A guy from here used to make mame cabinets with this kind of pc2jamma cards. Apparently he made them, but I'm not sure if he designed them.
There are three connectors at the end of the cable, VGA connector with 5 wires going in it, keyboard connector with 4 wires and audio jack. The wires from the VGA connector go directly to the pins of the card, the small chip on the left is for the sound and everything else is a keyboard encoder. The microcontroller in the middle is a PIC16F84A.
I guess I can draw the layout, but I was wondering if anyone have the schematics for this.