Using a Taxi/Police Force display board in another 16-digit game

To use a Taxi/Police Force board in another 16-digit alphanumeric System 11 game, fit the seven missing resistors at R62-R68. To use a BK2000 board in Taxi, add U3 (UDN6118) and 10k resistors R9-R13 and R15-R18, and remove R54, R56, R57, R60, R62, R64, R65 and R67.

Systems

• Williams System 11B
• Williams System 11C

Games

• Black Knight 2000
• Police Force
• Taxi

Related tips

• One six-digit display completely dead
• Alphanumeric segments still missing: the UDN chips
• Left and right 16-character display boards are not interchangeable
• Same segment missing on every digit of one display: loose glass lead
• Same character position dead on every display: digit strobe wire at MPU J2
• Police Force car motor uses two drivers
• Check every segment with the display test
• Same segment missing across one 16-digit display

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