After converting the up-kicker to a pop bumper driver board, it kicks whenever a flipper button is pressed.
Up-kicker fires by itself when the flippers are pressed
Cause: The trigger line from the CPU side picks up electrical noise; an original Gottlieb driver board has no filtering on that input.
Checks
- Look on the solder side of the board for a capacitor between connector pins 4 and 5.
Fix
- Fit a 4.7 uF 10 V electrolytic: negative leg to pin 4 (trigger), positive leg to pin 5 (+5 V).
Systems
Games
Related tips
- Black Hole up-kicker on a pop bumper driver board
- Haunted House up-kicker too weak to reach the main playfield
- Game won't boot, or keeps rebooting, because of the reset board
- How the pop bumper driver board fires its coil
- Black Hole up-kicker rarely needs the driver board conversion
- Add power and fire LEDs to a pop bumper driver board
- Pop bumper fires erratically or several times
- How the System 80 pop bumper driver board works
Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part Two, Clay Harrell (pinrepair.com)