A whole row shows as closed in the switch test whether or not any switch is pressed.
An entire switch row shows closed all the time
Cause: The row wire is shorted to ground, either at the plain (anode) end or the banded (cathode) end of a switch diode.
Checks
- From the end of the row chain, disconnect one switch at a time until the row clears in the switch test.
Fix
- Repair the short to ground.
Systems
Related tips
- Most switch matrix faults show up as row faults
- Whole switch column dead after working under the playfield
- Pressing one switch closes the whole row: bad 4011 chip on the CPU board
- One switch row dead: parts to check in order
- One switch shows closed though it is open
- A single switch does not register
- Pressing a switch also shows one in another row
- False switch readings only when several switches are closed
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)