You need the plug in this picture
the standard is :
from the bottom of the picture up:
large plug
Red, Green, Blue, Ground, +vert sync, +horiz sync, blank(key),
small plug
ground, -vert sync, -horiz sync
Odds are you need to hook:
from arcadevga harness to plug in picture
red to red
green to green
blue to blue
all grounds to ground
nothing to + vert sync
both sync wires to + horiz sync
That works on most monitors
there is a picture on the right inner side of the chassis that will show what the pins on that plug are. the above first four connections are standard...re-red, green-green, blue-blue, all gnd-gnd the only odd one is the sync wires ...some monitors want both to + h sync, some to + v sync, some to - h sync, some to - v sync, and some want them hooked up individually. Hook the colors and ground up first, then first try both sync from arcadevga twisted and try each sync wire on the monitor...one should work