LED6 (TP8) is out and the controlled lamps are dark.

Driver board LED6 off: lamp matrix 18 V missing (WPC-S and earlier)

Cause: Fuse F114, bridge BR1 or capacitors C6 and C7. The 18 V also feeds the 12 V regulator Q2 (LM7812) for the switch matrix.

Checks

• Check F114, BR1, C6 and C7; measure TP8.

Fix

• Replace the failed part.

Systems

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

Related tips

• Driver board LED6 off (+18 V lamp matrix)
• Driver board LED1 off: switch matrix 12 V missing (WPC-S and earlier)
• Bridge rectifiers to use on WPC-S and earlier driver boards
• Bridge positions on WPC-S and earlier driver boards
• Driver board LED4 off and the game won't boot (WPC-S and earlier)
• WPC-89/WPC-S driver board LEDs and test points
• Voltages made by the WPC power driver board
• Supplies made on the WPC power driver board

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