CDM1 transport

[Happy Ears]

Dear forum members ,
I'm looking for some background info about this CDM1 transport .
I own two Philips CD104 players in perfect condition .... not the last word in overall performance but would like brew a nice toploader CD drive in the future ( CDM1 seems a serious transport ) ..
Any advice is highly apreciated !!!

Happy Ears

[Netlist]

Originally posted by Happy Ears

Any advice is highly apreciated !!!
Happy Ears

I guess the best advice is already here:
http://www.diyaudio.com/forums/searc...der=descending
and here:
http://www.diyaudio.com/forums/searc...der=descending

Happy hunting

/Hugo

[jean-paul]

Yes, that good old Search function that nobody uses...

[EDUM]

Congratulations Happy Ears!

What do you want to know?

Regarding the CD104 I have two tips:
-replace the output capacitor. A tantalium one I believe. This improves the sound quality a lot.
-In case of servo trouble check the connections between top- and bottomlayer of the PCB (resolder them).

The CD104 makes a nice start for a DIY project.

Have Fun!

Ward

[Happy Ears]

Thanks Guys !

Edum , I wanna use it as a stand alone drive with I2S outputs .
I could use the existing electronics for controle functions ... but I'm not sure where's best point to pick up I2S format ( didn't study the chip files yet ) and one could offer a perfect strategy here . I hope !

I guess power supply and system clock could be better too ...

I will read all earlier messages on the forum first . but any input of course could be valuable .

Yours,
Happy Ears

[guido]

Using the existing controlfunctions will be the easiest way to get it working. Making you own controls is v. difficult (there is a post on that from a few weeks back). Your controls need to be adapted to the cdm type.

About i2s, the chipset is the probably the first one. So with the 14 bit DAC's. The decoder and error correction are separate chips, there is a dig filter and then 2 dacs. The decoder will decode 16 bits from the cd. So somewhere it goes from 16 bit into 2 times 14 bit (non i2s, mono dacs). I think before the dig filter, but i don't know if it is i2s there or something predating that spec.

Finding datasheets on the chips is difficult, i have only some ifo on the dac's. I do have a manual for the B&O cdx, i'll have a look in there, it has the timingdiagrams between all chips. Before anyone asks, it's too big to send around. My internet is still limited bandwith and i am not going to mail it around (yet).

GuidoB

[EDUM]

Hello Happy Ears,

Cdm0 (your photo) and cdm1 have complete analog electronics. So using the servo and control of the CD104 is a good idea.

First of all how much do you want to change? My tip of replacing the output capacitor makes a difference. But I guess you realy want some more
You can have an external DAC or maybe just replace the internal DACs.
I dived in some databooks and found a SAA7274 which translates Philips/Sony format to I2S. Looked at some DACs, checked a CD960(cdm1 and digital output) manual. Several options worthwhile to study

As I am not a digital expert I can not say how easy this options will turn out. I sugest you first try to get a service doc. I have the feeling that studying that service doc, chip files and work done by others on this forum you will find something feasable.

Have Fun!

Ward

[guido]

Hi,

Had a quick look at my cdx manual (~philips cd104 inside ?). If you find SAA70xx inside, together with two TDA1540, you have the old 14bit chipset. The 7030 is the dig filter. Indeed 16 bit in and 14 bit out.

However, the 16 bit input is NOT I2S. There are four lines:

STR1 with a small pulse every 22.5 microsec (=1/f with samplefreq 44.1kHz) CLCF with 16 pulses after the STR1 pulse during 7.5 microsec. then 15 usec nothing. DLCF with 16 databits, clocked on CLCF pulses. Left channel only DRCF like DLCF, but now right channel.

Maybe some old BB DACS can handle this format (with STR1 inverted?). I only have some small diagrams used for checking the signals on a logic analyser. Not enough detail there to make
logic for conversion.

My advice would be to only fiddle around in the analog and PS department. The dig part is complicated and not compatibel it seems.

If you really want a CDM1 toploader i would suggest to buy a cd-x :-> And if you want one which has I2S, buy a cd-x 2 (cdm2,7210,7220,1541).


GuidoB

[Happy Ears]

Originally posted by guido
Hi,

Had a quick look at my cdx manual (~philips cd104 inside ?). If you find SAA70xx inside, together with two TDA1540, you have the old 14bit chipset. The 7030 is the dig filter. Indeed 16 bit in and 14 bit out.

However, the 16 bit input is NOT I2S. There are four lines:

STR1 with a small pulse every 22.5 microsec (=1/f with samplefreq 44.1kHz) CLCF with 16 pulses after the STR1 pulse during 7.5 microsec. then 15 usec nothing. DLCF with 16 databits, clocked on CLCF pulses. Left channel only DRCF like DLCF, but now right channel.

Maybe some old BB DACS can handle this format (with STR1 inverted?). I only have some small diagrams used for checking the signals on a logic analyser. Not enough detail there to make
logic for conversion.

My advice would be to only fiddle around in the analog and PS department. The dig part is complicated and not compatibel it seems.

If you really want a CDM1 toploader i would suggest to buy a cd-x :-> And if you want one which has I2S, buy a cd-x 2 (cdm2,7210,7220,1541).


GuidoB

Hi Guys !
I checked the chips inside .. indeed SAA7020 / SAA7030 and double TDA1540 configuration .. must be one of the very first examples I guess .

Guido , does the CDX manual says how this data format is called ?? It would be very interesting to get some more info about this , there might be a possibillity to convert it into another ( more handy format , like I2S ) ?? purpose ... TDA 1543 / TDA 1541-R1 dac brews .

Ward , thanks too ! I believe If I cannot get the player run with the desired I2S streaming , I better choose another path .. like Guido mentioned .. or perhaps the CD2-pro package ... many ways that leads to Rome .

Let's wait ... who knows some digifreak is willing to share his expirience with the early data formats ... thought about asian wizzkids or Philips insiders key:

Happy Ears

[Happy Ears]