Why WPC GI comes on only after boot

WPC general illumination is switched by triacs on the driver board under CPU control, so the GI stays off until the game has finished booting. On WPC-95 the backbox GI is not triac controlled: it lights at once at power-on and always runs at full brightness, while the playfield GI still waits for boot.

Systems

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

Related tips

• WPC-95 LED101 off (+5 V, game will not boot)
• Bulbs to keep on hand for WPC games
• How the WPC lamp matrix works
• The three WPC lamp circuits
• How the WPC lamp matrix is switched
• WPC lamp matrix and GI driver parts
• Lamp matrix wire colors (all WPC games)
• J115 GI input pin map (WPC-89/WPC-S driver board)

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