Dolby Cat. 680 bit rate converter board

Hi folks


Does anyone have any info, especially a schematic for the Dolby Cat. 680 bit rate converter board? All I know is that it was for the CP500 Cinema sound processor.
 

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Thankyou, hopefully we can have an on-topic discussion now.

There are two main reasons I ask about the AD1893. Firstly, there is very little about in online, the datasheet is available of course, but there are very few mentions of it apart from that, not a single circuit schematic to be found, it just seems to be a very uncommon chip to see utilised, so information is very lacking.

Secondly, the primary application I could find was in TEAC's high end VRDS CD player, but most of the discussion around that application centres on removing the AD1893, such as this mention here:

TDAC1543 - Non oversampling DIY DAC

AD1893:
Very noisy signal processing, limits the SNR of this player to 95dB . Performs some additional digital filtering (not needed, and degrading impulse response) and offers jitter rejection when connecting an external transport. Upsampling 44.1kHz to 48kHz does not offer a real benefit, since the 44.1kHz are later oversampled by a factor of eight (and not only by a factor of 1.1)
Let’s remove this IC.
 
Here's some better quality pics of the board:


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As there is such a paucity of info on the AD1893, I looked at what was available on the other Analog Devices SRC ICs such as the AD1890/1 and AD1896, they are similar but different.

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I did find some information that is quite helpful in an Analog Devices application note:

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Another app note about designing a DAC gives some details of how to implement the AD1890/1 and should also be applicable to the AD1893:

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Hi! You will not find a service manual for the CP 500. Probably they are not on the Internet, I myself have been looking for it for a long time, Dolby apparently does not distribute it, and very few engineers have such instructions.
As a result, I quit looking and try to figure out this board myself