Sony CDP-M69 mods

[ZuMbAiU]

I have from today one Sony CDP-M69 like new.I want to mod this player.May be I can use Nichicon capacitors,because in this player I have ELNA capcitors.May be a new pre-amp and may be I can make it non-os.I have two PCM56 DAC`a in this player (8 times oversampling ,18 bit)and new KSS laser.
I wait for any suggestions
Thanks

[triode_al]

Today I modded a Sony CPD M69. The output of the two PCM56's is made passive. The output filter is made 6db/octave.
This is how I went ahead:
Creating a passive I/V conversion:
1 disconnect the pins 9, 10 and the pins 11, 13.
2 cut the connection to resistor R 501/601 (820 ohm).
3 Then take a resistor from pin 13 to the common ground that is also under the output opamp. (Scratch the paint/isolation and drill a hole there). I used a 470 ohm resistor, plain. This is the analogue ground.

Creating a simple output buffer based on the existing MC4558:
3 take out the capacitors C 501/601 and C 502/602 (2n2 and 6n8).
4 add a new capacitor of 1n8 (styropor is what I used) from pin 3 and 5 to the ground (thye same analogue ground that the I/V resitor is tied to.
5 Now you have a 1x output buffer that has a 6dB passive slope of 66 kHz (the two 820 resistors are still in place and the 1n8 cap gives this point)

Connect the ouput cinch:
6 take out the output electrolytic (10 muF)
7 drill out the holes a little bit so a larger capacitor lead fits in. Do the same near the output pins.
8 place a 1,5 muF oil-in-paper capacotor, 100V value, striaght from the opamp output to just in front of the 220 ohm output resistor. Or you can take that out and place the capacotor lead directly onm the output pins of the chassis.

Improve decoupling
9 add a 220 nF capacitor from pin 16 (analoge V+5V) to pin 12 (in fact on the common analogue ground that the resistors are also placed on.) Note that the schema has a strange ground plane.There is no separation of the analogue from the digital V+. The analogue electrolytic is not the the analoque ground even, but with the new decoupling capacitor there is some help at least). I used a Taitsu cap.

And: presto. Improved sound, nice stage and depth. Details. Easy to listen to.

Compared with my passive NonOS-TDA1541 (based on a Philips-made CD1006 deck) the sound is less direct but seducing. The 1541 has the real slamming bass needed in a lot of music.

Yes, the Sony after conversion is still 18 bits, and 8 times oversampling.

The traces
On the scope I see that the -60dB signal from Pedja is still very into the background noise. [Compared to the TDA1541 traces stand out much better and has betterS/N.]
Before the modification I saw that there were a lot of glitches, digital noise, on the -60dB signal. This has disappered.

Still to do, later:
a) add a new power section for the PCM56's that is independent from the digital line.
b) add a new power section for the MC4558 buffers with at least +/- 15 Volt (it can have up to 20 V power) to improve the speed.
c) Take a resistor from the MC4558 output to V- to force the opamp to an class-A status.
d) add a triode output section that amplifies 3 times

albert

[triode_al]

I have gotten the Sony CDP-M69 for a next upgrade: add a low jitter clock (Tent) of 16,9344 MHz.
This is on the CDX-2551P chip (evidently an inverter chip).
However, I can't find the data sheet for this chip.
Does anyone have this info for me?
thanks
albert

[coolhead]

Go and download a service manual for it Sony - CDP-M48, CDP-M49, CDP-M69 Service Manual on Windows Drivers Downloads

[triode_al]

Originally Posted by coolhead

Go and download a service manual for it Sony - CDP-M48, CDP-M49, CDP-M69 Service Manual on Windows Drivers Downloads

Thanks, but that is a paid site! The manual will cost me $8. I am not a business.
albert

[triode_al]

I found the CDX2551P (without the dash), and that is the correct one of course. [I had google expected to be smarter ..]

In this digital filter chip, pin 3 is clock out and pin 4 is clock in.
From this it is distributed to the main chip CDX1125 to pin 53. Of that, pin 54 (normally out to clock) is not connected; the CDX2551 manages the clock signal distribution. There is a 330 ohm resistor and a 1 k resistor in series from CDX2551P to CDX1125 - It might be better to distribute directly from the clock using a 100 ohm ni resistor.

I removed the crystal and capacitors C321/322.
I connected to the crystal leg connected to pin 4.
[Note: it works also with connection to the other leg]

So now to the listening area.
albert

[triode_al]

A quick listening:
the M69 versus a sony CDPXB920: the M69 no has a more natural sound.
Alfred Deller songs.
The silence in this voice is deeper; string instruments have a more natural tinge to them.
But alas it is not mine . . .