Special solenoid trigger test at 2J12/2J13

Steps

• Ground any pin of 2J10 (or leave the game connector on it). 2J12 pin 2 is the flipper return and is not tested.
• Tester LED on 2J12 pin 3 with 2J13 pin 2 grounded; pin 4 with 2J13 pin 3; pin 6 with 2J13 pin 4; pin 7 with 2J13 pin 5; pin 8 with 2J13 pin 8; pin 9 with 2J13 pin 9. Each should blink.
• If one stays on or off, keep the LED in place and move the ground back through the circuit: from the 2J13 pin to IC6 pins 11, 8, 6, 3 or IC7 pins 11, 8. If it now blinks, IC6 or IC7 is bad.
• Then move it to IC8 pins 4, 13, 10 or IC9 pins 1, 4, 13. If it now blinks, IC8 or IC9 is bad.
• Still no blink: suspect the 2N4401 pre-driver (odd numbers Q1 through Q11) or the TIP120/TIP102 driver (even numbers Q2 through Q12).

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7

Related tips

• CPU-controlled and special solenoids
• Pop or sling works in the game but not in test, or the reverse
• A cracked coil diode keeps killing its driver transistor
• Coil outputs available on System 3-7
• The coin lockout coil is meant to be on
• Pop bumper or slingshot locked on
• Check the wire from the coil to its driver transistor
• Special solenoid control paths

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Two, Clay Harrell (pinrepair.com)