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How to get your beloved CD-player from the eighties into the Digital Domain
How to get your beloved CD-player from the eighties into the Digital Domain
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Old 19th October 2006, 11:03 PM   #1
Salar is offline Salar  Germany
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Default How to get your beloved CD-player from the eighties into the Digital Domain

Hello,

Some days ago, I finished my work in upgrading my Nakamichi OMS-5EII with a S/PDIF output.
This CD player was developed in 1986, (bought mine in 1990) so this post might be interesting for those, who own a player from this time, when a digital output was not common.
The OMS-5EII, as well as the OMS-7EII have a PCM decoder from Sony, CX23035.
Sony used it also for the first consumer model with S/PDIF out named CDP-552ESDII. It came to the market the same year as the Nakamichi.
So, If this PCM decoder is used (I.e. the Denon DCD-1500 has it, and probably many other japanese high end CD players ), chances are very good for upgrading.

I am not a technician at all, so I want to give big thanks to some people, I think three of them are users in this forum, for helping me:

- At first to Ray, who developed the schematics for the digital output
- Jobstens (www.jobstens.de), who checked them and gave me many tips
how to handle ESD and heat-sensitive devices
-Frank who proposed a I2s output
-Uwe (http://beis.de/Elektronik/Electronics.html) for practical tipps in wiring the board and providing the output transformers needed.
-Stefan for proposing a company which solders SMD devices

I do not have a scope or anything like that, so building the digital output was a matter of "plug and play".
If it did not work, it would have been impossible to find errors.

For upgrading, Ray and Jobstens proposed the DIT4192 from TI, a digital transmitter which does not need a controller. An octal buffer, 74HC240N was used for transferring the signals from the CX23035 to the DIT4192.
One problem was, that the Nakamichi worked internally with a
master clock rate of 156fs, but the DIT4192 needs 384fs.
I bought a clock from Tentlabs, which provides both frequencies: 8.4672 for the Nakamichi s CX23035 and 16.9344 for the DIT4192.
One nice side effect of the upgrade is, that the Nak now sounds "fresher" because of this almost jitter-free clock.
I also replaced all electrolytic capacitors of the "Nak", (also on the D/A Board) but this did not have any audible effect to my ears.

I did not want to stress the power supply of the Nakamichi, so the tentlabs XO and digital output circuitry got their own power supplies.
But shortening the pins of the S/PDIF (even though a decoupling transformer was implemented) made the laser loose track.
But with the buffer being connected to the Naks 5V power circuitry, everything works fine.

The only problem was (and still is), that my DAT-recorder (Sony ZA-5ES) does not recognise the S/PDIF signal.
Experimenting with several modes of the DIT4192 did not help.
But my sample rate converter (Z1-SRC), my portable DAT (AIWA HD-S1) and soundcard (ESI Juli@) receive the S/PDIF with no problems, so I blame it on the Sony.

The next and final step would be implementing an up to date D/A board which can be hooked on the S/PDIF out. But the Nak sounds fine, I will see...

One request: If anybody reading this post lives in the Berlin area and has a scope, it would be fine to meet.
Before and also after the upgrade, the Nak has sometimes problems to find a track when skipping over a longer distance. I replaced the laser three years ago and did also replace the motors when doing the upgrade but it had no effect, so I think it is a matter of realignment...

All the best,
Sal
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Old 19th October 2006, 11:10 PM   #2
Salar is offline Salar  Germany
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One photo of the Naks digital board...
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Old 19th October 2006, 11:11 PM   #3
Salar is offline Salar  Germany
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And a top view...
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Old 23rd October 2006, 01:44 PM   #4
Salar is offline Salar  Germany
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The Nak reassembled...
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Old 3rd April 2016, 01:50 PM   #5
chapai123 is offline chapai123  United States
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I get OMS-5AII too, so very interesting to implement the same, as original DAC sound too simple. Thanks for the idea of implementation
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Old 30th November 2017, 04:01 PM   #6
NATDBERG is offline NATDBERG  United Kingdom
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This is long ago but I have an OMS -7A MK I. I guess might not be so simple?
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Old 24th December 2017, 08:33 AM   #7
Salar is offline Salar  Germany
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No, not at all. But there is a guy in Germany who did this for a Philips CD 104
wich has the same Philips chipset asthe Nakamichi

DJ9KW

Page is in english, look under "Projects"
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Old 24th December 2017, 02:25 PM   #8
Malefoda is offline Malefoda  France
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Nice work in a world of dying CD players
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Old 24th December 2017, 02:38 PM   #9
anatech is offline anatech  Canada
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How to get your beloved CD-player from the eighties into the Digital Domain
Hi Salar,
Nice going! I'd very much like to have a digital output on my OMS-7 too! My biggest problem is time.

Your tracking problems are partially alignment and partly because that model really never did track that well on defects or bumps. Your problem sounds like straight alignment.

That head (Sony KSS-123A I think?) can have a problem where the centre post used to keep the lens in alignment can become sticky. This mostly affects focus as the lens assembly has to move up and down the post. With power off, the lens should move completely freely up and down on that post.

-Chris
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Old 24th December 2017, 04:35 PM   #10
audioengr is offline audioengr  United States
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Much simpler to just add a good reclocker, like a Synchro-Mesh.

I modded my old Phillips CD player, which I loved, but with new master clock and output stag, but never achieved this kind of low jitter (20psec). I ultimately added the reclocker and all is good.
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