GI lamps and matrix lamps

GI lamps light as soon as the game is switched on and normally stay on; only Blackout, Scorpion and System 7 games have a GI relay to switch them. Matrix lamps are controlled by the CPU in attract mode and play.

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7

Related tips

• No lamp matrix voltage
• Lamp matrix column test at 2J5 with Leon's code
• Lamp matrix row test at 2J7 with Leon's code
• Lamp matrix wire colours and connector pins
• A single lamp does not light
• Fixing the burnt lamp matrix resistors R149-R156
• Lamp numbers that are the same on most games
• All matrix lamps out, everything else works

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)