Garbage on the dot matrix display, or no display, with good high voltages.

Display shows garbage or nothing though the glass is fine

Cause: Failed controller chips on the display's own board (static sensitive), lifted surface-mount parts, or cracked solder on the display's .156 inch power header pins.

Checks

• Inspect the display board for lifted parts and cracked power header joints.

Fix

• Reflow the power header if it can be reached past the glass, re-attach lifted parts, or replace the display.

Systems

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

Related tips

• Dot matrix display supply voltages
• Rebuilding the dot matrix high voltage section
• Dot matrix display blank or faulty
• Dot matrix display power connector pinout and voltages
• Dot matrix display faults
• Display misbehaves with good voltages: crystallised zener joints
• Gas discharge displays need high voltage
• Dot matrix display with dark gaps or dim areas: outgassed glass

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