Wire an A-16890 relay coil to run on EM AC power

Steps

• Keep the 1N4004 diode already fitted across the A-16890 coil.
• Move the game's BLACK coil wire(s) to the coil lug that has the diode's plain (anode, unbanded) end.
• Solder a second 1N4004 with its banded (cathode) end on the other coil lug.
• Connect the game's relay signal wire to the free, unbanded end of that added diode. The two diode bands now face the same coil lug.
• Test: the relay should pull in cleanly. Without the diodes it chatters and won't hold.

This half-wave rectifies the AC for just this relay. Gottlieb's own version adds a 50 uF 50 V capacitor across the coil (its + lead to the banded side) and a 6 ohm 2 W resistor ahead of the added diode; the guide's author found both unnecessary.

Systems

• Electro-mechanical

Related tips

• Relay coils used on System 80 games
• Coil diode and wire orientation when replacing a coil
• Check every coil's resistance before first power-up
• Check every coil's resistance before first power-up
• Testing coil diodes on the auxiliary power driver board
• Testing a coil diode
• Testing the diode on a coil
• Which way a coil diode goes

Source: Repairing Electro-Mechanical (EM) Coin Operated Games to 1978, Part Two, Clay Harrell (pinrepair.com)