JAMMA stands for Japanese Arcade Machine Manufacturers Association, a set of standards developed for board pinouts. This was designed to make board changes easy, just take out the old game and plug in the new.
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.
Jamma connector pinout
|Solder Side||Parts Side|
|Meter 2||J||8||Meter 1|
|Lockout 2||K||9||Lockout 1|
|Speaker -||L||10||Speaker +|
|Audio Ground||M||11||Audio +|
|Video Green||N||12||Video Red|
|Video Sync||P||13||Video Blue|
|Service Switch||R||14||Video Ground|
|Tilt Switch||S||15||Test Switch|
|Coin 2||T||16||Coin 1|
|2 Player start||U||17||1 Player 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|
|(Player 2 Button 4)||c||25||(Player 1 Button 4)|
|Not used||d||26||Not used|
- All input pins need ground to be activated (active low).
- Key 7/H says no connection because there is usually a piece of plastic placed in to this spot which will line up with a slot cut in the PCB. This is to prevent any chance of the connector being put on upside-down.
- Coin counter 1 "8" and coin counter 2 "J" are outputs. This is a mechanical style counter that increments every time a coin is inserted.
- Coin Lockout 9/K are outputs. This delivers power to a plunger activated by a solenoid which, when engaged into the coin path of the coin mech, will prevent a valid coin from tripping the coin switch and send it to the coin return slot. When power is fed to the coin door, an electromagnet retracts the plunger so that the coin path becomes open. Few games have coin lockout software in them.
- Service Switch "R" puts 1 credit onto the game but does not increment the coin meter.
- Test "15" enables the test mode, if the PCB supports it and triggers the test mode software of the game.
- Tilt "S" like in pinball games AKA "Slam" switch. The switch is found on almost all coin doors and is a leaf switch with a weight on the tip of one of them. If you slam the game hard enough, the leaf switch will close. Almost no games have tilt software in them. Behaviour ranges from a screeching tone for a few seconds to resetting the entire game.
- Coin Switch 1 "16" and coin Switch 2 "T" are inputs. When coin is inserted, a Ground pulse is sent to this pin and credits the game.
- Speaker +/- "10/L" is mono. It does not need an external amp. The speaker +/- is for post-amp output directly to the speaker. Audio +/- "11/M" is for pre-amp outputs but is hardly ever used.
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 pcbs as a general rule, but there are some exceptions you must be aware of. For instance, the SNK 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 some CPS2 games.
The pins marked Key Slot are used to prevent improper conenction 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 are widely used.