Rebuilding the -100 V section of the power supply
Steps
- Q3: MJE15031 (System 11/11A used SDS202, so cross the legs). MJE350 or 2N5416 with a heat sink also work.
- Q4: 2N5551 (or MPSD02, NTE287).
- ZR3: 1N4730A (3.9 V 1 W). ZR4: 1N4763A (91 V 1 W) in place of the 1N4764A.
- D4: 1N4004. R4: 39k 1 or 2 W flame-proof. R5: 680 ohm 1/2 W. R6: 330k 1/2 W. C4: 0.1 uF 250 V metal polyester.
- Replace everything in the section at once rather than only the parts that test bad.
The display supply runs at about 100 V DC (plus and minus) with large filter capacitors; work with the game off and unplugged, and measure live only with insulated probes.
Systems
Related tips
- Display supply low (under 90 V) after the resistors are changed
- Game boots only sometimes, 5 V drops out: cracked diode D6 on the power supply
- Lower the display voltage to 91 V to extend display life
- Displays show only three or four digits at a time in a slow wipe
- Rebuild the high-voltage section of a 520-5047-00/-01/-02 supply
- Rebuild the solenoid driver board high-voltage section
- Check every coil's resistance before first power-up
- Check every coil's resistance before first power-up
Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell