The -125 V (or -115 V) supply reads too high, around -140 V.

-125 V reads about -140 V

Cause: A broken trace in the HV section, burnt by heat.

Checks

• Check every HV section trace for continuity.

Fix

• Repair the broken trace.

High voltage section: work with the game unplugged.

Systems

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

Related tips

• +62 V collapses to about +12 V under load
• +62 V reads over 70 V
• -125 V and -113 V read the same and the display is dark
• Outgassed displays and the 5 V supply

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