"Upgrading" a Nakamichi OMS-5EII with digital out - diyAudio
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Old 8th February 2006, 11:07 PM   #1
Salar is offline Salar  Germany
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Default "Upgrading" a Nakamichi OMS-5EII with digital out

Hello,
at first sorry for my bad english...
I would like to "upgrade" my Nakamichi OMS-5EII/OMS-5AII with digital output.
This is, what I found in the service manual of the "Nak" and on the net:
The servo signal processing system oft the Nak (released in 1986) is identical to the Sony CDP-553ESD, which already had a digital out. (In fact it was the first CD-player with digital out)
Nak and Sony have the IC CX23035, which prepares the signal bevore being sent to the digital filters:
2 times oversampling on the Sony (CX23034) 4 times oversampling on the Nak (SM58048)
In addition, the Sony had an IC called CX23033, which might have been implemented in the signal path between CX23035 and the digital filters. (The signal from CX23035 seems to be serial, but the signal from the digital filters to the DACs - Phillips in the Sony, Brown-Burr in the Nak - is parallel; too late in the signal path to extract serial data for SPDIF) But I can only assume, because the information on the Sony CDP553ESD was in japanese: (sounds like a joke from Woody Allen)

http://cdp101.hp.infoseek.co.jp/cdp5...cdp553esd.html

I had it translated via google, but I can not place the link for the "translation"...

Also, somewhere on this site it was mentioned, that the IC CXD1125 replaced the CX23035 and the CX23033, so SPDIF data right from the start. But again, it was translated from japanese, but maybe the ICs are identical plus the Pins for S-PDIF data?

Does anyone have a service manual of the Sony CDP-553ESD or datasheets of the CX23035/23033/CXD1125?
Are there any other players which used the CX23035 (maybe Denon) which had a digital out? I could then try to purchase one on ebay, hopefully broken an cheap.
Or do I "only" need to replace CX23035 with CXD1125 to get a SPDIF signal?

I am no expert at all, so any help from experienced users is appreciated...
All the best;
Salar

P.S I can send schematic Diagram of CX23035 and the OMS-5EII to anyone interested
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Old 9th February 2006, 10:26 AM   #2
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You can tap and buffer the signals going to the CX23034 and feed them to a SPDIF transmitter. The AK4103, CS8406 and DIT4096 are all possible choices with the '4103 and '4096 being easier to use.

AK4103
http://www.asahi-kasei.co.jp/akm/en/...a/ak4103a.html
CS8406
http://www.cirrus.com/en/products/pro/detail/P1009.html
DIT4096
http://focus.ti.com/docs/prod/folder...t/dit4096.html
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Old 9th February 2006, 07:44 PM   #3
Salar is offline Salar  Germany
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Hi RFBRW,
Thank you for your help!
You mean, tap and buffer the signal going from the CX23035 (LSI) to the SM58048?
The next problem is the clock frequency:
The Nakamichi runs with 8.4672Mhz, which means 192fs. None of the cips you described accepts this.
I can email some pdf to you (about 3MB) with the schematic diagram of the Nakamichi, if you like to!

All the best,
Salar
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Old 9th February 2006, 09:51 PM   #4
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Yes the CX23035 to the SM5804B.
The clock issue can be addressed but I'd have to see the schematic first to determine how. The address is rfbrw at clara dot co dot uk.
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Old 11th February 2006, 07:34 AM   #5
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Put together a schematic based around a few 74 series TTL chips and the DIT4192 to give you some idea of what needs to be done. Its too big to post here at the moment and needs some refining. Hopefully over the weekend , I 'll have something I can post or email to you.
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Old 11th February 2006, 08:50 AM   #6
Salar is offline Salar  Germany
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W O W !!!

I will owe you a lot!
Just read the service manual. The Xtal runs on 8.4672Mhz, but in the circuit description it is stated, that a phased locked loop inside CX23035 produces a bit clock of 4.3218Mhz. Does this matter?
I do not have a scanner, so if you need further information/scans, it will take some days...
All the best,
Salar
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Old 11th February 2006, 10:30 AM   #7
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Hi Salar

Use a transmitter supporting fs/384 in hardware mode and a 16,9344Mhz osc to drive it. Also divide the 16,9344Mhz by 2 and use this signal to feed the Sony chip instead of the 8.4672Mhz Xtal.
The 4.3218Mhz is a product of the bitrate on the CD so it does not matter.. Older player, like mine, runs 8.6436Mhz Xtal which is twice the speed of the PLL.

Best regards

Kim Olesen
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