Wiring PC PSU to Credit broad?

[lettuce]

Do i need to hook my Credit board (Shefras Green Board) up to my PCs PSU if i want it to work with mame? I notice there is a yellow +12v wire and seems to be 2 black wires connected to the board, but i think only one of them is for ground. So i guess i need to hook the yellow wire up to thr yellow wire of the PCs PSU, but the PSU has, a red, 2 black, and yellow wire, so which one of these black wires from the PC PSU is the ground wire?

[testicle187]

Both of the black wires coming from the PCs PSU are ground wires.  Just connect it to the one nearest the yellow wire. 

[lettuce]

Ok cheers, i think both black wires on the credit broad are both GND too. what i have noticed is the coin light is +5V as it has a black and red wire conected to it, is the coin light usually +5v?, could i not connect this to my JPAC connection?