Originally from Neo Geo Dev wiki, provided here for convenience.
JAMMA Edge
| Top
|
Pin
|
|
Pin
|
Bottom
|
| GND |
1 |
|
A |
GND
|
| GND |
2 |
|
B |
GND
|
| +5V |
3 |
|
C |
+5V
|
| +5V |
4 |
|
D |
+5V
|
| Unused |
5 |
|
E |
Unused
|
| +12V |
6 |
|
F |
+12V
|
| Key |
7 |
|
H |
Key
|
| Coin counter 1 |
8 |
|
J |
Coin counter 2
|
| Coin lockout 1 |
9 |
|
K |
Coin lockout 2
|
| Audio Right |
10 |
|
L |
Audio Left
|
| Mono audio out |
11 |
|
M |
Test button
|
| Video Red |
12 |
|
N |
Video Green
|
| Video Blue |
13 |
|
P |
Video Sync
|
| Video GND |
14 |
|
R |
Service button
|
| Coin #3 (P1) |
15 |
|
S |
Coin #4 (P2)
|
| Coin #1 (P1) |
16 |
|
T |
Coin #2 (P2)
|
| Start |
17 |
|
U |
Start
|
| Up |
18 |
|
V |
Up
|
| Down |
19 |
|
W |
Down
|
| Left |
20 |
|
X |
Left
|
| Right |
21 |
|
Y |
Right
|
| Button A |
22 |
|
Z |
Button A
|
| Button B |
23 |
|
a |
Button B
|
| Button C |
24 |
|
b |
Button C
|
| Button D |
25 |
|
c |
Button D
|
| Select |
26 |
|
d |
Select
|
| GND |
27 |
|
e |
GND
|
| GND |
28 |
|
f |
GND
|