Score displays show only three of their six (or seven) digits.

Displays show only every other digit ("0_0_0")

Cause: Not the display board: a failing PIA on the driver board, either IC10 (lamps) or IC5 (solenoids) or both. The Leon test EPROM often passes these PIAs anyway.

Checks

• Swap or replace IC10 and IC5.

Fix

• Replace the failing PIA.

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7

Related tips

• Damage after the black and white plugs were swapped
• Test the driver board PIAs IC5, IC10 and IC11 with Leon's code
• CPU locks up as soon as the driver board is connected
• Test the switch PIA IC11 with the Leon test EPROM
• F-14 Tomcat: left credit-display character scrambled
• Odd DMD screens or "command 9c" errors with matching ROMs
• Three flashes only: U10 PIA
• Segments missing or stuck on: CPU board PIAs 9B and 7B

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)