Cross the legs when MJE15030/15031 replace SDS201/SDS202

The SDS201 and SDS202 are no longer made. MJE15030 and MJE15031 replace them only with the legs crossed so emitter, base and collector meet the right pads. Do this only on supplies that originally had SDS parts; later System 11B and 11C boards take the MJE parts straight in.

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

• Rebuild the high-voltage section of a 520-5047-00/-01/-02 supply
• Rebuilding the +100 V section of the power supply
• -125 V and -113 V read the same and the display is dark
• 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
• +5 V fuse blows the instant the game is switched on

Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell