Some or all character positions on a display are blank in display test.

Characters missing from a display

Cause: A failed UDN6118 digit driver; one bad leg blanks one character position, a dead chip blanks many (all of one display on pre-Taxi games).

Fix

• Replace the UDN6118 for those positions.

Systems

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

Related tips

• UDN display driver chips
• UDN display driver chips
• Segment missing or stuck only on certain characters
• System 9 versus System 11 display data
• Display board chips shown as 4050 are really 4049
• Telling a shorted UDN chip from a shorted display glass
• One segment lit on many characters of the top display: unsoldered leg on a driver chip
• Displays dead after the CPU board was removed

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