No problem shows at rest, but closing a switch in one column also shows the switch on the same row in a second column (for example column 2 row 3 also shows column 4 row 3).
Pressing a switch also shows one in another column
Cause: Two column wires are shorted together.
Checks
- Note the two columns involved and look for where their wires touch, such as at a switch or harness pinch point.
Fix
- Separate and insulate the shorted wires.
Systems
Related tips
- Closing one switch shows its whole row closed
- False switch readings only when several switches are closed
- Switch row or column error: CPU board or playfield?
- Most switch matrix faults show up as row faults
- How Data East switch numbers map to rows and columns
- Pressing one switch closes the whole row: bad 4011 chip on the CPU board
- Whole switch column dead after working under the playfield
- A single switch does not register
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)