Denon AVR-1912 E2/EA

[73's de Edd]

Sir Michael . . . . .

O.K. here I have the two power supplies initial prep work, with its added annotations of your initially mentioned areas of testing.

You say . . . .

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.

No problem on that high of a voltage level as that is actually being the initial RAW DC supply voltage from which the + 8 VDC is to be derived from AFTER it comes out from the IC106 . . . a 7808 linear regulator.


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.

Now that present voltage IS supposed to be a now regulated + 8VDC level and not the +4.589V VDC which you are reading.
That now poses the question, is that a faulty IC106 regulator or is it from loading downstream upon this supply line pulling it down to this present reduced output level?

You may notice some skips in your manual, relevant to schematic pages, this one below actually shows the linear supply's portions massive transformer, and its circuitry as well as the SMPS.

You can see that the SMPS feeds a . . . whole pitshot . . . . of minor supplies that are further divided down and derived from its basic / sole 5VDC output.
I suggest that only the +8VDC regulator is left working and having the feeds to the other boards*** disconnected and then see if the +8VDC is up to full voltage and then start adding on the other branched out supplies from this source to see which one is pulling it down.
***Connector CP13A Pin 7
*** Connector CP5 Pins 11 & 12
*** Connector CN403 Pins 9 & 10

Thasssssssit . . .for now . . . .

POWER SUPPLIES BASIC SCHEMATIC . . .
Touch points . . .
As is seen after the unit has AC power from the wall outlet, this units SWITCH MODE power supply is active 48 hrs per day, with its ~ +5VDC output.
Also it feeds the YELLOW box power relay to activate AC power to the upper linear supply transformer primary, IF there is a logic HI from the units uP to feed to the base of the relay driver transistor, located just below the relay.



73's de Edd

 

[Tha fios agaibh]

I'll 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?

Link about taking good photos
https://www.electronicspoint.com/resources/how-to-take-photos-of-circuit-boards.6/
Then, click on upload file, then select choose file and pick the location (path) of where you saved the photo.

 

[73's de Edd]

Sir Michael . . . . .

SUPPLY ROUTES RELATED WITH +8VDC SUPPLY. . . . . .



73's de Edd

 

[Michael Studio1]

Sir Michael . . . . .

O.K. here I have the two power supplies initial prep work, with its added annotations of your initially mentioned areas of testing.


73's de Edd
.....

Many thanks, 73's de Edd - you have given me a whole lot to check on. I have printed out your comments and shall take them into my Lab in order to work on your proposed 'TestTails' I shall then re-assemble the AVR, take readings from those new TestTails and report my findings. That is an interesting Cct. Diag. which you included - I'm not sure if it's part of the Service Manual which I downloaded, if so, what page is it on?, - Michael

 

[Michael Studio1]

Link about taking good photos
https://www.electronicspoint.com/resources/how-to-take-photos-of-circuit-boards.6/
Then, click on upload file, then select choose file and pick the location (path) of where you saved the photo.

Thank you very much for those instructions! I have taken two photos (component side and foil side) and hope they're good enough. Everything is a bit blurred to my eyes! I shall upload them tomorrow for I simply can't think straight at this time of night! Michael at 22:48 gmt

 

[Michael Studio1]

Sir Michael . . . . .

SUPPLY ROUTES RELATED WITH +8VDC SUPPLY. . . . . .

View attachment 38903

73's de Edd

Yes, and many thanks, 73's de Edd. This is the exact Cct. Diag. as on my copy of the Service Manual, page 111. So we're 'in sync' I will be attaching your suggestions to the PCB's tomorrow as my eyes don't see well this late! Michael 22:58 gmt

 

[Michael Studio1]

Here are the two photos of the Denon AVR-1912 E2/EA, SMPS B'D. (Service Manual page 109) I hope they are focussed. On DSC05054.JPG you will see the short black insulated jumper I installed between CX102 and the end of the component side jumper which goes horizontally beneath Fuse 101.

 

[Michael Studio1]

73's de Edd. 'Tis tomorrow already! The sun is shining and I'm in my Lab. attaching 'TaggedTestTails' as per your Post, Before I put Tails on 'SIDE_CNT B'D' at CP5 pins 11 & 12, I tested the value between these pins with my DVM and found there's a virtual short: 0.3 Ohms with a HoldPeak HP-9804. The B'D is NOT connected to any other B'D. Michael

 

[Tha fios agaibh]

pins 11 & 12, I tested the value between these pins with my DVM and found there's a virtual short

Suspicious, but did you first to do as 73's de edd says and see if the voltage comes back up by isolation? If it returns to 8v or higher with everything hook up except cp5, your likely on the right path.

 

[73's de Edd]

Sir Michael . . . . .

Consult my post #23 for referencing and you will see that from its origin at the CP13 connector pin 7 and then its routing thru the boards that I have highlighted in PINK, that the +8VDC supply line branches out / duplicates and uses redundant dual connections into / within :
CN14 at its pins 14&15
CP5 at its pins 11&12
and
CN403 at its pins 9&10

Thaaaaaaaaaasit . . . .
Keep diggin' . . .til finding that X, which marks the spot . . . . .

73's de Edd

 

[Michael Studio1]

Suspicious, but did you first to do as 73's de edd says and see if the voltage comes back up by isolation? If it returns to 8v or higher with everything hook up except cp5, your likely on the right path.

Thanks, Tha fios agaibh. for your timely comment, The answer is 'NO' - the reason is that I couldn't fathom how to achieve this 'isolation' - and really need help to do so. I find that any break in the circuitry of this AVR tends to cause the whole thing not to power up. Reading your question, though, you say: "with everything hook up except cp5" Do I assume that this isolation may be achieved by simply NOT connecting CP5? This is not possible, of course, for CP5 is part of the 'build' to make the 'cage' with the HDMI_B'D. The principle makes sense but the method is beyond me. That pair of contacts which are apparently shorting: (CP5, pins 11 & 12, Service Manual Page 111) are impossible to tell whether they should or should not be 'shorted' together as they are both intended to be +8V. and the other end, on the SIDE_CONNECTOR of that pair is CN403 pins 9 & 10.(both +8V.) There is a 'spur' from CP5 pin 12 which ends up at CP13A pin 7, marked +8V. also leading to CN14 at pins 14 & 15 - which pair appear to be shorted in the SIDE_CONNECTOR B'D. So I must look closely for solder debris causing this 'short' on the SIDE-CNT. for the Cct Diag certainly doe not indicate any connection between the two foils.
Of the three groups of 'TaggedTestTails' 73 de Edd proposed it was the final pair which gave the most aggro. I attempted to access the foil side of the 7 Channel AMP_B'D only to find it impossible and had to return it to status quo. The only real option open then was to remove the SPKR_B'D - which I have now done. There are two things (part from the two sheet metal screws) holding it in place, they are: a white plastic pillar, needing clamping together to allow its' extraction, and one sheet metal screw holding down: GBJ1006 - a 4 x pin semi-conductor component. This B'D also has those two vast 12,000 Mfd. caps - which I must discharge. Maybe I shall do this by testing for any residual Voltage with a DVM? Anyway, the SPKR_B'D is removed and I can attach the last two 'Tails'. Please excuse the apparent excess of verbiage! Michael

 

[Michael Studio1]

Continued: I have been attaching the 'Test Tails' you proposed, 73 de Edd, but have found a short between pins 11 & 12 of CP5. on the SIDE_CNT B'D. I am checking to see whether there is some clumsy soldering (on my part) or conductive debris.

Having now checked this and found nothing untoward is it possible that ALL seven events of +8V. are supposed to be connected together in the SIDE_CONT. B'D.??
I cannot follow your method of "isolation" and need help, please.

Michael

 

[Michael Studio1]

Sir Michael . . . . .

Consult my post #23 for referencing and you will see that from its origin at the CP13 connector pin 7 and then its routing thru the boards that I have highlighted in PINK, that the +8VDC supply line branches out / duplicates and uses redundant dual connections into / within :

73's de Edd

Many thanks, '73 de Edd for your 'personalised' Cct. Diag. showing the flow of the +8V. rail within the SIDE_CONNECTOR (Service Manual page 111) Very helpful.
One question: Starting from CN13A pin 7, (apart from supplying CP14, dualled pins 14 &15,) it crosses horizontally the two +8V. rails which join CN 403 pins 9 & 10 to CP5 pins 11 & 12. Where it crosses the first +8V. rail (from CN 403 pin 9 to CP5 pin 11), it terminates on the second +8V. which goes between CN403 pin 10 and CP5 pin 12. Does this +8V. rail make connection to both vertical +8V. rails? My reason for asking this is that all of those seven +8V. pins show they are connected together - according to my DVM. If it crosses one rail but makes no connection there's no accounting for my findings - except to conclude I have a faulty SIDE_CONNECTION B'D. Michael - UK

 

[Michael Studio1]

Sir Michael . . . . .

Consult my post #23 for referencing and you will see that from its origin at the CP13 connector pin 7 and then its routing thru the boards that I have highlighted in PINK, that the +8VDC supply line branches out / duplicates and uses redundant dual connections into / within :

73's de Edd

later . . Looking at your annotated Cct. Dwg. '73's de Edd' I am just seeing that the arrows you have added showing the +8V. divergent flow direction towards both CP5 and CN403 indicate there is indeed a connection to both +8V. vertical rails. Having crossed that hurdle I must now consult your massive power supply Diags before attempting re-assembly and Voltage testing at those 'Tails' This is rather like carpentry: 'Read twice and cut once' - I can only apologise for not seeing the full inference of your Posts! Michael UK

 

[Michael Studio1]

Sir Michael . . . . .

O.K. here I have the two power supplies initial prep work, with its added annotations of your initially mentioned areas of testing.



73's de Edd

Hello '73's de Edd. I am now consulting your Post 23 where you say:
You can see that the SMPS feeds a . . . whole pitshot . . . . of minor supplies that are further divided down and derived from its basic / sole 5VDC output.
I suggest that only the +8VDC regulator is left working and having the feeds to the other boards*** disconnected and then see if the +8VDC is up to full voltage and then start adding on the other branched out supplies from this source to see which one is pulling it down.
***Connector CP13A Pin 7
*** Connector CP5 Pins 11 & 12
*** Connector CN403 Pins 9 & 10
I would like to know how to physically implement your suggestions! How and where to disconnect the other boards*** This is totally New Ground for me!! and I wish to learn from you!
I have the SMPS B'D in front of me with its small yellow box marked 'CARLI' on the top placed next to and sharing two contacts with a strange, small, toroidal wound Xfmr? Michael - Friday 09:27 GMT.

 

[Tha fios agaibh]

Michael, I admire your tenacity in figuring it out. I don't have the schematic on hand to follow the specifics, but I'll offer some advice.
I think you understand what we're trying to achieve here. Trying to unload the power supply to find either a downstream excessive load or a problem in the smps itself.
If you have trouble removing the plugs supplying 8v to these loads, take each circuit board out and remove the first component inline of the +8 pin as to break continuity to that load.
This will isolate the board you removed.
Document the before voltage, and the after isolation voltage with each load you isolate. Such as board connected to cp5 (removed component in series with pin 12) before 4.5v, after X.Xv

 

[Michael Studio1]

Michael, I admire your tenacity in figuring it out. I don't have the schematic on hand to follow the specifics, but I'll offer some advice.
I think you understand what we're trying to achieve here. Trying to unload the power supply to find either a downstream excessive load or a problem in the smps itself.
If you have trouble removing the plugs supplying 8v to these loads, take each circuit board out and remove the first component inline of the +8 pin as to break continuity to that load.
This will isolate the board you removed.
Document the before voltage, and the after isolation voltage with each load you isolate. Such as board connected to cp5 (removed component in series with pin 12) before 4.5v, after X.Xv

Thanks for your helpful reply Tha fios agaibh. Right now the only boards in the chassis are the Front Panel, the 7 Channel Amp board and the Regulator and Regulator Control boards. This means I can closely examine all boards - including the SPKR_B'D and the SMPS_B'D. From the annotated Cct.Diag of the SIDE_B'D '73 de Edd posted which I seemed to be having problems with, it now seems clear that all events of the +8V. rail are electrically connected. Now I am to attempt this 'isolation' - and the route to doing this is, to me, far from clear! All PCB's in this AVR are held together by various sizes of Edge Connectors and so all instances of +8V. connections are included in those multi-way edge connectors and are inseparable from them. Therefore I am delighted with your suggestion of removing the first component inline of the +8V pin. I must first take on-board (mentally) the notion of what causes the AVR to shut down in panic - rather like a burglar faced with an alarm system!
As to CP5, this is connected to CN5 in the HDMI UNIT - Digital Control. According to the Cct.Diag. (page 129bnof the Service Manual) the first component on the +8V. rail from CN5 (pins 11 & 12) seems to be an in-line choke designated FB43 0/2012) There are 8 of these components in line - one for each of the Power+ Power- and STBY Power rails. Identifying them (and finding the right one) is a bit of a night-mare given the complexity of the HDMI_B'D !! Michael

 

[Tha fios agaibh]

...delighted with your suggestion of removing the first component inline of the +8V pin. I must first take on-board (mentally) the notion of what causes the AVR to shut down in panic -

Many ways to skin a cat. Or should I say isolate a cat?
It doesn't necessarily has to be the first component inline. (once it's rendered opencircuit the load will be gone)
If a component is difficult to remove, move on to the next accessible component. A practical technique is to just unsolder and lift one leg of a resistor.
You could remove any component inline but it leads to confusion the farther into the pcb you go.
If the chokes aren't too difficult or fragile, that may be your best plan of attack.

The AVR may be shutting down because the Smps is shut down. They are designed to operate under a specific load and often don't play nice when that load is out of what it's used to seeing.

 

[Michael Studio1]

Many ways to skin a cat. Or should I say isolate a cat?
It doesn't necessarily has to be the first component inline. (once it's rendered opencircuit the load will be gone)
If a component is difficult to remove, move on to the next accessible component. A practical technique is to just unsolder and lift one leg of a resistor.
You could remove any component inline but it leads to confusion the farther into the pcb you go.
If the chokes aren't too difficult or fragile, that may be your best plan of attack.

The AVR may be shutting down because the Smps is shut down. They are designed to operate under a specific load and often don't play nice when that load is out of what it's used to seeing.

Many thanks (about skinning - have to kill them first y'know?) - Well, there was another suggestion from 73's de Edd: "Maybe IC106 is faulty?" Who can tell? I've tested it with the Peak Atlas DCA-55 but it doesn't acknowledge it and looking at the specs of '3 terminal Positive Voltage Regulator', I am not surprised. It's one complex device packed into that small chassis mounted component. Its three legs drop down over the side of the Regulator B'D from their connecting points on that pcb and the IC is anchored by a s/m screw on the chassis. There are 6 of them one for each polarity of the three Power Ccts. That would be the easiest option - if it was the real problem. I cannot even find the choke-like components - they are depicted as a choke on the Cct.Diag. but I don't know what I'm looking for there.
As for the AVR shutting down - no, it isn't - but does if I were to open any Edge Connectors whilst it's on. So we don't need to examine that as a 'cause'. Maybe I should just re-assemble it (temporarily) See if it turns on and, if it does, check those Test Tails again? Michael

 

[Michael Studio1]

There was a point right at the beginning of this Power problem when there was terrific arcing in SMPS. I found the cause - the chassis-mounting power connector CX102 has its two legs through the SMPS pcb. The soldering had 'given' and done some damage to the foils side. I re-soldered it in place and added a jumper to one of its legs between 'it' and the end of a jumper where it is supposed to be. Whether this quite spectacular arc'ing had any effect on other components on the SMPS_B'D I don't know - but it's worthy of consideration, I think. Michael 3:31 GMT