System 4 fuse chart

Power supply: F1 display 90 VAC 1/4 A slow; F2 solenoids 28 VDC 2.5 A slow; F3 lamp matrix 18 VDC 8 A fast; F4 unused before Flash, then the 10 A fast flipper fuse; F5 +5 V logic 4 A fast. Sound board F1 and F2 9.3 VAC 4 A slow. Fuse card: 6.3 V GI 20 A fast. Under the playfield (before Flash): flippers 10 A fast.

Systems

• Williams System 4

Related tips

• Fuse values to keep on hand for System 3-7
• Main line fuse for System 3-7
• Testing a fuse
• Where the flipper fuse is by generation
• Add fuses to the inputs of the backbox bridges
• Pull the coil and lamp fuses for the first power-up
• Pull fuses F2 and F3 until the CPU board runs properly
• Solenoid fuse blows as soon as the game is turned on

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