Fitting a replacement coil on System 11

Steps

• On Big Guns and later, every coil except the flippers has its diode on the auxiliary power driver board: you may cut the diode off a new coil and connect the wires to either lug.
• If you leave the diode on such a coil, wire it the right way round; a reversed coil diode can still damage the driver transistor.
• On Fire! and earlier, the ground (usually thinner) wire must go to the lug at the non-banded end of the diode and the power wire to the banded end; reversed wiring shorts and destroys the diode.

Systems

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

Related tips

• 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
• Where the coil diodes are on System 11
• 50 V coils on early System 11: under-playfield relay boards
• 50 V coil dead on an early System 11 game
• Checking for power at a coil

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