> The problem is that since the controller lines are multiplexed, it wont work on JAMMA > without either hacking the controller or building a board to adapt it. Using various > connectors isn't going to do anything for you. Each input pin on the JAMMA connection > is sitting at 5v and you have to ground it for the board to see it as pressed.
There was a jamma to scart/megadrive pad board that could be picked up quite cheap off ebay a while back. It has two PIC chips for converting mega drive pads to jamma. If you can find one then thats probably the easiest.