Denon AVR-1912 E2/EA

[Michael Studio1]

This intermittent business worries me. I saw on some forum somebody with a Denon had to plug/unplug a connection 3 or 4 times with a clean after every unplug before it started connecting reliably. Could a bad connection somewhere be triggering a protection circuit, of which the Denon apparently has plenty.
And I still think plugging it into a TV will help.

My 2c

Thanks for your 2c. worth, Dries. The only T/v I have in the Lab is an Analog 13" Daewoo with a SKART socket and Analog Antenna IN socket. From time-to-time it gets plugged into our CCTV cameras. As for the intermittent in the 'plocketry' there are so many connectors. You know these pcb mounted zig-zag male and female connectors? That's what there is on these pcb's. It's the loss of the 5V. rail somewhere that is so bothersome. Michael Studio1 UK 11:36BST 18-05-2018

 

[Tha fios agaibh]

I agree, a bad connection could be causing intermittent problems.
Not a bad idea to clean the plug/receptacle connections with alcohol or contact cleaner. Like I said before, you found one bad ribbon cable already, so there's a good chance there's another one somewhere else.
I dont remember where you got the replacement, but perhaps an entire kit is available?

So, you don't have power on either sides of the fuses? Looking like the transformer or connections from it.
..The saga continues.

 

[Michael Studio1]

I agree, a bad connection could be causing intermittent problems.
Not a bad idea to clean the plug/receptacle connections with alcohol or contact cleaner. Like I said before, you found one bad ribbon cable already, so there's a good chance there's another one somewhere else.
I dont remember where you got the replacement, but perhaps an entire kit is available?

So, you don't have power on either sides of the fuses? Looking like the transformer or connections from it.
..The saga continues.

Indeed, John - and what a saga! Right now I have all the pcb's out again and am going to check them for continuity - and see where the 5V. supply comes from. Memory tells me 73's de Edd told me the answer to that a few months ago - so I must back-track this saga to find out. I was beginning to suspect TR16 on page117/J7 in the SWM5V which is what the 5V. rail is called in the interconnecting schematics layout: viz. page117/N6 - but before I could establish anything power was lost. Now I cannot continue and shall leave this thought with you: Isn't it funny that cats have holes in their fur just where their eyes are! Michael Studio1 UK 21:10BST 18-05-2018

 

[bushtech]

When you get back to TR16/TR17: pg 105/196. There are two connectors on the left hand side of board. Look to the right in line with the top of the top (bigger) connector. Second set of components along that line is TR16/TR17

 

[Tha fios agaibh]

I'm not sure, but it looks like TR16 must first have standby power at its emitter and TR17 base must have a current from cpu power in order to pass SWM5V.

Getting to the wee hours of the morning here. I'm getting too tired to follow along.

Btw, I'm always amazed at how cats can curl their front paws all the way back under them and go to sleep.

 

[Michael Studio1]

When you get back to TR16/TR17: pg 105/196. There are two connectors on the left hand side of board. Look to the right in line with the top of the top (bigger) connector. Second set of components along that line is TR16/TR17

Thanks, Dries, I found that. All the pcb's are currently apart. I propose checking the continuity and solder joints at the connectors. Quite some job I shall not do in a hurry. The only connection I am loath to take apart is the CX4 FFC ribbon into the top of the HDMI_B'D. It's currently OK (no pun intended) Michael Studio1 UK 07:10BST 19-05-2018

 

[Michael Studio1]

I'm not sure, but it looks like TR16 must first have standby power at its emitter and TR17 base must have a current from cpu power in order to pass SWM5V.

Getting to the wee hours of the morning here. I'm getting too tired to follow along.

Btw, I'm always amazed at how cats can curl their front paws all the way back under them and go to sleep.

Thanks, John. I see your point re: standby power. So I must check at CX101 (page109/N6) a ribbon cable from the SMPS_B'D where it connects to the HMDI_B'D as CX1. BTW, it was on the SMPS_B'D where the pin of CX102 was loose (causing all those sparks) It seems, on closer inspection, that I didn't get the loose pin fully through the hole in the pcb and it's sticking out a bit on the FOIL_SIDE of that pcb. I must heat it up again and push it right through to match the other pin. Never know! But doubt it's connected with the problem for the AVR power would have simply turned off. And it didn't. Michael Studio1 UK 07:28BST 19-05-2018 < I make these dates so I can get them in my mind as to when it was - in the great scheme of things! M.

 

[Michael Studio1]

And this is what I got from Kelly's Eye in January:

 

[Michael Studio1]

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.

73's de Edd makes his appearance on Page 2 of this discussion. I must read these replies diligently. Michael Studio1 UK 10:09BST 19-05-2018

 

[Michael Studio1]

I have been attempting to test TR16 in Cct. but the pins are so close together and need a triple-probe to do so that the results I am getting are not really reliable. Sometimes it says two pins are shorted and sometimes it says it's a Power Diode - so unless I can figure out a way to do a triple probe . . . I tried sticking three pins through a piece of an eraser, insulating the heads and using the hook-clamp probes of the Peak DCA55 meter to connect to the pin heads - but it was very dodgy and unreliable to get a reading. What do they say? Necessity being the Mother of Invention? I must try harder with my inventiveness! Unlike the Capacitor ESR70 meter, the transistor meter isn't intended for in-Cct testing. Michael Studio1 UK 20:42BST 21-05-2018

 

[Tha fios agaibh]

I have been attempting to test TR16 in Cct. but the pins are so close together and need a triple-probe to do so

Why?
Just measure emitter to ground voltage to see if you have 5v + (standby power). Then measure base to ground. This should be about 0.7v less than the emitter (4.3v or less) in order to forward bias it.
If there's a negative current on TR16 base, it should be switching on and sending voltage through to the collector.

 

[Michael Studio1]

Why?
Just measure emitter to ground voltage to see if you have 5v + (standby power). Then measure base to ground. This should be about 0.7v less than the emitter (4.3v or less) in order to forward bias it.
If there's a negative current on TR16 base, it should be switching on and sending voltage through to the collector.

Thanks, John. That's really helpful suggestion. The AVR is still in bits - I shall either find a place for probing for the Voltages or attach other Test Tails - but this time of CatE stuff. I was looking on line to see if the 2SA1954 is available, just in case it was a casualty from the earlier event, but I can't see an SM variety. Maybe there's a pairing with an RT1N41C (TR17) like I found with that Darlington Pair? Will follow your test suggestion first though. Thanks. Michael Studio1 UK 08:52BST 22-05-2108

 

[Michael Studio1]

the 'Why? - is because of the access to the underside of the HDMI_B'D when in situ. The TR16 is Very Small and probing is going to be very difficult under there in the 'stack' of pcb's. SO I was looking for a way out of this with the Peak DCA55 test meter. I shall go for test-tails I think (if I can find no other way). Michael

 

[kellys_eye]

Just curious.....

472 replies and 24 pages.....

is this thing fixed yet?

 

[Michael Studio1]

Just curious.....

472 replies and 24 pages.....

is this thing fixed yet?

Here's the answer to your curiosity: NO. Due to the various difficulties and access to test points with the AVR assembled, I am having to continually take it apart (the way it is right now) to find out where the problems lie. As you know, this conglomeration of inter-connected pcb's cannot be turned ON unless they are all connected together. That's the real stumbling block. There is, on Page 43 of the AVR Service Manual, reference to a 'Service Jig' - for testing with all pcb's connected. Denon initially refused to sell me this Jig, then eventually relented and said it's available for some horrific price - several hundred Pounds GBP - so I came up with the idea of 'Tagged Test Tails' to overcome the problem. I discovered that 73's de Edd also had this idea. That is why this repair has gone on for so long - that and various intermittent problems which keep coming up like: suddenly no 5V. supply to the HDMI_B'D. etc. The Saga continues - 'cos I'm trying to not give up! It's the ultimate challenge! well, nearly! Michael Studio1 UK 11:37BST 22-05-2018

 

[kellys_eye]

Here's the answer to your curiosity: NO.

Thanks for the update.

I recall your original issues with getting at the boards - I'd have knocked up some extenders of my own by now (being as how I'm a cheapskate!) - the frustration would have got the better of me.

 

[Michael Studio1]

Thanks for the update.

I recall your original issues with getting at the boards - I'd have knocked up some extenders of my own by now (being as how I'm a cheapskate!) - the frustration would have got the better of me.

Yes - I too have been cogitating along those lines. Trouble is: getting the correct plocketry. I have spent quite a bit of time on this issue looking for those staggered connectors - without result. So I'm sticking with the 'tagged test tags'. After all, I'm retired and have nothing else to do - except water the garden, feed the birds and wash the car - which I don't drive. Given that up. Got too old. Reactions dodgy. And today's my eldest daughters' birthday - she's 58 with two at University. Michael Studio1 UK 15:50BST 22-05-2018

 

[Michael Studio1]

Poor old you . . . (don't worry, I'm always 'thinking to myself' i.e. I don't talk to myself) Today I have taken the plunge of attaching some Cat 5E conductors to the pins of TR16 - it's so tiny!!. I've probably fried it in the process with the soldering iron. If so I shall have a good time removing and replacing that 2SA1945 with the 858D hot-air soldering wand. The AVR turns on and stays on even after all that time in bits on the bench - so maybe that's a good sign. But now I'm finished for the day and have turned everything off and shut up the Lab. Michael Studio1 UK 20:47BST 22-05-2018

 

[Tha fios agaibh]

She's quite the conundrum, isn't she?
I must confess that I keep forgetting how invasive it is to access test points. It's one thing looking at the schematic, but another working under such restraints.

Soldering long leads to tiny smd components is not practical and could possibly cause other problems.

Yes, you need to find where your loosing the 5v rail, but perhaps we can find a more feasible place to probe for it.

Problem is, I can physicaly see what you can reach and how/where that node is on the schematic.

Perhaps some close up photos would help?

 

[Michael Studio1]

Here are the results from TR16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Emitter to GND = +8.789V. Base to GND = +8.066V, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Michael Studio1 UK 06:29BST 23-05-2018