Gas discharge displays need high voltage

Gas discharge (plasma) displays glow only when high voltage is across the neon-filled tube, about +100 V and -100 V on System 11. With no high voltage the display stays blank even when the logic works.

The display supply runs at about +100 V and -100 V; switch off before touching the display or its driver board.

Systems

• Williams System 11
• Williams System 11A
• Williams System 11B
• Williams System 11C
• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• WPC alphanumeric display board high-voltage checks
• Dot matrix display supply voltages
• The two negative display voltages must be 12 V apart
• Display voltages low: display or HV section?
• Display shows garbage or nothing though the glass is fine
• High-voltage fuse blows once the display connector is plugged back in
• Rebuilding the dot matrix high voltage section
• Dot matrix display power connector pinout and voltages

Source: Pinball Machines: How They Work & Troubleshooting, Norbert Snicer