Old Philips DAC module - info. required. - diyAudio
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Old 14th April 2008, 08:48 PM   #1
ramchip is offline ramchip  United Kingdom
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Default Old Philips DAC module - info. required.

The PCB involved is an early Philips PCB marked "CMKS-81X" on the solder side. I think it dates from around 1989. I'm attempting to communicate with this module
using the I2C bus connected to a PIC device.
The problem is lack of knowledge about the message format required by the Philips DAC module. For example, I would like to know how to select a particular track, using the I2C bus, so I can progam the microcontroller to do this on demand.

The golden PCB contains the following chips: TDA1541A, SAA7220P, SAA7210, MAB8441, MN4264P and two LM833Ns.

If anyone has any information on this PCB, or knows where I can find it, please let me know!

Regards,
ramchip
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Old 14th April 2008, 08:58 PM   #2
guido is offline guido  Netherlands
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Default Re: Old Philips DAC module - info. required.

Quote:
Originally posted by ramchip
The PCB involved is an early Philips PCB marked "CMKS-81X" on the solder side. I think it dates from around 1989. I'm attempting to communicate with this module
using the I2C bus connected to a PIC device.
The problem is lack of knowledge about the message format required by the Philips DAC module. For example, I would like to know how to select a particular track, using the I2C bus, so I can progam the microcontroller to do this on demand.

The golden PCB contains the following chips: TDA1541A, SAA7220P, SAA7210, MAB8441, MN4264P and two LM833Ns.

Regards,
ramchip
Sounds like a pcb from a cd player, not a dac module. 7210 is a decoder. Take a service manual from any philips/marantz player from that era for more details. As for the particular pcb, guess it is trail and error looking into manuals. CD106/650 come close, but have TDA1541 without A.

However, i never saw any info on the communication between the controllers in such a manual.

The MAB on your pcb would instruct the TDA89xx chips on a separate PCB, connected to a cdm drive (cdm2 or 4/31). How did you intend to inject the music datastream???

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Old 15th April 2008, 12:46 AM   #3
ramchip is offline ramchip  United Kingdom
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Default Old Philips DAC module - info. required.

Thanks for your reply guido. I called it a DAC module for want of a better name. Maybe DAC system PCB is more accurate. All I have found so far is an overview
of the circuit in the SAA7220 datasheet, page 19. The SAA7210 is called A-chip, the SAA7220 is called B-chip and the TDA1541 is the DAC. I believe the PCB is similar to the one found in the Grundig 9000 player, as I saw
a photo on the Lampizator's website.
Anyway, I know the information I seek is more than I will find in any service manual.
I'm looking for the design manual that goes with this "DAC system PCB", if such a document exists.
Actually, the PCB is part of an old jukebox so the original designers must have had access to the I2C bus message formats that were necessary to make it work.
If I could find that information the problem would be solved!
The DAC system PCB connects to a cdm drive via ribbon cables. The audio signal comes from connectors on the DAC system PCB. I suppose if it turns out that the message format is proprietary to Philips then I will have reached a dead end. In the meantime I shall remain optimistic!

Regards,
ramchip
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Old 15th April 2008, 07:02 AM   #4
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You can no more select a track by talking to the module than you can move the tonearm by moving the phonostage. The module or a control unit talks to the disc mechanism and it moves the laser accordingly.
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Old 15th April 2008, 01:01 PM   #5
ramchip is offline ramchip  United Kingdom
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Default Old Philips DAC module - info. required.

I am trying to communicate with the control unit via the I2C bus. There is a connector on the PCB specifically for this bus and that's how the control unit is addressed in the machine. So far I can see messages on the bus which show the idle state and the play state, using a bus trace program I adapted for the PIC.
I know for a fact that the track selection for this machine is done using the I2C bus. What's not clear, at the moment, is the message format for track selection. Any help with how this is done would be much appreciated. Hopefully, someone might know about the CMKS-81X circuit board and it's mode of operation.

Regards,
ramchip
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Old 15th April 2008, 03:06 PM   #6
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If you have the cd mechanism, then you have the model mumber and from there you can get more information.
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Old 15th April 2008, 11:29 PM   #7
guido is offline guido  Netherlands
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Get a philips/marantz player from that time with multiple controllers. e.g. philips cd650. Good chance they all use the same communication protocol between display/keys and main controller.

Reversed engineering
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Old 16th April 2008, 12:54 PM   #8
ramchip is offline ramchip  United Kingdom
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Default Old Philips DAC module - info. required.

Thanks for replies. Maybe a service manual for the Grundig CD-9000 player would help, as it contains a PCB very similar to the one I have.
I've just finished a Google sesssion looking for this manual without success.
Does anyone know of a source for this service manual?

Regards,
ramchip
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Old 16th April 2008, 01:57 PM   #9
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can you take a photo of the board?

sp
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Old 16th April 2008, 05:20 PM   #10
ramchip is offline ramchip  United Kingdom
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Default Old Philips DAC module - info. required.

Okay, I've resized the picture for uploading.
DACsysPCB.jpg shows the layout of the chips.
Upper row left to right: SAA7220P/B, MAB8441+heatsink, SAA7210, MN4264P-15
Lower row left to right: TDA1541A, LM833N, LM833N.

Hope this helps!

Regards,
ramchip
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