A coil does not fire though its driver tests good and it has 43 V.

One coil dead with a good transistor and power at the coil

Cause: A bad or intermittent connector at the solenoid driver board.

Checks

• Check continuity from the coil to its SDB connector pin.

Fix

• Repin the connector or reflow the header.

Systems

• Bally MPU AS-2518-17
• Bally MPU AS-2518-35

Related tips

• Check the wire from a coil back to the solenoid driver board
• Solenoid driver board J3 pin functions
• Fire a coil by grounding its driver transistor tab (game on)
• Test solenoid driver transistors with the game off
• No coils work at all
• Test the 1N4004 diode behind a driver transistor
• Solenoid driver board: transistor, diode, resistor and connector for each driver
• Flippers dead though fuses and EOS switches are good

Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Three, Clay Harrell (pinrepair.com)