[header] How to connect a jamma harness [title] First thing you need is a jamma harness. [step] This is a standard edge connector with two rows of 28 pins used on almost all arcade machines. [title] The jamma harness has a standardised wiring code as follows : [step] The connector and board are usually' keyed' at the place where pin 7 would be, so that they will only go on one way. 
Sometimes the connectors are not keyed and it is possible to put it on the wrong way around. [title] Physically push the connector onto your jamma board.