Fit 91 V zeners at Z2/Z4 to extend display life
Steps
- Remove the 100 V 1N4764 zeners at Z2 and Z4 in the high-voltage section.
- Install 1N4763 (91 V) zeners with the bands the same way.
- Expect slightly dimmer, longer-lasting score displays.
The display supply runs at about 100 volts DC; work with the game off and the capacitors discharged.
Systems
Related tips
- Change zener diodes Z2 and Z4 for longer display life
- Lower the display voltage to 91 V to extend display life
- Run alphanumeric displays at 91 V for longer life
- All score displays dead
- Score displays light then dim or flicker
- Parts for rebuilding the System 3-7 display supply
- Find a shorted display glass that blows F1
- Master display flickers, worst when showing 1: wrong zener diodes at ZR2 and ZR4
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part One, Clay Harrell (pinrepair.com)