A column or two of the dot matrix display stays lit all the time.

One or two display columns stuck on

Cause: The 6264 RAM at U24 on the dot matrix controller board (WPC-S and earlier) has failed.

Checks

• Try the display in another game first to rule it out.

Fix

• Replace U24 with a new 6264 RAM.

Systems

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

Related tips

• Dot matrix display supply voltages
• Dot matrix display faults
• Dot matrix display blank or faulty
• Dot matrix display power connector pinout and voltages
• Resets caused by a failing dot matrix display
• What the WPC dot matrix controller does
• Game stuck showing the last four high scores
• Blank display, garbage or diagonal lines: reseat ribbon cables

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