A switch, or several switches together, do not show in switch test.
One switch or a string of switches never registers
Cause: Dirty contacts or a broken wire for a single switch; a break near the start of a daisy-chained row or column wire for a group; a broken pin or wire at MPU connector J2 (upper right); or an open switch diode.
Checks
- Check the contacts and wiring of a single dead switch.
- For a group, follow the shared wire back from the first dead switch.
- Inspect the J2 connector pins and the wires in the housing.
Fix
- Clean or adjust the contacts, repair the wire or repin the connector.
Systems
Related tips
- Switches register with the wrong numbers
- Tilt doesn't work and closing it fires a pop bumper: dirty slam tilt switch
- Closing one switch kills the whole column: slam tilt switch touching the coin door
- Several playfield switches drop out together: worn insulation shorting the start button
- Pop bumper and both outkicker switches dead: bare wire touching the coin door
- Stand-up target always closed in test and ghosting another: failed switch capacitor
- Clear stuck switches using switch test
- What bad switch diodes do to the matrix
Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Three, Clay Harrell (pinrepair.com)