Yes i have tried other boards. I was fixing a sound board on a NBA Jam TE board. I put back my orginal nba jam te board back in and it does the same.
I was putting in a new board in my jamma cab. I had the sound card plugged in the wrong way on main board, so I turned cab off and re hooked up sound card. When I plugged back in i heard the sound for like 3 sec and cab went dark. I looked at fuses all are good. Monitor still powers up but that is it, no ligts on coin or marq. On the board when I turn it on the red light on board comes on a little but goes out.
I think i am going to buy a new power supply and start there. One + on this you learn a lot from a mistake

...may cost you a bit though

Thanks for any help!!