A single switch is always shown closed while everything else works.
One switch shows closed though it is open
Cause: Its column wire and row wire are shorted together somewhere; the switch shown is not itself the cause.
Checks
- Trace both wires for a point where they touch.
Fix
- Separate and insulate the wires.
Systems
Related tips
- A single switch does not register
- An entire switch row shows closed all the time
- Closing one switch shows its whole row closed
- Using the test EPROM burn-in to find closed switches
- Most switch matrix faults show up as row faults
- Pressing one switch closes the whole row: bad 4011 chip on the CPU board
- Whole switch column dead after working under the playfield
- Pressing a switch also shows one in another column
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)