One or more display voltages read low.

Display voltages low: display or HV section?

Cause: Either the display is faulty, or the controller's high voltage section is failing and can't supply the display's load.

Checks

• Unplug the display power connector and measure again. If the voltages come back to normal, the display or the HV section under load is at fault.

Fix

• Try a known good display, or rebuild the HV section.

High voltage present on the display connector.

Systems

• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• Negative HV low and display barely lights
• Dot matrix display supply voltages
• The two negative display voltages must be 12 V apart
• -125 V and -113 V read the same and the display is dark
• Gas discharge displays need high voltage
• Rebuilding the dot matrix high voltage section
• Dot matrix display power connector pinout and voltages
• Outgassed displays and the 5 V supply

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Three, Clay Harrell (pinrepair.com)