Quick check of all TIP122/102 drivers before first power-on
Steps
- With the game off, set the meter to continuity.
- Hold one probe on the backbox ground strap.
- With the second probe, touch the metal tab of each TIP122/102: the 16 at the lower left of the CPU board, the six at the upper right and the eight in a vertical row at the lower right.
- A beep (zero ohms) means that transistor is shorted.
- Replace a shorted TIP122 with a TIP102 before powering up, and replace its 2N4401 pre-driver too.
Systems
Related tips
- CPU and driver board transistors by position
- Quick test for shorted TIP122/TIP102 drivers
- Solenoid driver test at 2J9 and 2J11 with Leon's code
- One or a few coils lock on at power-up
- A coil or flasher comes on and stays on at power-up
- Flash lamp stuck on and melting plastics on L/R reversed games
- Diode-test the TIP120/TIP102 and 2N4401
- Use TIP102 when replacing a TIP122
Source: Repairing Williams System 11 Pinball 1986 to 1990, Deel 1, Clay Harrell (pinrepair.com)