One or more displays show nothing at all although plus and minus 100 V are present.
Display completely dark with high voltage present
Cause: Outgassed display glass: age and high voltage contaminate the gas so it no longer glows. Glass can also short and blow the HV fuse.
Checks
- With the game on, look for tiny bright sparkles in the glass.
- Look for white dust near the two small wires below the viewing area.
Fix
- Replace the display glass; it cannot be repaired.
- Lower the supply to 91 V to protect the remaining glass.
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 3
- Williams System 4
- Williams System 6 / 6A
- Williams System 7
- Williams System 9
- Williams System 11
- Williams System 11A
- Williams System 11B
- Williams System 11C
Related tips
- Displays have high voltage but stay blank
- Score displays weak, dim or dead with fuses good
- Display high voltage out of range
- One segment lit on many characters of the top display: unsoldered leg on a driver chip
- High-voltage fuse blows once the display connector is plugged back in
- Lower the display voltage to 91 V to extend display life
- Williams System 3-7: all displays dead after replacing the 7180 driver: fake chip
- Same character position dead on every display: digit strobe wire at MPU J2
Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell