Games Family 2477-in-1: No video to Arcade Monitor - HELP!!!

[Brizzle]

I have a Makvision 2425 standard/medium resolution monitor that works when hooked up to a 60 in 1. I have a Games Family 2477(or something) in 1 that I picked up used in trade for designing cabinet graphics, sworn to be working when pulled. I hooked up a new jamma cable, correctly wiring the 12v, +5v, -5v, and Ground to a new switching power supply. The monitor does not need an isolating transformer. I wired a known working power supply to the game board's 20 pin along with the 4 pin. I turn everything on. The Games Family board makes fan sounds like a normal computer with the initial single beep and the fast fan test before evening out. I wait the 90 seconds for a game list... nothing. Monitor shows absolutely nothing. I see no obvious switch or jumper to switch from vga to cga or even 25k. But if I put the 60 in 1 into the Jamma harness, it shows video right away.

Help!