Checking for power at a coil

Steps

• Raise the playfield and power the game up, leaving it in attract mode.
• Set the meter to DC volts (100 V range or higher) and put the black probe on the metal side rail.
• Touch the red probe to each lug of the coil (all three on a flipper coil): expect about 25 to 80 V DC on every lug.
• Voltage on one lug but not another means a broken winding; repair it or replace the coil.
• No voltage on any lug may mean an A/C bank coil: enter diagnostics, which drops the relay to bank A, or ground the Q7/Q8 tab, and measure again.
• Still none: check the fuse and trace the power wire back, since power is daisy-chained from coil to coil and one break kills every coil after it.

Solenoid voltage up to about 80 V DC is present on the coil lugs with the game on.

Systems

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

Related tips

• Testing coil diodes on the auxiliary power driver board
• What a bad coil diode does
• Fit coil diodes with the band on the power lug
• System 11 coil outputs
• 50 V coils on earlier System 11 games
• What changes when fixing coils on System 11
• Old Williams SA/SG 23-850 coils and their AE/AL replacements
• Coil sleeve part numbers by use

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