Solenoid driver test at 2J9 and 2J11 with Leon's code

Steps

• Tester LED plain lead to +5 V; no other hookup is needed.
• Touch each pin of 2J9 and 2J11; each should blink.
• If one is missing while IC5 is good, check the 7408 gates on IC1-IC4 (pins 1-2, 4-5, 9-10 and 12-13).
• If the 7408 is good, the 2N4401 pre-driver (Q14-Q44, even) or TIP120/TIP102 driver (Q15-Q45, odd) has failed.

Systems

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

Related tips

• One or a few coils lock on at power-up
• Diode-test the TIP120/TIP102 and 2N4401
• CPU and driver board transistors by position
• Quick test for shorted TIP122/TIP102 drivers
• Quick check of all TIP122/102 drivers before first power-on
• Flash lamp stuck on and melting plastics on L/R reversed games
• A coil or flasher comes on and stays on at power-up
• Test a TIP120/TIP102 solenoid driver with a meter

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