Check every segment with the display test

Run the display test to see that every digit and segment lights. If one fails, first make sure all display connectors are fully seated; most remaining faults are on the display driver board and need bench repair.

Systems

• Williams System 11
• Williams System 11A
• Williams System 11B
• Williams System 11C

Related tips

• System 11 alphanumeric displays
• Displays blank but the game plays
• System 9 versus System 11 display data
• UDN display driver chips
• Check the segment resistors before buying a UDN7180
• Same segment missing across one 16-digit display
• Score display layouts across System 11
• Lower the display voltage to 91 V to extend display life

Source: Pinball Machines: How They Work & Troubleshooting, Norbert Snicer