Denon AVR-1912 E2/EA

[Michael Studio1]

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?

Hello John - I saw your reply after I had tested the Cat 5E connections to TR16 and posted my findings. That this AVR is a conundrum is putting it very mildly indeed. "Everything," as the Irish say "tends toward the maximum perversity" - Now That's a Law!! (Murphy's Law) But with those Voltage results, is TR16 still working? Michael Studio1 UK 06:39BST 23-05-2018

 

[Michael Studio1]

Turned on, the AVR is set to VAUX STEREO. The usual 700cps - Right Channel 500cps - Left Channel. These signal tones aren't even arriving from the Input. No sign at CX4 (ribbon cable) pins 6 and 8 just a loud Hum-m-m
Michael Studio1 UK 06:55

 

[Michael Studio1]

Checking the Voltages against AGND showed +8.16V at CN3 pin6 and -7.820V at CN3 pin7. The Voltages at TR16 (again with AGND) show: Emitter to GND = +8.789V. and Base to GND = +8.066V. The HUM-m-m-m-m was induced by my sheer stupidity (what's new?) I had NOT CONNECTED THE AUDIO AMP GND CLIP!!! Now I am tracing the L & R Signals through to IC30 pin1 & pin2. Yet still no Output at the default FR and FL. Progress!! Michael Studio1 UK 11:55BST 23-05-2018

 

[bushtech]

Keep at it!
Waiting for that Eureka moment

 

[Michael Studio1]

Keep at it!
Waiting for that Eureka moment

You and me both!. But at last I have both signal tones through to the ADC (IC30) Nothing from the FR & FL which is the default output. Michael Studio1 UK

 

[bushtech]

Have you checked voltages on the IC, pins 6 & 7 Va and Vd?

 

[Michael Studio1]

Have you checked voltages on the IC, pins 6 & 7 Va and Vd?

Thanks for the suggestion, Dries, I have been doing the washing and hanging it out in the Sussex sunshine! Now I will get back on the case. I have first printed pp.2 & 3 of AK5358A so I can see what to expect. OK - I should see VA 4.5 - 5.5V on pin6 (analog) and 2.7 - 5.5V on pin7 (digital). I see on page126/B5 the DA+5V power rail is being shared by IC27,IC29,IC30 and IC33 so I had better check that first against AGND. IC30 pins6&7 are joined together with pins14&15. I get a reading on the DVM of 5.119V. on IC30 pin6. May I take it all other sharing IC's will be the same? If so I dare say this is where my pocket-size Oscilloscope will come in useful - for tracking the IC30 digital output (pin9) MIchael Studio1 UK 14:51BST 23-05-2018

 

[Tha fios agaibh]

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

(Looking at Page 117)
So, Tr16 isn't getting turned on. It should have 6.6v at its base when Tr17 is switched on via CPU power. So CPU power is a requirement to get SWM3.3 and SWM5v.

 

[Michael Studio1]

(Looking at Page 117)
So, Tr16 isn't getting turned on. It should have 6.6v at its base when Tr17 is switched on via CPU power. So CPU power is a requirement to get SWM3.3 and SWM5v.

Thanks John for this information! Now that's the sort of conclusion I cannot come to - not understanding the 'why's and wherefores' which govern these things. I had hoped to 'get away' with soldering on those 'tails' (which made it possible to measure the TR16 Voltages) but by doing so do you think I have 'fried' that TR16 which will now have to be replaced? I had the feeling TR16 was already dead. I wonder if these 2SA1954 are available if this is the case. If so I shall have to fire up the 858D hot-air soldering machine. Michael Studio1 UK 22:20BST 23-05-2018

 

[Michael Studio1]

I shall have to look at this tomorrow - let's hope the CPU isn't fried as well! Michael Studio1

 

[Tha fios agaibh]

by doing so do you think I have 'fried' that TR16 which will now have to be replaced? I had the feeling TR16 was already dead.

We need to try to be methodical here.
Lets not assume anything is fried without first proving it.
If you don't have SWM3.3 nor SWM5v let's first look for CPU power (that turns on these supplies)page117.

If you have voltage on one supply but not the other, then a Tr probably is fried.

The reason I caution about soldering many long dangling leads to fragile components, is it can easily short something out, or could potentially cause circuit damage by introducing unwanted induction (noise/transient voltage. etc). to the circuit.

 

[Tha fios agaibh]

"CPU power" originates at pin 28 of IC41 microcontroller on page 128. I have no idea what conditions are necessary to turn on this output, but I would do whatever is necessary to get a monitor hooked up asap.

The onscreen menus should help you figure out what's going on, at least on the software side of the road.

 

[Michael Studio1]

We need to try to be methodical here.
Lets not assume anything is fried without first proving it.
If you don't have SWM3.3 nor SWM5v let's first look for CPU power (that turns on these supplies)page117.

If you have voltage on one supply but not the other, then a Tr probably is fried.

The reason I caution about soldering many long dangling leads to fragile components, is it can easily short something out, or could potentially cause circuit damage by introducing unwanted induction (noise/transient voltage. etc). to the circuit.

Thanks for your caution, John. I always terminate these dangling leads in one of those multi-way terminal strips - they come in lengths of 12 screw terminals which can be cut for the required number of test tails to be terminated - in the case of TR16, that is 3 - Base, Emitter, Collector. So these pcb's are not exactly festooned with with groups of 'test tails' all terminated in insulating terminal blocks and each tail tagged with source like 'CN101 pin5 AGND' etc. I also agree re: not 'assuming' anything - I'm just 'suspicious' of things (like that TR16). Michael

 

[Tha fios agaibh]

Thanks for your caution, John. I always terminate these dangling leads in one of those multi-way terminal strips - they come in lengths of 12 screw terminals which can be cut for the required number of test tails to be terminated - in the case of TR16, that is 3 - Base, Emitter, Collector. So these pcb's are not exactly festooned with with groups of 'test tails' all terminated in insulating terminal blocks and each tail tagged with source like 'CN101 pin5 AGND' etc. I also agree re: not 'assuming' anything - I'm just 'suspicious' of things (like that TR16). Michael

That's good that your cautious about terminating your test leads.
Why are you suspicious about TR16? Have you verified voltage for CPU power and SWM3.3 but SWM5v is not working?

 

[Michael Studio1]

"CPU power" originates at pin 28 of IC41 microcontroller on page 128. I have no idea what conditions are necessary to turn on this output, but I would do whatever is necessary to get a monitor hooked up asap.

The onscreen menus should help you figure out what's going on, at least on the software side of the road.

Thanks also for this, John. IC41 pin128 CPU POWER page128/G6 - This, and 11 others, goes TO D.SUPPLY. as shown on this page at N3-4. They're a bit sloppy on the production of this Service Manual - no proof-reader I guess. When you say "get a monitor hooked up asap." you mean a monitor speaker? and I'll look for a testing point to check the output from pin128 of IC41. By 'onscreen menus' do you mean what shows up on the screen on the front of the AVR? I know that may be obvious, but I've not been monitoring this - other than to check whether the AVR is still powered up - so I'm not sure what it can tell me. Michael Studio1 UK 08:51BST 24-05-2018

 

[Michael Studio1]

That's good that your cautious about terminating your test leads.
Why are you suspicious about TR16? Have you verified voltage for CPU power and SWM3.3 but SWM5v is not working?

Gosh! I didn't expect a reply so soon, John. I'm extremely grateful to you for the studied replies you give - which I try to follow. Please continue!! I'm just about to power up the AVR and find a test point for IC41 pin128. I must also find a test point for the SWM3.3 and SWM5V. Michael Studio1 UK 08:56BST 24-05-2018

 

[Michael Studio1]

IC41 pin 128 reads 6.149V. at that pin. I shall now look for
SWM3.3 and SWM5V. Michael Studio1 UK 09:18BST 24-05-2018

 

[Michael Studio1]

Test point on CN5 pin17 (SWM3.3V) actual = 6.86V. Test point on CN5 pin18 (SWM5V(MX)) actual = 8.779V.
Michael Studio1 UK

 

[Michael Studio1]

I can't say really why I was suspicious of TR16 - I couldn't get at its contacts to measure B/E/C - so I then attached the test leads. That TR16 is so tiny and I was therefore very suspicious about what my application of a HOT soldering iron on those tiny pins would have on the Transistor itself. Now I have verified the voltage at IC41 pin128 as 6.194V. and the SWM's as above (which are both way too high) where, please, do I go from here? Michael

 

[Michael Studio1]

I have removed those 'tails' from TR16, turned on the AVR and checked the Voltages at IC30 - pin6 and pin7 = 5.118V. These being really accessible on top of the HDMI_B'D. Michael Studio1 UK 11:01BST 24-05-2018