 'Great Minds' as they say. Michael Studio1 UK 21:42GMT

 

[Michael Studio1]

When this new DVM arrives I shall be able to carry out the tests shown on Page 56.
Michael Studio1 UK 00:03GMT

 

[Michael Studio1]

The new Meter, A Brymen BM235, has arrived and been pressed into use. However, the Tests given on Page 56 'ADJUSTMENT' adjusting the idling Current were not successful - in-as-much as although the required 0.002V.DC was achieved in most Channels, one or two seemed to cause the AVR to turn itself off. Yet I think there is some underlying cause for this which is nothing to do with these Adjustments. I am considering the case of the suggestion earlier:
"twisting the pcb caused the audio to come back. I would look meticulously for solder joints, hairline fractures of traces and component legs cracked."
So this is what I am intending to start doing tomorrow. But exactly where I should start on this I have no idea. Take each PCB at a time, starting at the SMPS, going through the SPEAKER_B'D . . . . I have already had an issue with the SMPS_B'D when the 2-pin Yellow/Blk Xfmr socket pins broke loose, the solder 'gave' causing enormous arcing down in the board. I re-soldered this and there appeared to be no collateral damage. But 'appeared to be' is the issue and I must look more closely. Now I shall take the rest of Sunday off - and away from the Lab.
Michael Studio1 UK 19:48GMT - a good year 1948, I was a Cathedral Chorister at Peterborough - 'O For the Wings of a Dove' &c.!!

 

[bushtech]

This is where your Android endoscope could be invaluable

 

[Michael Studio1]

This is where your Android endoscope could be invaluable

Thanks, Bushtech, I'm not sure how the endoscope can be utilised - but it's truly amazing and was extremely useful in placing my sharp probes on those small pins. Michael Studio1 UK 22:16GMT

 

[Tha fios agaibh]

Look for dry cracked solder joints like this.
Sometimes you'll see slight concentric rings that are a tell tale sign of a bad joint.
(Image courtesy of Google)

 

[Michael Studio1]

Look for dry cracked solder joints like this.
Sometimes you'll see slight concentric rings that are a tell tale sign of a bad joint. View attachment 39863
(Image courtesy of Google)

Thanks, John - that was one bad PCB! Good, helpful illustration of what to look for. Michael Studio1 UK 06:23

 

[Michael Studio1]

C823 is in the +7V. rail at J5.on Page114. Michael Studio1 UK 20:39GMT

 

[Michael Studio1]

Any idea which IC is the DA converter? Maybe if I look at all the IC's in the Parts Lists I'll find the answer.
Am attaching some TaggedTestTails in the FR & FL SPKR Ccts. going back to the 7CHANNEL amp B'D. Again there are changes in nomenclature of the plocketry. 'frinstance CN1 (page 108/A3) is connected to CP402 (page 106/03). I'm also removing some of the TaggedTestTails used in the +8V.-8V. rail disaster. Well, now it's resolved the disaster is averted. Michael Studio1 UK 19:15GMT

 

[Tha fios agaibh]

Any idea which IC is the DA converter?

Looks like IC29.
Digital comes in on pin 14 and outputs analog on pins 1 and 2

 

[Michael Studio1]

(there are 7 Test Points on the 7Channel B'D - where I was taking those Idling Current readings from - (see Page56) I have included TP401 in the following trace since pin 3 in this Test Point may allow the Audible monitoring of the FL Channel.

View attachment 39909 Looks like IC29.
Digital comes in on pin 14 and outputs analog on pins 1 and 2

Yes! You are right, John. I find there are 5 pins involved: on IC29 Page 126/G6. Pin14 (SD111) is Digital IN. Analog OUT = pin1[LOUT1-] pin2[LOUT1+] pin47[ROUT1-] pin48[ROUT1+]
In tracing the Analog from IC29 I shall take the [LOUT] pin1 route = [FL-] -> IC28(A) - pin1 FL - [DAFL> Page126/N4 - [DIGITAL CNT] Page129/E4 <DAFL] = CN2 pin 28/H5 -> [FRONT CONNECTOR] Page112/L3 CP11 pin28 -> CP115 pin13 DA_FL -> AV 1/3 Page114/F1 - CN115 pin13=DA_FL - IC801 pin93 D/A_FL (page118/F8) - IC801 pin 21 FLOUT - [AMP_FL> -CN401 pin1 FL (page114/O3) to 7CH_AMP (page106/A4) CP401 pin1 - [FL_IN> - TP401 pin3 - CP402 pin1(page106/O3) - SPK_SMPS (page 108/A3) CN1 pin1 FL - RLY2 (page108/D2) - JACK1 FL_A (page108/M2) That's the trace. Until I get the AVR re-assembled again and powered up I shall not know whether my understanding of another aspect of the TestPoints TP401 - TP407 are correct but I think Audible Monitoring from all seven TP's at pin 3 will be possible. The Cct.Diags seem to imply this. If so, this is a useful thing to know. I have yet to determine where my new 'TaggedTestTails' will be. Michael Studio1 UK 15:01GMT.

 

[Michael Studio1]

All PCB's are back in, ribbon cables reconnected, power cable from wall outlet inserted and the AVR powered up. Unfortunately the power didn't stay on and almost immediately turned itself off. I have checked for stray cables and ribbons. None. No obvious forgotten connections. So I shall take the rest of the day off . . . . . Michael Studio1 UK 21:51GMT.

 

[Michael Studio1]

AVR turns on for about 5secs. then Red flashing around 'ON' button. I have followed TROUBLE SHOOTING on Page 61 of the Service Manual - on: Check Voltage of CN8 (page 129/H8) pin1 (Yellow) = +2.7V. reference AGND. pin5 (Black) = +3.8V. ref. AGND. Now refer to Page23: 2. Errors checking mode: Starting up: [AVR-1912E2/EA model] Unable to perform any mode setting as AVR switches off in 5 secs. Michael Studio1 UK 17:34GMT

 

[Tha fios agaibh]

I believe its going into protect mode because it is sensing an overload.

Make sure your speaker impedance isn't too low. I'd disconnect all external wiring to see if problem goes away. (No external shorts)

If it continues to switch off (with no external connections), there must be an internal short or the circuitry that monitors current or temperature is throwing a flag.

I'd guess it's that lost left(?) audio channel thats overloaded (shorted) and that's why it turns off after 5 seconds.

Your one post with all the test point facts was a bit hard to follow. (too much info for me to digest) Let's stick with basics for now.

Do you get any analog audio output from pins 1 and 2 of Ic29 with respect to Agnd?
(I don't know if you can within 5 secs)
.... How about with respect to some of the other ground references?

 

[Michael Studio1]

I believe its going into protect mode because it is sensing an overload.

Make sure your speaker impedance isn't too low. I'd disconnect all external wiring to see if problem goes away. (No external shorts)

If it continues to switch off (with no external connections), there must be an internal short or the circuitry that monitors current or temperature is throwing a flag.

I'd guess it's that lost left(?) audio channel thats overloaded (shorted) and that's why it turns off after 5 seconds.

Your one post with all the test point facts was a bit hard to follow. (too much info for me to digest) Let's stick with basics for now.

Do you get any analog audio output from pins 1 and 2 of Ic29 with respect to Agnd?
(I don't know if you can within 5 secs)
.... How about with respect to some of the other ground references?

Hello John - When first testing this AVR I was using Chassis GND - that was a mistake - as I discovered. All Voltages (other than Relay) are taken with respect to Agnd. I was getting all sorts of spurious readings until I appreciated this. Audio readings, however, may be different? Sorry about the complexity of my Test Point Facts: It was intended to enable anyone with a copy of the Service Manual to follow - page-by-page. Even I couldn't follow it without that! (I tried) You make a Very Valid Point! (about removing test points which I have wired in.) I'll first try removing them - just to see if . . . " it goes away " Until I get the AVR to stay 'ON' I can do further checking - and those 'TaggedTestTails' are the only foreign things on the AVR. I have nothing attached anywhere else. So. Out with the soldering iron! Michael Studio1 UK 10:28GMT

 

[Tha fios agaibh]

Ok, just trying to eliminate the possibility that something you have connected may have a short. If your confident your test tails are secure, by all means leave them if you need further testing.

Do you still have +/- voltage rails where it needs to be?

When I asked to verify analog out, I meant for you to probe with your amplified speaker to hear if you have line level output.
I presume if there's a fault, it'll likely be in the final amp stage.