Sony CDP-222ESD tweaking

[carlosfm]

Originally posted by guytou
Ah , don't forget to cut the path to the analogue stage .(generally there is a serie resistor between the DAC and the first opamp)

Are you sure?

[Scorpio(DDMF)!]

Originally posted by rfbrw



Not sure what procedure you are referring to but if you mean passive
i/v using a resistor then see here,
http://httpd.chello.nl/%7em.heijlige...alogue/IV.html

Yes, I was referring to that procedure, will read, thx

Cheers

[Scorpio(DDMF)!]

Originally posted by carlosfm


Are you sure?

Guytou statement isn't true?

I was wondering if I could get the same effect with removing the op-amps, and soldering mentioned capacitor (8 µF) directly to the interconnect cable (for test purposes), and later if I should like the sound, solder the cap directly to RCA plug?

Cheers

[carlosfm]

Originally posted by Scorpio(DDMF)!
Guytou statement isn't true?

No, this isn't true:

Originally posted by guytou
(generally there is a serie resistor between the DAC and the first opamp)

Originally posted by Scorpio(DDMF)!
I was wondering if I could get the same effect with removing the op-amps, and soldering mentioned capacitor (8 µF) directly to the interconnect cable (for test purposes), and later if I should like the sound, solder the cap directly to RCA plug?

For passive I/V with the TDA1541A what works best for me is 33R.
In any case, with passive I/V, you need an output stage with gain.

[rfbrw]

Originally posted by Scorpio(DDMF)!


Guytou statement isn't true?

I was wondering if I could get the same effect with removing the op-amps, and soldering mentioned capacitor (8 µF) directly to the interconnect cable (for test purposes), and later if I should like the sound, solder the cap directly to RCA plug?

Cheers

One would not expect to see a series resistor at the output of a current-out dac like the TDA1541. The current output is normally connected directly to the inverting input of the i/v op-amp and the feedback r & c. In order to try Guytou's mod you would have to isolate the two outputs of the TDA1541, AOL and AOR, and then connect each output to ground through an appropriately sized resistor. You could then connect the junction of each resistor and its respective output, via a capacitor of your choice, to the relevant RCA.

[guytou]

hi scorpio , rbfwb said very well , this kind of DAC has a current output , and the goal of the mod is transform the current in tension by the mean of a resistor instead of an op-amp , and therefore cut the path between AOL/AOR(pin 6 and 25 of 1541) and I/V first op-amp , and tap your resistor the way rbfwb said . 100 ohms works well , with 33 ohms the output level would be too weak .Try a good polypro to begin .Anyway this mod is effective ,no-cost and reversible , worth to try .Regards .

[Scorpio(DDMF)!]

Well I did the first tweak...


I listened to proposition and bought some (aldough lower quality) capacitors, and exchanged stock ones. Sound became (to my ears) more detailed in midange ... music was very "present" and "live" (very nice change ), folowed by a little more bass...

But, I think I messed something up in the process ...

I noticed that some voltage regulators are very hot to the touch...

Let me explain: I exchanged c506, c406 with 47 µF 50V and c416, c417 with 470 µF 50V generic el cons. Was very satisfied with the sound so I let the player play for about 1-2 h.
Also, I've tried combination of 220 µF 50V caps on possitions c406 and c506...

After that I noticed that player is hoter then normal (it gets hot, but I think this time seemed a little hotter than usual), I opened it, and noticed that I can barely put a finger on IC904, 905 and 906, while IC901, 902 and 903 were only warm... (think that all ICs from this list are MC 7815CT. Also, IC401 (AD826) was little cooler to the touch, but still hot...

Strange thing is that IC904 has an heatsink (wich helps a little), while others (905,906) don't have them...

IC901, 902 and 903 have heatsinks also, but are only "plesently warm"...
TDA 1541 chip gets warm, but nothing more...

OK, this has been an long description, but the question is simple: Are regulators wich provide voltage to TDA chip and op-amps (I presume this is their task) supposed to get hot like this? Have I blown the DAC?

Opservation: Regulators get hot very quick when I turn the player ON (like in 1 min. time), but player works OK, with no aparent flaws in the sound. Also, player worked for 30 min. with no problems (didn't want to test it longer until I hear from you guys )
Regulators act the same with and without the op-amps...

Help please?

[guytou]

Hi,didn't you make accidentally a short -circuit on a supply line(with a drop of solder)?Or did'nt you mount a chimic cap upside down ?

[Kitjunky]

Some of the regs in my XB770 get extremely hot, far hotter than i would like if i was designing the unit. I think ifyou made any serious errors that the unit would not play correctly and would certainly not be sounding better. i would also recommend you double check the polarity of ur new cap's. if possible fit larger heatsinks to the reg's aswell.

Chris

[Scorpio(DDMF)!]

Originally posted by guytou
Hi,didn't you make accidentally a short -circuit on a supply line(with a drop of solder)?Or did'nt you mount a chimic cap upside down ?

Well, I do remember that I've accidently separated (in al lack of better expression) one of the legs of IC907 from the PCB (more like it was loose, not completly separated), and that player worked for an hour like that. After restoring the stock caps, I re-soldered it to the PCB... Maybe it "gave" TDA1541 too much juce?
As for the caps, all are mounted correctly (I triple check it)

Originally posted by Kitjunky
Some of the regs in my XB770 get extremely hot, far hotter than i would like if i was designing the unit. I think ifyou made any serious errors that the unit would not play correctly and would certainly not be sounding better. i would also recommend you double check the polarity of ur new cap's. if possible fit larger heatsinks to the reg's aswell.

Chris

It would be possible to fit heatsinks on the regulators that don't have tham, but I don't think it's the right way to go, simply because the regs were working without them for 20 years, so it must be OK?

In the TDA1541 datasheet it states that DAC itself draws about 45mA of current. This can't make it hot, or can it?
I'll check the regulators data sheets also to see how much current are they capable to deliver...

Thx for quick answers guys, please bear with me until I get to the bottom of this problem (or it isn't a problem, and I'm imagining it? )

Any more suggestions?
Does TDA1541 get warm in operation and do voltage regulators of this type (wich power it) get extremly hot?

Cheers...


P.S. I will also have the sm for the player soon, so I'll check all the voltages around the DAC?