Power supply fuse F5 or F6 (7 A slow-blow) blows immediately every time the game is turned on.

+5 V fuse blows the instant the game is switched on

Cause: The +5 V logic bridge, BR1 on the power supply, has shorted.

Checks

• Replace the fuse once; if it blows again at once, BR1 is shorted.
• With the game off, test BR1 in diode mode.

Fix

• Fit a new BR1 (35 A 200 V, wire leads for board mounting) and replace filter capacitor C10 at the same time.

Systems

• Williams System 11
• Williams System 11A
• Williams System 11B
• Williams System 11C

Related tips

• Resets continue after diode repair: power and connector checks
• Choosing replacement bridge rectifiers
• What the System 11 power supply board feeds
• Rebuilding the +100 V section of the power supply
• Rebuilding the -100 V section of the power supply
• GI connectors left the power supply after Cyclone
• System 11 power supply versions D-8345 and D-12246
• Routine high-voltage changes on every System 11 power supply

Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Two, Clay Harrell (pinrepair.com)