Where GI power flows on the driver board

Transformer GI wires enter at J115 (J103 on WPC-95), pass through the GI fuses (F106-F110; F110-F114 on WPC-95) and triacs, and leave on the GI output plugs, J120/J121 on WPC-89 and WPC-S or J105/J106 on WPC-95. GI lights only after the CPU boots, except the two non-triac strings on WPC-95, which light immediately.

Systems

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

Related tips

• Test GI outputs on the driver board
• Testing lamp-row drivers with a test lamp
• Testing lamp-column drivers with a test lamp
• WPC lamp matrix and GI driver parts
• J115 GI input pin map (WPC-89/WPC-S driver board)
• WPC power driver board versions and where they fit
• GI fuse keeps blowing: isolate driver board or wiring
• One GI string dead after a restoration: unkeyed J115 plugged in upside down

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