Providing Digital Out to a Nakamichi OMS-5EII

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Hello,
a year ago, I asked for help in upgrading my 20 year old OMS-5EII with a digital output. Jobst and Ray were very kind to help me with tips and Ray even did sent me a schematic. But I am an absolute amateur! I am working as a film editor, sounddesigner, sometimes cameraman, sometimes field recordist, so I have some technical skills in keeping the gear running and how to solder tiny pieces together, but that´s it. Only a voltmeter at hand and a soldering iron.
In the meantime, i got a service manual from the Sony CDP-552ESDII, which used the same digital LSI as the Nak (CX23035) but provided digital out. (the Sony was the first consumer player in the market with digital out) So I had double information.
But some namings of the pins of CX23035 differ, I hope, it is only a matter of non-common terms 20 years ago and not a programmable LSI.
I drew a schematic based on Ray´s using scans from the service manuals and additional parts (i.e. DIT4192) in order to learn the real world layout of the pins.
Could anybody check this schematic? Again, i am an amateur...
My schematic is a .pdf but it is too big (1MB) for attaching it to this post.
So please feel free to email me:
salar at snafu dot de

About the schematic:
I am not sure, wether the connections between the Digital LSI and the digital transmitter are correct. Also, there is one octal buffer (74HC244) implemented, which might not be needed.
The modification would also need a new oscillator of 16.9344 mHz for driving the DIT4192 and being divided in two for the CX23035.
(Sony did the same with the CDP-552ESD). Even though this would be an occasion for implementing a jitter-free clock (i.e from Tentlabs), I would rather prefer a design using the original oscillator and double the frequency.
Any advice on this?
Supplying power will be the next problem (at least for me)
Once, i provided the tray of the OMS with 4 LED´s. I took the power (5V)from the circuit driving the cable(!) remote control, but this extra 80mW blew a resistor in the servo circiut after some weeks (in the moment the tray opened an the LEDs went on)
Now they run independent on a small power transformer, but the transformer only provides 3V. After this experince, I am a litte hesitant to apply some extra milliwatts to the Naks powersupply. But I can send the schematics and description of the power circuit of the Nak to anyone intersted.
In case anybody wonders why upgrading such an old player:
I like its quality! And I have two laser units as well as motors still in reserve, so this baby should work for some decades to come - hopefully with a better (modern) D/A Converter, which will be attached to the digital out...

Thanks four your kind help in advance,
all the best,
Salar
 
Hi Solar,

Doesn't the Nak have Philips d/a converters (TDA1540) in it?
If this is the case it is possible to exchange the Saa7030 and Saa7000 with the SAA7220b. It is a bit tricky but i have done this in a philips cd304 to ugrade it to a 304mk2 10 years ago.
 
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Hi wsjoe,
They used the NEC #79710002 P/U head. A true precision assembly. The head is mechanically adjustable in all three axis. The disc motor is also a very well built assembly.

Once the mechanical adjustment is made and locked (all die cast and milled pieces :D ) the electrical adjustment is made. This results in the most stable and cleanest eye pattern I have ever seen in any CD player. All this transport needs is a better digital filter and D/A stage than the Philips TDA1540 chip set.

How do they compare against the Denons?
Better tracking, but poorer sound quality.
SUch as DCD-3520 and DCD-3560? Or even lower such as DCD-1560 1520 or 2560.
Those are all excellent machines. The transport is better than average, but not as good as the OMS 5/7. The digital and analog stages are better than the Nak. Understand that Nakamichi squeezed out far better sound quality than you could imagine with these Philips parts.

-Chris (well, that's my opinion anyway) ;)
 
Sorry my bad, I thought just about controler had a digital take off point, I've yet to come across one that has'nt, and done quite a few that had no coax or toslink outputs, admitly never done a Naka.
Just had a quick search and I found that the CX23034 which is suppose to be closely related to CX23035 and pin 19 on this will give the tap for the X03 to make it's digtal spidf out work. Could'nt find the data sheet for the 35, but i did'nt try too hard either.

Cheers George
 
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Hi George,
Just had a quick search and I found that the CX23034 which is suppose to be closely related to CX23035 and pin 19 on this will give the tap for the X03 to make it's digtal spidf out work. Could'nt find the data sheet for the 35, but i did'nt try too hard either.
No problem. You would have to look at the early Philips SAA7010 / 7020 / 7030 type chip sets. Nothing to work with.

Nakamichi did an amazing job of making these sound good. DACs were TDA1540P - 14 bit.

-Chris
 
georgehifi said:
Sorry my bad, I thought just about controler had a digital take off point, I've yet to come across one that has'nt, and done quite a few that had no coax or toslink outputs, admitly never done a Naka.
Just had a quick search and I found that the CX23034 which is suppose to be closely related to CX23035 and pin 19 on this will give the tap for the X03 to make it's digtal spidf out work. Could'nt find the data sheet for the 35, but i did'nt try too hard either.

Cheers George


The CX23034 is closely related to the CX23035 in the same way the SAA7210 is closely related to the SAA7220. They work together.
 
I have a NAK OMS-5A mkII and it has a very nice separate DAC board:
digital photocouplers to receive and transfer (galvanic isolate) digital data, 3 separate power supply rectifiers (one for digital section (DAC), one for analog-L, and one for analog-R), discrete transistor audio amplifier section with capacitorless output, 16 bit BurrBrown PCM54HP DAC (one for each channel) and absolutely no electrolytic capacitors (except those 3 ones in power supply rectifiers). It sounds absolutly warm and lush. This DAC board is very autonomous and only has two bridge connectors from outside: one for +/-15Vac and ground from main power supply and other to income the digital data (split R-L digital data, bitclock, wordclock, 5Vdc, GND, Mute and De-Emphasize relays controls).

I'm just wondering if I could do the opposite SPDIF project shown in this thread: to build and incorporate an SPDIF input for the DAC section (to use the NAK only as a DAC).

The only things that by now are worries for me are the following:
The splitted digital data input (R+L) in the DAC and how to obtain this from SPDIF input.
The decision to use the DAC as a NOS DAC (without the use of the digital filter, or Non Oversampling DAC) because the digital filter section (SM5804B) is on the other board (digital pick up, signal processing and control board).

So, anyone tried to do some kind of similar diy job?
Any suggestions?
 
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