Rebuilding the +100 V section of the power supply
Steps
- Rebuild when the high-voltage fuse blows and the display board and glass are cleared. Fit every part in a kit if you use one.
- Q1: MJE15030 (System 11B on is factory MJE15030; System 11/11A used SDS201, so cross the legs). MJE340 or 2N3440 with a heat sink also work.
- Q2: 2N5401 (or MPSD52, NTE288).
- ZR1: 1N4730A (3.9 V 1 W). ZR2: 1N4763A (91 V 1 W) in place of the 1N4764A.
- D3: 1N4004. R1: 39k 1 or 2 W flame-proof. R2: 680 ohm 1/2 W. R3: 330k 1/2 W. C2: 0.1 uF 250 V metal polyester.
- Cut the old parts out, clear the holes with a solder sucker, solder both sides where possible and stand resistors slightly off the board.
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
- Cross the legs when MJE15030/15031 replace SDS201/SDS202
- 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
Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell