Tank Pinouts
Kee Games, August 1974

I believe these two boards are tightly back-to-back, and the edge connector
on each forms a single, double-sided edge connector.  The manual warns that
the two boards should not be pried apart.

                      Board I (J-3) |  Board II (J-6)
------------------------------------|--------------------------------------
        (From Transformer?) Gnd | 1 | 1 | Gnd (Left Joysticks Common)
--------------------------------|---|---|----------------------------------
                        LO - AC | 2 | 2 | Analog Gnd (to J-3, pin 7)
--------------------------------|---|---|----------------------------------
                        LO - AC | 3 | 3 | (Not Used)
--------------------------------|---|---|----------------------------------
                        HI - AC | 4 | 4 | (Not Used)
--------------------------------|---|---|----------------------------------
                        HI - AC | 5 | 5 | (Not Used)
--------------------------------|---|---|----------------------------------
     (Speaker 1 & 2 Common) Gnd | 6 | 6 | (Not Used)
--------------------------------|---|---|----------------------------------
          (from J-6, pin 2) Gnd | 7 | 7 | (Not Used)
--------------------------------|---|---|----------------------------------
                     (Not Used) | 8 | 8 | (Not Used)
--------------------------------|---|---|----------------------------------
                            Ant | 9 | 9 | (Not Used)
--------------------------------|---|---|----------------------------------
                            +5V |10 | 10| P2 Left Joystick, Down
--------------------------------|---|---|----------------------------------
                    Coin 2 - NC |11 | 11| P2 Right Joystick, Down
--------------------------------|---|---|----------------------------------
                    Coin 2 - NO |12 | 12| P2 Left Joystick, Up
--------------------------------|---|---|----------------------------------
                    Coin 1 - NC |13 | 13| P2 Right Joystick, Up
--------------------------------|---|---|----------------------------------
                    Coin 1 - NO |14 | 14| (Not Used)
--------------------------------|---|---|----------------------------------
                           -12V |15 | 15| P1 Left Joystick, Down
--------------------------------|---|---|----------------------------------
                     Speaker 2+ |16 | 16| P1 Right Joystick, Down
--------------------------------|---|---|----------------------------------
                     Speaker 1+ |17 | 17| P1 Left Joystick, Up
--------------------------------|---|---|----------------------------------
                     (Not Used) |18 | 18| P1 Right Joystick, Up
---------------------------------------------------------------------------
                     (Not Used) |19 | 19| P2 Button
--------------------------------|---|---|----------------------------------
                   Coin Counter |20 | 20| P1 Button
--------------------------------|---|---|----------------------------------
     (Speaker 1 & 2 Common) Gnd |21 | 21| Video
--------------------------------|---|---|----------------------------------
        (Coin 1 & 2 Common) Gnd |22 | 22| Gnd (from Video)
---------------------------------------------------------------------------

AC Power @ 110V/60Hz, stepped down to 6.3V

Is the AC Power only used for powering the B/W television?

I have no idea what "Ant" is.  The schematic doesn't show it going to
anything.