av:japanese_rgb-15 [NFG Games + GameSX]

Japanese RGB-15 Connector
- X68000
- PC 9801
- FM Towns
- CAVEATS

Japanese RGB-15 Connector

This connector is the standard for many pre-DOS/V (IBM compatible) computers in Japan. The PC-9801, X68000 and FM Towns all used this pinout, or similar variants of it. Pay attention to the differences, they are important!

NOTE the numbers are usually visible on the connector itself. If you're looking at the business end of the female connector, pin 1 is on the right. On a male connector it's on the left.

X68000

Pin	Function	Pin	Function
1	Red	9	NC
2	Ground	10	Audio L
3	Green	11	Audio R
4	Ground	12	Ground
5	Blue	13	NC
6	Ground	14	H-Sync
7	Ys	15	V-Sync
8	Ground

Ys = computer data present. Usually +5V

PC 9801

The PC-9801 connector is nearly the same as the X68000. The differences are very minor: pins 9 and 13 are used for the 9801, but are not connected on the X68000.

Pin	Function	Pin	Function
1	Red	9	Ys
2	Ground	10	AV Control
3	Green	11	Mode
4	Ground	12	Ground
5	Blue	13	Dot Clock
6	Ground	14	H-Sync
7	Ys	15	V-Sync
8	Ground

Ys = computer data present. Usually +5V

FM Towns

Pin	Function	Pin	Function
1	Red	9	Ys
2	Ground	10	AV Control
3	Green	11	Mode
4	Ground	12	Ground
5	Blue	13	Dot Clock
6	Ground	14	H-Sync
7	C-Sync	15	V-Sync
8	Ground

Note that some FMTowns systems used a VGA connector.
Ys = computer data present. Usually +5V

CAVEATS

Not all systems put out power on pin 7. Normally +5v, some devices (like the X-RGB2) leave this pin disconnected. You can add power to your cables, for monitors that require it, following these directions.
Remember that the pin numbers are almost always found on the connector itself.

Credit:

Some of this info came from this Japanese page.