P20: 44-pin edge connector
component side solder side
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+5VDC RETURN A 1 +5VDC RETURN
+5VDC B 2 +5VDC
C 3 +22VDC
D 4 -22VDC
COIN R E 5 SLAM
COIN C F 6 COIN L
DIAG STEP H 7 SELF TEST
X INV J 8 OUT 5 (not used)
Y INV K 9 BLUE
GREEN L 10 RED
VIDEO GND M 11 MONOCHROME VIDEO
COIN CTR R N 12 COIN CTR L
COIN CTR C P 13 PWR GND
PWR GND R 14 +10.3 VDC UNREG
Y INVERT S 15 X INVERT
X OUT T 16 X GND
Y GND U 17 Y OUT
~RESET V 18 E (2.4 kHz clock)
-22VDC W 19
+22VDC X 20
+5VDC Y 21 +SENSE (+5V)
+5VDC RETURN Z 22 -SENSE (GND)
C, D, 19 & 20 appear to be unused
P18: 30-pin edge connector
component side solder side
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+5VDC RETURN A 1 +5VDC RETURN
+5VDC B 2 +5VDC
~COCK C 3 +22VDC
AUDIO- D 4 -22VDC
AUDIO- RETURN E 5 AUDIO+
~RESET F 6 AUDIO+ RETURN
CLK1 H 7 CLK2
DIR1 J 8 DIR2
FIRE2 K 9 FIRE1
ZAP2 L 10 ZAP1
P2 START M 11 P1 START
-22VDC N 12 P1 LED
+22VDC P 13 P2 LED
+5VDC R 14 +5VDC
+5VDC RETURN S 15 +5VDC RETURN
Notes:
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"RETURN" pins are ground, but specifically for the voltages indicated.
Ground ~COCK if you're installing in a cocktail table, and connect X INV to X INVERT and Y INV to Y INVERT. Hook up a 2nd set of controls to CLK2, DIR2, FIRE2 and ZAP2 and the game will "flip" for 2 player games.