Spare transistors for driver board and power supply
Coil drivers take TIP102 (replacing TIP120) with 2N4401 pre-drivers. Lamp matrix columns use TIP42, rows use 2N6122 (or TIP41/NTE196), and 2N6427 (or MPSA14) serve as row and column pre-drivers; the lamp matrix also uses 2N5060 SCRs. The high-voltage display supply uses MJE15030, MJE15031, MPSD52 and MPSD02 transistors.
Systems
Related tips
- Driver board transistors and what they drive
- A low resistance coil points to a bad driver transistor
- Coil locks on and new transistors don't help: a failed 7408 on the driver board
- System 6 and System 7 driver boards can be swapped for testing
- Hyperball driver board is unique
- Coil has power and wiring is good but still dead or locked on
- Test a 2N4401 pre-driver with a meter
- Leon's code with the driver board attached
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part One, Clay Harrell (pinrepair.com)