One of the lamp, unregulated 12 V, flasher or coil supply LEDs is out.

WPC-95 LED102, LED103, LED104 or LED105 off

Cause: LED102 (+18 V lamps): F106, D11-D14, C11/C12. LED103 (+12 V unregulated): F109, D3-D6, C8. LED104 (+20 V flashers): coin door open, F107, D15-D18, C10. LED105 (+50 V coils): coin door open, F108, D19-D22, C22.

Checks

• Close the coin door first; 104 and 105 go out by design when it is open.
• Check the matching fuse and measure the matching test point.

Fix

• Replace the fuse, diodes or capacitor for that supply.

Systems

• WPC-95

Related tips

• WPC-95: a dark +20 V LED at TP104 means the flasher supply is not leaving the board
• WPC flashers and coils all dead? Check the coin door interlock first
• WPC-95 driver board LEDs and test points
• WPC-95: all the 20 V coils dead, fuse good
• +20 V filter capacitor C11 (C10 on WPC-95) blows apart
• WPC-95 rectifier diodes, filter caps and fuses by supply
• Check fuses F106/F101 with no lamps and no game start: shorted bridge diode
• 12 V unregulated LED out on the driver board: open track to C8

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