JAMMA connector pinout
MVS systems edge connectors aren't fully JAMMA compliant.
The pin pitch is .156in (3.96mm). There are 28 pins per side (key included), 56 total.
Many harnesses don't have the key to avoid accidentally plugging them backwards. Doing so will certainly fry the inputs chip (NEO-C1...).
Note that the G, I, O, and Q letters aren't used, to avoid confusion.
MVS pinout
| Bottom | Top | ||||
|---|---|---|---|---|---|
| GND | A | 1 | GND | ||
| B | 2 | ||||
| +5V | C | 3 | +5V | ||
| D | 4 | ||||
| Unused | E | 5 | Unused | ||
| +12V | F | 6 | +12V | ||
| Key | H | 7 | Key | ||
| Coin counter #2 | 
|
J | 8 | 
|
Coin counter #1 |
| Coin lockout #2 |
|
K | 9 |
|
Coin lockout #1 |
| Left speaker |
|
L | 10 |
|
Right speaker |
| Test switch |
|
M | 11 |
|
Mono audio |
| Video green |
|
N | 12 |
|
Video red |
| Video sync |
|
P | 13 |
|
Video blue |
| Service switch |
|
R | 14 | Video GND | |
| Coin switch #4 P2 |
|
S | 15 |
|
Coin switch #3 P1 |
| Coin switch #2 P2 |
|
T | 16 |
|
Coin switch #1 P1 |
| P2 Start |
|
U | 17 |
|
P1 Start |
| P2 Up |
|
V | 18 |
|
P1 Up |
| P2 Down |
|
W | 19 |
|
P1 Down |
| P2 Left |
|
X | 20 |
|
P1 Left |
| P2 Right |
|
Y | 21 |
|
P1 Right |
| P2 button A |
|
Z | 22 |
|
P1 button A |
| P2 button B |
|
a | 23 |
|
P1 button B |
| P2 button C |
|
b | 24 |
|
P1 button C |
| P2 button D |
|
c | 25 |
|
P1 button D |
| Select down |
|
d | 26 |
|
Select up |
| GND | e | 27 | GND | ||
| GND | f | 28 | GND | ||
Infos from [HardMVS.com]