Denon AVR-1912 E2/EA

[Michael Studio1]

I have the 'Denon Service Manual Ver.6' (down-loaded free and printed - 196pp.) which I am using to check my findings. Essentially the problem is that the Operating Voltages required by the Service Manual shown at various points in the Circuit Diagrams, are not being met. Another problem is that the whole 'build' of pcb's cannot be dismantled since the integrity of their physical inter-connectivity with each other is required - or else the unit shuts down. Each pcb is connected to other pcb's by 'edge connectors' - this is a physical as well as an electronic requirement. In order to remove the can covers and still preserve electronic integrity I have had to remove the back panel and connect together all the GND points (the attachment tags to all connectors like hdmi. rca and speaker) using bare wire connected to a common GND point. This works. But it is still not possible to remove any of the pcb's from the structure without the power turning off. Therefore I have devised a method of creating 'Tagged Test Points' by simply soldering short lengths of thin black-insulated jumper-wire to various otherwise inaccessible test points/connector blocks as shown on the Cct. Diags. This both preserves the integrity of the built stack of pcb's and allows readings to be taken at these points.
I am using a UNI-T UT61E dvm for this. To check the tiny connections to, say, IC801 (pin30) I am using a long, sharp insulated probe in conjunction with an Endoscope - and view this on the Lab computer.
Is there anyone who can offer advice on testing such a beast - PLEASE . . . . Michael UK

 

[kellys_eye]

The common denominator is obviously the power supply. This should be readily separable and still be 'connectible' to the main unit as there will only be a couple of output voltages/rails.

If you can be more specific about the fault symptoms this may also assist.

But given that such units usually rely on a SMPS voltage source and that these circuits are very susceptible to problems it shouldn't be too difficult to fix.

 

[Michael Studio1]

Thanks for your reply, Kelly's Eye. Indeed you have given me hope - and a good starting point. I shall start on this right away. I shall remove the 'cage' comprising: HDMI+FRONT+SIDE+AUDIO-VIDEO pcb's and see if the AVR still powers up. Historically when I bought this AVR it had an Audio problem: of the two signal tones injected into AUXL and AUXR, only AUXR was getting through to the Speaker terminals. The signal tone from AUXL got lost somewhere - but was intermittent and could be made to get through to the L Speaker Terminal by applying torsion to the 'cage' of pcb's. On the AUDIO_VIDEO B'D that oblong IC801 was only handling the AUXR signal - AUXL, being intermittent didn't always get that far. I have had this 'cage' dismantled and rebuilt many times in my search for the AUXL signal. Then there was a change and the +8V. rail changed - so nothing worked. Why this happened I don't know - but it was obviously something I had (or hadn't) done. So I devised the use of 'Tagged Test Tails' to monitor at least two pins at chosen Edge Connectors to monitor the +8V. rail. This is where we are now. I shall report back! Michael, UK

 

[Michael Studio1]

On the SMPS B'D (page 100 of the Service Manual) with an IEC Power in plug and switched on there is 245v AC from the mains but no DC reading across Connector CX102. It must rely on the 'cage' of pcb's being in place in order to work. Michael UK

 

[Michael Studio1]

Maybe there's a way to circumnavigate the power switching solenoid in order to activate the power supply on a temporary basis? Michael, East Sussex.

 

[Michael Studio1]

When you say: "This should be readily separable and still be 'connectible' to the main unit" what do you envisage as the method. They are certainly 'seperable' but getting the PSU powered in order to test it is the 'problem' - and how to do this is the question. Do you have a suggestion, please? Michael

 

[73's de Edd]

Sir Michael Studio1 . . . . .


Just confirming that I have the right manual, are both your manuals page 42 and the Adobe page being 42 and that page content being relevant to the main power supply and the side of the cabinets, small SMPS that is mounted vertically in the unit, just to the right of the HUGE linear power supply transformer.
AND, I also concur, on the manuals TOTAL page count.

On my referencing it is showing the sole output from the Switch Mode supply is being 5 VDC at a hefty amperage as the +5-----Minus 5-----3.3-----1.2------1.1 are being derived from it also.


The + and - 8 VDC supplies are being derived from the linear supply portion. as well as your voltages for the display.

When I have the same access problems, since we are not working with 200 Mhz RF, I also use Cat 5 sourced individual wires that are being ran out from soldered to test points of interest, and laced thru holes in a piece of cardboard and the specific wires ends denoted on it.
THEY want you to buy THEIR wiring jig / adapter for the possible one time repair on this unit .

Talk to me . . . .

73's de Edd

 

[Michael Studio1]

Sir Michael Studio1 . . . . .


Just confirming that I have the right manual, are both your manuals page 42 and the Adobe page being 42 and that page content being relevant to the main power supply and the side of the cabinets, small SMPS that is mounted vertically in the unit, just to the right of the HUGE linear power supply transformer.
AND, I also concur, on the manuals TOTAL page count.

On my referencing it is showing the sole output from the Switch Mode supply is being 5 VDC at a hefty amperage as the +5-----Minus 5-----3.3-----1.2------1.1 are being derived from it also.


The + and - 8 VDC supplies are being derived from the linear supply portion. as well as your voltages for the display.

When I have the same access problems, since we are not working with 200 Mhz RF, I also use Cat 5 sourced individual wires that are being ran out from soldered to test points of interest, and laced thru holes in a piece of cardboard and the specific wires ends denoted on it.
THEY want you to buy THEIR wiring jig / adapter for the possible one time repair on this unit .

Talk to me . . . .

73's de Edd

Hello 73's de EDD - Michael here. Thanks for taking interest in this somewhat tricky AVR-1912 E2/EA repair and Thanks for your interesting Post.
Re the Manual. This is the Service Manual for the Denon AVR-1912 E2/EA. Ver 6. Check that Page, say, 111 is SCHEMATIC DIAGRAMS (6/26) ?? ok ?? If so, then here are my current thoughts: Try as I might I cannot figure out what power rails are appearing at the connector blocks on the SMPS B'D (page 109 on AVR-1912 E2/EA model) for it seems to me that the SMPS_B'D only supplies Standby Power. The main Xfmr is mounted on the main chassis and isn't part of the SMPS B'D. It has secondary windings of A/C (of course) supplying the REG_CNT (p.110) through CP102 & CP104, the SPEAKER B'D (p.108) through CP1, and the FRONT UNIT (p.130) through a 'spaced' 7-pin connector CP101. Regarding the REG_CNT (p.110), there are five Full Wave Rectifier Ccts. on this pcb which is attached by Edge Connectors to the REGULATOR B'D.. Still (on p,110) I have a 'TaggedTestTail' on CN101 (pin1)+8V. This reads +10.78V. Next, (on p.111) 'SIDE CONNECTOR' a 'TaggedTestTail' on CN14 (pin14) +8V. This reads +4.589V. My readings are taken with a UNI-T UT61E dvm. The Positive probe of this I have extended with a sharpened 4" length of 0.041" Bass Piano wire, sheathed in some red insulator covering (from some discarded mains cable) and attached to the real proble by one of those cable connectors which use a pair of 'grub' screws. I like your 'lacing through holes in a piece of card' idea. I was thinking along the same lines but only have two 'TTT's so far.
As to the 'Wiring Jig' Nr. 8U-110084S I applied to Denon UK (Peterborough) who refused to sell this to me on the basis I am not a registered repairing company. On applying to a different Denon UK repairer (London) they told me they didn't have a set in stock but it is possible to repair it without this 'Jig for Servicing'.

 

[Michael Studio1]

Page 42 of my Service Manual shows, on the Top Right: VCC BLOCK DIAGRAM Michael

 

[Michael Studio1]

Page 42 of my Service Manual shows, on the Top Right: VCC BLOCK DIAGRAM Michael

I would like to work with someone on this AVR-1912 E2/EA. The voltages are wrong (according to my dvm readings) The +8V.rail is suspect so I would like to confer readings. I am soldering 'Tagged Test Tails' to various Connector Blocks in order to check their voltages with the PCB's reassembled. Can anyone help me, PLEASE?

 

[Michael Studio1]

Sir Michael Studio1 . . . . .


Just confirming that I have the right manual, are both your manuals page 42 and the Adobe page being 42 and that page content being relevant to the main power supply and the side of the cabinets, small SMPS that is mounted vertically in the unit, just to the right of the HUGE linear power supply transformer.
AND, I also concur, on the manuals TOTAL page count.

On my referencing it is showing the sole output from the Switch Mode supply is being 5 VDC at a hefty amperage as the +5-----Minus 5-----3.3-----1.2------1.1 are being derived from it also.


The + and - 8 VDC supplies are being derived from the linear supply portion. as well as your voltages for the display.

When I have the same access problems, since we are not working with 200 Mhz RF, I also use Cat 5 sourced individual wires that are being ran out from soldered to test points of interest, and laced thru holes in a piece of cardboard and the specific wires ends denoted on it.
THEY want you to buy THEIR wiring jig / adapter for the possible one time repair on this unit .

Talk to me . . . .
Hello 73's de Edd - Since we seem to be on the same 'wavelength' I am trying to 'Talk to you' Maybe I am not tackling this Forum correctly - pressing the wrong button - posting in the wrong way or area. With the Denon AVR-1912 E2/AE on the lab bench and rarin' to go, please 'Talk to me . . .
73's de Edd

 

[Michael Studio1]

I seem to be having some difficulty in making contact with anyone on this Forum who would be interested in helping to find the problems in this Denon AVR-1912 E2/EA where the +8V. rails are anything but +8V. I have soldered short lengths of insulated Jumper-wire to various contacts on PCB's so the AVR can be switched on and test voltages taken.
Please Talk to me . . . Michael.

 

[kellys_eye]

Post the schematic of the supply circuit.

 

[Michael Studio1]

OK, Kelly's Eye. Thanks for your reply. I'm not sure whether, having printed it all out and made two pocket ring-binder Manuals of it, that the pdf is still on my laptop. I like to pore over hard copy . . . Michael

 

[Michael Studio1]

Post the schematic of the supply circuit.

Hello Kelly's Eye. I find I haven't the pdf still for the Denon AVR-1912 E2/EA - BUT - I did find it on-line again at this address:
https://www.scribd.com/document/239888631/Denon-AVR-1912.

I checked it was the same as mine - and it is. Page 2 gives the list of contents, I am looking at page:109 [SMPS B'D]. I could be wrong, but I find there seem to be frequent anomalies in the numbering of the contacts in the edge connectors - where contact 1 is at one end of the Connector on one Board, and at the other end of the connector in the corresponding board. So pin1 in a 'CN' connector with 23 pins may turn out to be pin 23 in its associated 'CP' connector. Happily, though, every connector block has all pins annotated on its PCB. Whew!
I do hope that downloading this pdf and working from it does not make anything difficult for you - for I cannot think of a way to send you individual Cct. Diags. Looking forward to your response!! Michael

 

[Tha fios agaibh]

I found this, but it's hard to see. https://www.manualslib.com/manual/986184/Denon-Avr-1912e3.html?page=109#manual

 

[Michael Studio1]

View attachment 38893 I found this, but it's hard to see. https://www.manualslib.com/manual/986184/Denon-Avr-1912e3.html?page=109#manual

Yes, this is the Cct. Diag. given on page 109 in the AVR Service Manual quoted above, which is downloadable from that Link and is the one I am using. I had problems on this SMPS B'D when CX102 was found un-soldered and able to be pushed further through the PCB resulting in the tearing away of the foil connection to two jumpers on the component side. Having appreciated this I re-soldered CX102 and included a new jumper on the foil side between the CX102 connector and the horizontal jumper which runs under the Fuse 101. I am holding this SMPS B'D right now. Michael

 

[Michael Studio1]

Yes, this is the Cct. Diag. given on page 109 in the AVR Service Manual quoted above, which is downloadable from that Link and is the one I am using. I had problems on this SMPS B'D when CX102 was found un-soldered and able to be pushed further through the PCB resulting in the tearing away of the foil connection to two jumpers on the component side. Having appreciated this I re-soldered CX102 and included a new jumper on the foil side between the CX102 connector and the horizontal jumper which runs under the Fuse 101. I am holding this SMPS B'D right now. Michael

I agree these Cct.Diags. are hard to see - particularly the Component Nos. and pin Nos. This is why I am wearing one of those magnifier head bands with three lens units. (I also have cataracts which makes this a bit more tedious) Michael

 

[Tha fios agaibh]

I suggest posting a few close up photos(both sides) to get a better idea of the smps circuit. A picture is worth a thousand words. Perhaps a few hundred from a fuzzy one. Between that and what can be physically seen, an accurate schematic should come to life.

It's a good sign that you peaked the interest of 73's de Edd. I'd be willing to bet he'll have a brilliant post complete with illustration before I could start to understand this circuit.

 

[Michael Studio1]

I suggest posting a few close up photos(both sides) to get a better idea of the smps circuit. A picture is worth a thousand words. Perhaps a few hundred from a fuzzy one. Between that and what can be physically seen, an accurate schematic should come to life.

It's a good sign that you peaked the interest of 73's de Edd. I'd be willing to bet he'll have a brilliant post complete with illustration before I could start to understand this circuit.

OK, "Tha fios " I'll get out my ancient Sony DSC-W270 and see if I can Upload a couple of shots of my SMPS_B'D. I'm assuming (not having done this here before) I 'Upload a File' to do that?