Have a Star Trek that has display problems related to the MPU, as I swapped out the MPU and the problem went away. I'd like to get the original board fixed.
Symptoms of the bad board. When in attract mode the 4 player displays each show 00. When I press the credit button to start a game the #1 player display goes blank, and the 1's digit on player 3 goes blank. When I play the ball and start scoring points, the #1 display shows the points incrementing, then when the ball drains and the bonus is collected, the digits go blank again until the start of the second ball, except for the 1's and 10's digits. Weird. This continues all throughout the game.
I have ruled out connectors and power supply. I have 170 volts to each display. Everything else on the game seems to work fine (except for some GI lamps out). Any thoughts on what is wrong with the MPU?