The displays reveal three or four digits at a time across each display in turn and never show a whole display at once, though scoring is correct.

Displays show only three or four digits at a time in a slow wipe

Cause: Weak high voltage, sometimes as low as 50 V: R1/R4 (39k) drifted, or a bad C1/C3 (100 uF 250 V) or C2/C4 (0.1 uF 250 V) on the power supply.

Checks

• Measure the plus and minus 100 V supplies.

Fix

• Replace R1/R4 and the high-voltage capacitors as needed.

The display supply runs at about 100 V DC (plus and minus) with large filter capacitors; work with the game off and unplugged, and measure live only with insulated probes.

Systems

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

Related tips

• Rebuilding the +100 V section of the power supply
• Rebuilding the -100 V section of the power supply
• Display correct but too bright or flickering
• High-voltage fuse blows once the display connector is plugged back in
• Displays blank but the game plays
• Lower the display voltage to 91 V to extend display life
• Score displays weak, dim or dead with fuses good
• "IRQ Failure" at power-on

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