Centipede Chaos ticket dispensers are controlled by the I/O board located in the back of the main cabinet, the replacement part number for the board is WE2034X.
The ticket run signal can be measured between the ticket run line and ground. The ticket run lines are located on the P4 connector at the following pins:
Player 1 - pin 13 violet/ white wire
Player 2 - pin 22 brown/ white wire
Player 3 - pin 31 black/ white wire
When reading a ticket run line referenced to ground (black wire) when the signal is present you will see ~5vdc. You can force the game to activate the ticket dispenser run lines by accessing the tests menu in the game programming and performing the "ticket dispenser test"
The game will disable the ticket run lines if it does not see a ticket notch return line from the ticket dispenser resulting in the game to show a tickets owed error on the screen.
The ticket notch lines when referenced to ground (black wire) will be high at ~5vdc and drop low to <1vdc when the notch on the ticket unblocks the optic on the ticket dispenser, if the line does not go below 1vdc the I/O board will not recognize the change in state.
The ticket notch lines can be located on the P4 connector at the following pins:
Player 1 - pin 12 white/blue wire
Player 2 - pin 21 grey/blue wire
Player 3 - pin 30 yellow/blue wire
All harness connection information can be found on the system schematic for the game.