Replace burnt 3 watt lamp resistors with 5 watt
The original 3 watt carbon feature-lamp resistors on the driver board almost always burn. Replace them with 27 ohm 5 watt sand (wirewound) resistors; there are eight per driver board.
Systems
Related tips
- Burnt 27 ohm lamp matrix resistors R149-R156 on the driver board
- Fixing the burnt lamp matrix resistors R149-R156
- Test a TIP42 lamp column transistor with a meter
- Test a 2N5060 lamp matrix SCR with a meter
- Replace the TIP42 lamp column transistors with IRF9Z34N MOSFETs
- Test a 2N6122/TIP41 lamp row transistor with a meter
- Test a 2N6427 (MPSA14) lamp matrix transistor with a meter
- All coils or lamps lock on at power-up
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part One, Clay Harrell (pinrepair.com)