A special solenoid (pop bumper or slingshot) fires in the solenoid test but not during play, or fires in play but not in the test.
Pop or sling works in the game but not in test, or the reverse
Cause: The two triggers meet at a 7408 gate (IC6/IC7) before a shared 7402 (IC8/IC9), pre-driver and driver. Works in play only: the 7408 or the PIA that drives it in test. Works in test only: the 4.7k pull-up resistor (R1-R6), the 7408, the playfield switch, its capacitor and resistor, or its connector.
Checks
- If it works either way, the 7402, transistors and coil are fine.
- Check R1-R6 with a meter; they drift or go open.
- Diode-test or logic-probe the 7408.
Fix
- Replace the failed resistor, gate or switch parts. A fault that only affects the test does not affect play.
Systems
Related tips
- Pop bumper or slingshot locked on
- CPU-controlled and special solenoids
- Special solenoid trigger test at 2J12/2J13
- Solenoid driver test at 2J9 and 2J11 with Leon's code
- 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
- Check the wire from the coil to its driver transistor
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)