RGB cable for japanese MSX computers and J-SCART

WARNING: Procede at your own risk. You’ve been warned. I can’t be held responsible for any damage.

All japanese MSX2, MSX2+ and TurboR computers have RGB out on a DIN-8 connector. The pinout for this connector is available at Ultimate MSX FAQ: http://www.faq.msxnet.org/connector.html#rgbjap

     7     6
    3   8   1
     5     4
        2
    
    1 GND
    2 AUDIO
    3 NC
    4 C SYNC
    5 +5V
    6 R
    7 G
    8 B

Note: if you mod your MSX for PSG stereo output (ABC or ACB), you can use pin 1 for “AUDIO LEFT” and pin 2, which is not used by default, as “AUDIO RIGHT”.

Our goal is to connect MSX RGB signal to a device with J-SCART input (for example Micomsoft XRGB* family of upscanners or XAV* RGB to S-Video converter series). The pinout for J-SCART is available from GameSX: http://www.gamesx.com/avpinouts/rgb21pinj.htm

      1                 19
    +---------------------+
    | | | | | | | | | | |  \21
    |  | | | | | | | | | |  \ 
    +-----------------------+
       2                 20
    
    1  R AUDIO
    3  L/R AUDIO GND
    5  L AUDIO
    7  C SYNC GND
    9  C SYNC  
    13 R GND
    15 R
    16 +5V
    17 G GND
    18 B GND
    19 G
    20 B
    21 GND

Note: there are only 20 pins. Pin 21 is actually shielding that protects connector.

I didn’t know if GameSX pinout is 100% acurate. What I did is order a known working XRGB cable for SEGA Genesis model 1, and then just replaced connector on SEGA part with japanese MSX RGB connector. Here is what I ended up with:

    DIN-8     J-SCART  
    
    1         3,7,17
    2         5
    3         1 (*)
    4         9
    5         16 (**)
    6         15
    7         19
    8         20
    Shielding 21

* Optional. You only need this signal if you plan to add PSG stereo mod.

** Optional for XRGB and XAV. I think you only need this signal if you plan to use japanese TV or VCR with J-SCART. I think that 5 volts on pin 16 switches japanese A/V gear from composite to RGB mode.

As you can see, I don’t have J-SCART pins 13 and 18 connected with the rest of the GND pins. The cable works without them, but it might be a good idea to connect them to DIN-8 pin 1, just like we did for 3, 7 and 17.

A good source for quality cable is any used VGA cable. I just cut off a cable from a dead old 14” VGA monitor. It has thick copper wires for R, G and B signals, each with it’s own shielding as well as one common shielding. Also there are four extra wires without separate shielding (in my cable they are white, black, orange and yellow) that you can use for mono or stereo audio, sync signal and +5v. I would stick to following convention: use yellow wire for +5v, white wire for mono/left audio, orange wire for right audio and black for composite sync signal.