Nothing shows at rest, but closing a switch in one row also shows the switch in the same column on a second row.
Pressing a switch also shows one in another row
Cause: Two row wires are shorted together.
Checks
- Note the two rows and look for where their wires touch.
Fix
- Separate and insulate the wires.
Systems
Related tips
- Closing one switch shows its whole row closed
- False switch readings only when several switches are closed
- Most switch matrix faults show up as row faults
- How Data East switch numbers map to rows and columns
- Switch row or column error: CPU board or playfield?
- An entire switch row shows closed all the time
- Pressing one switch closes the whole row: bad 4011 chip on the CPU board
- Whole switch column dead after working under the playfield
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)