Hello,
it seems a bit odd but I'm not able to find the DAC chip oft this mostly "unknown" CD Player which I did get for next to nothing as a little fun repair project .
It is a Palladium HCD-221 branded model of a not known to me manufacturer.
I was not able to hit any documents or a service manual on the www.
The chips in the mainboard section which is marked "D/A Convertor" seem to be logic ICs from what I found in the data sheets.
Any ideas?
Thanks in advance,
Rudolph
it seems a bit odd but I'm not able to find the DAC chip oft this mostly "unknown" CD Player which I did get for next to nothing as a little fun repair project .
It is a Palladium HCD-221 branded model of a not known to me manufacturer.
I was not able to hit any documents or a service manual on the www.
The chips in the mainboard section which is marked "D/A Convertor" seem to be logic ICs from what I found in the data sheets.
Any ideas?
Thanks in advance,
Rudolph
Attachments
This is the IC which is below the rectangular electric screen plate in the middle oft the board next to the two op-amps screwed to the vertical cooling profiles.
The next 2 pics show the 3 ICs in the back oft the mainboard.
Sorry for my unprofessional pics. I hope the essential can be Seen.
The next 2 pics show the 3 ICs in the back oft the mainboard.
Sorry for my unprofessional pics. I hope the essential can be Seen.
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Extreme_Boky, thank you very much for your fast reply. What makes you confident about CXD1135 doing the DAC job? Unfortunately I could not find a data sheet for it.
This list CD-Player-DAC-Transport Listshows no entry with CXD1135 as a standalone DAC. It's mostly combined with PCM54, PCM56 or LC7881.
This list CD-Player-DAC-Transport Listshows no entry with CXD1135 as a standalone DAC. It's mostly combined with PCM54, PCM56 or LC7881.
There is no dac in the CXD1135Q. The dac in this particular model is discrete and consists of the resistor arrays and the logic chips. It accepts parallel data from the CXD1135Q and is shared between channels.
What is the IC I have noted on your picture.
I think this may be it.
P
No, actually is that a CXA1081?
RF Amp IC. My mistake.
I think this may be it.
P
No, actually is that a CXA1081?
RF Amp IC. My mistake.
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At first, I did not really take the labelling too seriously, but, the DAC section is indeed done with the logic IC's and resistor arrays. It is a textbook R-2R implementation... they used a Zener, resistor and a capacitor to generate Vref... It would be interesting to find out how many resistors are in those SIL resistor arrays RA1 and RA2...
@blackground
Could you please count the RA1 (or RA2) pins??
@blackground
Could you please count the RA1 (or RA2) pins??
If that's the case, that's pretty interesting.
More information needed please, from anyone. Any schematic out there?
P
More information needed please, from anyone. Any schematic out there?
P
Yeah, I'd like to know how they are achieving 15-16bit resolution.... RA1 and RA2 are max 12-resistor arrays... I think... there's also some fast switching between L and R channels happening, so the schematics would be interesting indeed.
Thank you all for your helpful comments. Really appreciate that.
There seems to be consensus about a discrete DAC section built by logic ICs and resistors. I'm very happy that this question that haunted me the last week now is answered.
There is some probability that right and left channel use the same one DAC section since there is one analog multiplexer/demultiplexer in this board area. This is the 16pin Mitsumi HD14053BP.
I assume that the digital to analogue conversion drops some of the 16 bits since this CD player is an early absolutely entry economy model. Only a brand of an once well known German mail-order outlet Neckermann.
I added some more pictures oft the player itself. I would locate the player in the mid 1980s by its design.
Any infos, technical specs, manual or schematics are impossible to find for me with the usual www ways. I'm very corious about if it is oversampling or not, its THD, original manufacturer...
There seems to be consensus about a discrete DAC section built by logic ICs and resistors. I'm very happy that this question that haunted me the last week now is answered.
There is some probability that right and left channel use the same one DAC section since there is one analog multiplexer/demultiplexer in this board area. This is the 16pin Mitsumi HD14053BP.
I assume that the digital to analogue conversion drops some of the 16 bits since this CD player is an early absolutely entry economy model. Only a brand of an once well known German mail-order outlet Neckermann.
I added some more pictures oft the player itself. I would locate the player in the mid 1980s by its design.
Any infos, technical specs, manual or schematics are impossible to find for me with the usual www ways. I'm very corious about if it is oversampling or not, its THD, original manufacturer...
It seems that pin 59 controls the parallel signal output channel allocation. This signal then goes to MPX filter that separates left and right audio signals, with a help of, what reminds a lot of, the notch filter (pin 60 and 61). The whole thing reminds me of analog tuners and the way they used to separate left and right signals...
I have found some limited info on Yamaha filter IC, and extracted the D/A section, with a bit of sharpening added to make it easier to read.
It seems that the D/A converted does indeed provide a "full" 16-bit resolution.
It is definitely nice to see the original DAC, as implemented at the beginning of the digital audio playback era.
I have found some limited info on Yamaha filter IC, and extracted the D/A section, with a bit of sharpening added to make it easier to read.
It seems that the D/A converted does indeed provide a "full" 16-bit resolution.
It is definitely nice to see the original DAC, as implemented at the beginning of the digital audio playback era.
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