All general illumination is out.

No GI at all

Cause: No 6.3 V AC reaching the driver board, or the 74LS374 GI latch.

Checks

• Measure the 6.3 V AC arriving from the transformer.
• Check the GI input connector for burning.
• Check the latch.

Fix

• Repair the transformer wiring or connector, or replace the latch.

Systems

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

Related tips

• General illumination strings
• GI string dead after connector replacement: broken traces
• Several GI strings dead after a connector repair: lifted pads at J115
• All GI out (playfield and backbox) with good fuses and plugs: reseat the CPU ASIC and ROM
• One GI string dead though the board and fuse test fine: burnt connector in the cabinet
• GI string still dead after replacing J115: broken through-hole, add a jumper
• One GI string dead after a restoration: unkeyed J115 plugged in upside down
• All backbox lights out with good fuses: burned J120 GI connector

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