Hitting either left pop bumper tilts the game. In switch test, closing a pop bumper switch shows every switch in that row as closed, including a tilt switch.
Hitting the left pop bumpers tilts the game: failed PIA on the MPU
Cause: A PIA chip on the MPU board that reads the switch matrix had failed. The coil diodes, switch capacitors and tilt switches were all fine.
Checks
- Check the diode on every switch in the affected row first.
- Unplug the switch matrix connectors and jumper rows to columns at the board to see whether the fault is on the board or the playfield.
Fix
- Replace the faulty PIA on the MPU board (socket it while you are there).
Systems
Games
Related tips
- Pop bumpers do not show in switch test: pull the ring down to test them
- Hitting a pop bumper resets the drop targets: faulty pop bumper coil
- Switch column or row fault on the driver board
- Switches stuck on: board or playfield?
- System 6: game stuck in tilt with switch 1 closed: cracked pins in the 2J2 plug
- Replacement MPU shows two solid red LEDs after setup: DIP switches set upside down
- The switch test cannot check pop and sling trigger switches
- A drop target switch registers when the lower pop fires: replace the pop coil
Source: Pinball Repair help group!! (Facebook group)