Against my better judgement, I offered to help repair a Bally Truck Stop for a friend. It powered up and displays looked good at his storage unit but it had a missing transistor at Q18.
Drove it 5 min across town, set it up, pulled the MPU and replaced the missing transistor. The game now plays well, however, my displays are now blank with "8" in each of the four sections.
I can faintly see the correct info displayed at random times. But these number "8"s over power everything.
Also if i disconnect the display connector at J2, the 8s are still present.
Voltages on the power supply all test within spec.
Any ideas what happened?? Thanks