An A-side coil does nothing in the solenoid test.

A-bank coil not working

Cause: Coil, wiring or driver fault on that output.

Checks

• Unplug 1J12 on the CPU/driver board so the bank relay cannot pull in and power stays on bank A.
• Briefly ground the coil terminal, then the driver transistor tab.

Fix

• Repair the coil, wiring or driver as found.

Systems

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

Related tips

• Whole groups of coils or all flashers dead: A/C select relay stuck
• Wrong coils fire together (A/C bank game)
• System 11 coil outputs
• How the System 11 A/C bank select works
• How System 11 special solenoids work
• How System 11 A/C switched solenoids work
• Where the coil diodes are on System 11
• Which output drives the bank select relay

Source: Pinball Machines: How They Work & Troubleshooting, Norbert Snicer