LED4 (TP2) on the power driver board is out and the game won't boot.

Driver board LED4 off and the game won't boot (WPC-S and earlier)

Cause: The +5 V supply is missing: fuse F113, bridge BR2 or capacitor C5. Less likely, the LM323 regulator at Q1. Power enters on J101 pins 1 and 2 and leaves on J114 pins 3,4.

Checks

• Measure TP2 against TP5 (ground).
• Check F113, BR2 and C5.

Fix

• Replace the failed part.

Systems

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

Related tips

• Voltages made by the WPC power driver board
• Bridge rectifiers to use on WPC-S and earlier driver boards
• Supplies made on the WPC power driver board
• Driver board LED4 off (+5 V missing, game will not boot)
• Bridge positions on WPC-S and earlier driver boards
• WPC power driver bridge rectifiers and +5 V regulator
• WPC-89/WPC-S driver board LEDs and test points
• Driver board LED6 off: lamp matrix 18 V missing (WPC-S and earlier)

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