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Denon POA 6600 Thread

Hey Bratwurst, have you tried checking for low level sound output while the amp is still on DBT?
I may have missed it, would be good to confirm if the problem is isolated to the bias generation circuit or there's no sound out.

I prefer to keep the original ICs if they haven't failed (while troubleshooting), just to avoid further complication. Is IC501 still the original part?
I should have spare M5218s here I can post out if you think it'd help. I'm yet to see one fail myself.
 
theophile said:
I was almost going to ask the mods to merge this thread into "Fart Proudly"*

*Now sponsored by All Bran in association with Metamucil. Association is mandatory due to starting with 'Ass'.
Click to expand...
Well, the terrible thing as that I seem to have lost my ability to Fart on command. In fact sometimes a whole day goes by without passing any serious wind. I might have to go to some kind of therapy or something.

:beerchug:,
James
 
Last edited:
zaibatsu said:
Hey Bratwurst, have you tried checking for low level sound output while the amp is still on DBT?
I may have missed it, would be good to confirm if the problem is isolated to the bias generation circuit or there's no sound out.

I prefer to keep the original ICs if they haven't failed (while troubleshooting), just to avoid further complication. Is IC501 still the original part?
I should have spare M5218s here I can post out if you think it'd help. I'm yet to see one fail myself.
Click to expand...
I have tried the original NJM082BD, a TL082CP and a OPA1656AIDR, at this point both of the original op-amps are installed. I don't think that the problem is with an op-amp. I think that I am not getting enough minus voltage into that section because I did something wrong.

But hey guys, I won't be posting any voltage measurements today. Because I didn't get my Ass in gear. Or you could say that I looked at the amp a few times, gave it the evil eye, and walked away. At some point in time I learned not to work on an amp when I am pissed off at it. Sometimes you just have to walk away and drink beer.

:beerchug:,
James
 
OK. First, no, I am not taking the amp off of the DBT right now. Not until I am more certain that I have not done something seriously wrong.
So all of these voltages will obviously be reading low.

IC501:
1: +1.29v
2: -0-004v
3: -0.001v
4: -15.01v
5: +0.001v
6: -13.73v
7: -13.73v
8: +15.02v

IC502:
1: +0.009v
2: -0.000v
3: -0.001v
4: -15.09v
5: -0.001v
6: -0.001v
7: +0.007v
8: +15.05v

TR551:
E: +0.76v
C: +1.104v
B. +0.731v

D509: I just realized that I skipped D509, going to have to go back and check it.

Note that at this time I have the idle current trimmer turned all the way down.

:beerchug:,
James
 
Last edited:
R537: +15.08v / +1.102v
R539: +1.102v / +1.292v
C521: +1.102v / +1.292v

R540: -15.15v / -0.588v
R538: +1.295v / -0.588v
C522: +1.292v / -0.588v

R541: +1.102v / +0.068v
C523: (plus lead) +0.732v / (minus lead) +0.068v
R542: +1.102v / +0.732v
 
C530 & R553: +1.102v / +0.772v
C531 & R554: -0.584v / -0.582v

TR507:
E: +0.0629v
C: +75.2v
B: +0.046v

TR508:
E: -0.623v
C: -75.2v
B: -0.048v

R529: +42.0v / +74.9v
R531: +42.0v / +15.11v

R530: -42.0v / -15.17v
R532: -42.1v / -75.1v

:beerchug:,
James

edit: I had the pin orientation of TR507 and measurements backwards, corrected.
 
Last edited:
Soundscape said:
ABC
always
be chasing
voltage

cheers bitch
:beerchug:
Click to expand...
Doing that.
This part is starting to look...interesting?

TR505:
E: +74.1v
C: +0.626v
B: +73.5v
TR506:
E: -74.7v
C: -0.620v
B: -74.1v

TR504:
E: +74.0v
C: +0.576v
B: +73.5v

TR523:
E: +0.571v
C: -73.6v
B: 0.000v

TR:500:
D: +12.63v
G: 0.000v
S: +0.253v
TR:501:
D: +12.56v
G: -0.003v
S: +0.253v

TR502/TR503: I could not safely get at E or C on these. B is +12.63 on both.

D505:
C: -74.5v
A: -73.7v

Looks like D505 is shorted. TR504 to 506 don't look good.
I am going to drop the board now and check those.

Note that I had the amp turned on on the mains (off of the DBT) for about 15 minutes before my vacation.

:beerchug:,
James
 
On a completely different note, separate from my problems, I made a large Mouser order last week.

Included were some 1µF/100v elcos. The Kemet that I wanted are on back order till Sept, so I also ordered some Rubycon YXM series, 105°, 10,000 hour, low impedance.
https://www.mouser.de/ProductDetail...snSoBL7hffg==&countryCode=DE&currencyCode=EUR
And some Bourns 10k 25 turn trim pots.
https://www.mouser.de/ProductDetail/Bourns/3296Y-1-103LF?qs=V3Em1enZyNPGF2%2BnCaKTKw==

As well as a selection of op-amps. OPA1602, 1612, 1632, 1642, as well as some more 2132 and 2134.
 
First mistake found:
Because of misreading C526 and 528 on the board I replaced them with their values incorrect, backwards.
C526 should be 0.01µF, had a 0.1µF installed.
C528 should be 0.1µF, had a 0.01µF installed.
Corrected.

C524 and 525 now have some of those Rubycon 1µF/100v elcos installed.

TR504, 505 and 506 have been removed, tested and replaced. They were good.

All of the 50v 0.1µF and 0.01µF ceramic caps that I had installed have been replaced with 100v parts.

Completed an intensive inspection looking for solder bridges etc, no discrepancies found.
:beerchug:,
James
 
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On a completely different note, I saw a silver Denon DCD-2700 CD player (with remote) and a Visiton MHT12 planar tweeter on ebay today for very attractive prices and couldn't resist them.

:beerchug:,
James
 
Bratwurst7s said:
Doing that.
This part is starting to look...interesting?

TR505:
E: +74.1v
C: +0.626v
B: +73.5v
TR506:
E: -74.7v
C: -0.620v
B: -74.1v

TR504:
E: +74.0v
C: +0.576v
B: +73.5v

TR523:
E: +0.571v
C: -73.6v
B: 0.000v

TR:500:
D: +12.63v
G: 0.000v
S: +0.253v
TR:501:
D: +12.56v
G: -0.003v
S: +0.253v

TR502/TR503: I could not safely get at E or C on these. B is +12.63 on both.

D505:
C: -74.5v
A: -73.7v

Looks like D505 is shorted. TR504 to 506 don't look good.
I am going to drop the board now and check those.
Click to expand...
I'll post a schematic for folks to compare the readings to it.

Screenshot_2024-06-11-23-42-52.png
 
I haven't compared all the readings with the SM but if it comes out of protection, and the DC at the speaker terminals is less than 100mV. I'd try and bias it at 4 or 5mV and play some music. All while on the DBT.
 
Soundscape said:
I haven't compared all the readings with the SM but if it comes out of protection, and the DC at the speaker terminals is less than 100mV. I'd try and bias it at 4 or 5mV and play some music. All while on the DBT.
Click to expand...
Can't set the idle current at all.

Having + and - 75v on the BASE of 3 transistors has me stumped at the moment. I can't find the path where that is happening. And those 3 transistors are running hotter than a 2 Dollar pistol, and that on the DBT.

I took a break from it today and dealt with easy stuff like financial matters and deciding on which Rum to sip on.

:beerchug:,
James
 
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