Coils on solenoids 1-8 do nothing (relay stuck on bank C), or the bank C flashers never work (relay stuck at rest on bank A).

Whole groups of coils or all flashers dead: A/C select relay stuck

Cause: A relay held on bank C is usually caused by a shorted Q7/Q8 driver. A relay that never pulls in points to its driver, its wiring or the relay.

Checks

• With the game in attract or diagnostics, clip a lead from the backbox ground strap to the tab of the relay driver (Q7 on Fire! and earlier, Q8 from Big Guns); the relay on the power supply or auxiliary board should click.
• If it does not click, turn the game off and check Q7/Q8 tab to ground on continuity; a beep means a shorted transistor.

Fix

• Replace a shorted Q7/Q8 (TIP102).
• If the transistor is good, see the A/C relay entry for the relay itself.

Systems

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

Related tips

• Whole A or C bank of coils dead
• C-bank coil or flasher not working
• A-bank coil not working
• Wrong coils fire together (A/C bank game)
• How the System 11 A/C bank select works
• Special solenoids dead after fitting an early System 11 CPU in a later game
• Controlled solenoids 9-16
• How System 11 A/C switched solenoids work

Source: Repairing Williams System 11 Pinball 1986 to 1990, Deel 1, Clay Harrell (pinrepair.com)