LED6 is out and no matrix lamps light.

Driver board LED6 off (+18 V lamp matrix)

Cause: Fuse F114, bridge BR1 or capacitors C6/C7.

Checks

• Check F114.
• Measure TP8.

Fix

• Replace the failed fuse, bridge or capacitor.

Systems

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

Related tips

• Driver board LED6 off: lamp matrix 18 V missing (WPC-S and earlier)
• No lamp matrix lamps light
• Lamp matrix connectors on the driver board
• Driver board LED1 off: switch matrix 12 V missing (WPC-S and earlier)
• WPC-89/WPC-S driver board LEDs and test points
• Driver board filter capacitors wear out
• Voltages made by the WPC power driver board
• Bridge rectifiers to use on WPC-S and earlier driver boards

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