With nothing pressed the switch test is clear, but closing any switch in one column lights every switch in that switch's row.
Closing one switch shows its whole row closed
Cause: That column wire is shorted to ground somewhere on the playfield.
Checks
- Start at the end of the column wire chain and disconnect it from one switch at a time until the fault clears in the switch test.
Fix
- Repair the shorted point in the wiring.
Systems
Related tips
- Pressing a switch also shows one in another row
- False switch readings only when several switches are closed
- Pressing a switch also shows one in another column
- Whole switch column dead after working under the playfield
- Pressing one switch closes the whole row: bad 4011 chip on the CPU board
- How Data East switch numbers map to rows and columns
- One switch column dead: parts to check in order
- One switch row dead: parts to check in order
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)