P20: 44-pin edge connector

        component side        solder side
        --------------        -----------
          +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
        --------------        -----------
          +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:
------

"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.