Get digital signal from an old CD-Rom without digital output

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I am using two old external SCSI CD-ROMs manufactured back to around 1993-1994. Both have no digital output of audio signal. I have been very happy with them as CD signal source for them give good music while playing at 1X speed and after the power supplies been modefied.

One is a NEC 3Xplus CDR-600 with decoder "SONY CXD2549Q".
Another is a Plextor 12X with decoder "SONY CXD1808AQ".

I guess there might be some way to pull the digital audio signal out. Does anyone have similar experience??

BTW, does anyone have the spec sheet of SONY CXD2549Q??

Thanks and Happy New Year!!
 
If you have a scope, probe around for the three key signals:

1. BCK - this should be around 2.1 Mhz.
2. LRCLK - this should be 44.1kHz.
3. Data - look for signal that are random, active when there is music, and dies down when there are none.

This three signals are the EIAJ or Sony format. You need glue logic to convert to Philips I2S outputs. Else you can use TDA1543A.

To help you narrow down the search, look for the DAC which should be ( I think PCM1715 ), and you will be able to know where the three pins are.

If you want SPDIF, then I cannot help you and you will need the datasheet I guess.

I used the above to find the pins for my CXD1135 and it worked great.
 
Don't know the technical terms. Download the SAA7345 datasheet from the philips semicon website. In there you wil find the detailed timing diagram of EIAJ side by side with I2S. I used the timing diagram information to design my EIAJ to I2S converter. It works. The schematic had been posted in this forum unders haring my digital work.

CM
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.