Here’s a low cost, DIY solution for a custom JAMMA adapter. In this kit you will receive a 56 pin female edge connector and a conversion board. You supply your own wire, or as an option some can be included in the kit.
The adapter board includes a couple of solder shortcut pads for pins that are normally grounded on a JAMMA harness: SPK- and VGND.
Version 1.0: Initial Design. Obsolete now.
Version 1.1: Changed pad size. Added shortcut pads for VGND and SPK-.