Fitting the high-voltage kit
The MJE15030/15031 need their legs crossed to replace SDS201/202, except on later System 11B and 11C boards. The 91 V zeners drop the display supply by about 9 V for longer display and driver life. Stand the 2 W resistors a little off the board to help cooling.
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
- Williams System 3
- Williams System 4
- Williams System 6 / 6A
- Williams System 7
- Williams System 9
- Williams System 11
- Williams System 11A
- Williams System 11B
- Williams System 11C
Related tips
- Routine high-voltage changes on every System 11 power supply
- High-voltage supply rebuild parts, System 3 to 11C
- Display voltages at 3J5, power supply D-8345 (High Speed to Swords of Fury)
- Display voltages at 3J2, power supply D-11883/D-12246 (Taxi to Dr. Dude)
- Game boots only sometimes, 5 V drops out: cracked diode D6 on the power supply
- System 11 backbox boards and supplies
- What the System 11 power supply board feeds
- System 11 power supply versions D-8345 and D-12246
Source: Williams Systems 3 - 11c High Voltage Parts Kit