JAMMA stands for Japan Amusement Machinery Manufacturers Association, and is the groups that defined the standard connector known as a JAMMA harness for arcade pcbs.
The JAMMA wiring standard was introduced in 1985. Arcade cabinets wired to the JAMMA standard can be made to play all games built to this standard, simply by installing the circuit boards for the new game. By the 1990s, most new arcade games were JAMMA standard. As the majority of arcade games were designed in Japan at this time, JAMMA became the de facto world standard.
|Solder Side||Pin||Pin||Parts Side|
|KEY SLOT||H||7||KEY SLOT|
|COIN COUNTER #2||J||8||COIN COUNTER #1|
|LOCK OUT COIL #2||K||9||LOCK OUT COIL #1|
|SPEAKER (-)||L||10||SPEAKER (+)|
|N/C (Empty)||M||11||N/C (Empty)|
|VIDEO GREEN||N||12||VIDEO RED|
|VIDEO SYNC||P||13||VIDEO BLUE|
|SERVICE SWITCH||R||14||VIDEO GROUND|
|TILT (SLAM) SWITCH||S||15||TEST SWITCH|
|COIN SWITCH #2||T||16||COIN SWITCH #1|
|PLAYER 2 - START||U||17||PLAYER 1 - START|
|PLAYER 2 - UP||V||18||PLAYER 1 - UP|
|PLAYER 2 - DOWN||W||19||PLAYER 1 - DOWN|
|PLAYER 2 - LEFT||X||20||PLAYER 1 - LEFT|
|PLAYER 2 - RIGHT||Y||21||PLAYER 1 - RIGHT|
|PLAYER 2 - BUTTON 1||Z||22||PLAYER 1 - BUTTON 1|
|PLAYER 2 - BUTTON 2||a||23||PLAYER 1 - BUTTON 2|
|PLAYER 2 - BUTTON 3||b||24||PLAYER 1 - BUTTON 3|
|N/C (Empty)||c||25||N/C (Empty)|
|N/C (Empty)||d||26||N/C (Empty)|
When building a SuperGUN or when cabling a general purpose arcade cabinet it is important to adhere to the JAMMA standard. There are several connectors that are marked as N/C (Empty), these are not used by JAMMA pcb as a general rule, but there are some exceptions you must be aware of. For instance, the Neo Geo MVS has it's own standard based in JAMMA, but uses a couple of those Empty pins for the fourth button and the select game button. Even some Capcom games use pins c and 25 for a fourth player, such as the Dungeons & Dragons games.
The pins marked Key Slot are used to prevent improper connection which could lead to damage in the board due to voltage applied to signal lines.
When building a SuperGUN there is little use for the Coin counter, Coin Lockout and Tilt pins. But the Service and Test ones are widely used.