A whole circuit, often all the lamps, is dead even though its fuse tests good.

All lights out but the fuse is good

Cause: The fuse clips are loose, broken or corroded and do not grip the fuse.

Checks

• Look at the fuse clips for tarnish, cracks or weak spring.
• With power off, check continuity from the wire on each clip to the fuse cap.

Fix

• Clean the clips and bend them for a tight grip, or replace the fuse holder.

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7
• Williams System 9
• Williams System 11
• Williams System 11A
• Williams System 11B
• Williams System 11C
• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95
• Bally MPU AS-2518-17
• Bally MPU AS-2518-35
• Stern MPU-100
• Stern MPU-200
• Bally 6803
• Gottlieb System 1
• Gottlieb System 80
• Gottlieb System 80A
• Gottlieb System 80B
• Gottlieb System 3
• Data East CPU Version 1/2
• Data East CPU Version 3
• Data East/Sega CPU Version 3b
• Capcom
• Electro-mechanical

Related tips

• Dead or intermittent circuit from a cracked fuse clip
• Testing a fuse
• Checking a fuse properly
• Where the fuses are
• No lamps, no coils or no power: tired fuse holder
• Fuse rating rules

Source: Pinball Machine Care & Maintenance, Bernard B. Kamoroff (Bell Springs Pinball Alley)