This is a simple hack I did today to coin up my pacman and galaxian with the player two button. Anyone who owns these games knows that setting the games to free play negates the attract screen. I believe Mrs Pac and Galaxian are the same way. All you will need is a wire and some zip ties or electrical tape.
Step one. Make sure your dipswitch settings are set to 1 coin/1 play. 1 coin/2 plays can boink things up.
Step 2 : Locate the player 2 wire and note it's color.
Step 3: Locate the one of the coin up wires from the coin door and note it's color.
Step 4: Take a short pice of wire and strip both ends.
Step 5: On the cabinet side of the control panel interconnect shove one end of the wire into the hole where the player 2 wire terminates. You can take the pin out and crimp a new one with both wires if you wish, but simply shoving the wire in will work just fine, and it's simple to remove if you want.
Step 6: On the cabinet side of the coin door interconnect, shove the other end of the wire into one of the coin terminals.
Step 7: Zip tie or use electrical tape to secure both ends of the wire to the wire looms.
When you hit player 2 once you coin up. Hit it 3 times to add two credits and start a two player game.