Pressing a flipper button no longer changes the lit lanes (or enters initials).

Lane change not working on Taxi and later System 11 games

Cause: From Taxi on, the interconnect board senses the flipper buttons through an optoisolator: a MOC3010 (NTE3047) on Taxi and a 4N25 (NTE3040) from Jokerz on. These chips fail, and burnt interconnect connector pins or burnt 50 V solenoid traces also stop them working.

Checks

• Inspect the interconnect board connectors for burnt pins.
• Look for burnt traces on the 50 V solenoid lines on the board.

Fix

• Replace the small optoisolator chip (MOC3010 on Taxi, 4N25 on Jokerz and later).
• Repin burnt connectors and repair burnt traces.

Systems

• Williams System 11B
• Williams System 11C

Games

• Bad Cats
• Black Knight 2000
• Bugs Bunny's Birthday Ball
• Diner
• Dr. Dude And His Excellent Ray
• Elvira and the Party Monsters
• Jokerz!
• Mousin' Around!
• Police Force
• Pool Sharks
• Radical!
• Riverboat Gambler
• Rollergames
• Taxi
• The Bally Game Show
• Transporter the Rescue

Related tips

• Upper right flipper only buzzes while the magnet holds the ball: failed opto-isolator
• The interconnect board (Banzai Run and later)
• Pre-Fliptronics: flipper lane change does not work
• Flipper buttons not seen by the game (pre-Fliptronics)
• Funhouse: flipper buttons won't step through high score initials
• Phantom switch closure that survives a new CPU board: bad 4N25 on the driver board
• WPC: phantom switch closures traced to a 4N25 on the -1 driver board
• Row or column "ground short" errors

Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell