Measure a rebuilt supply before reconnecting the displays

After a rebuild, measure the outputs with 3J5 (or 3J2) still unplugged. Plug the displays back in only when both rails read 90 to 105 V.

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 11
• Williams System 11A
• Williams System 11B
• Williams System 11C

Related tips

• Fix the display short before trusting a rebuilt supply
• Display voltages at 3J2, power supply D-11883/D-12246 (Taxi to Dr. Dude)
• Display voltages at 3J5, power supply D-8345 (High Speed to Swords of Fury)
• What the System 11 power supply board feeds
• Low +5 V (below 4.9 V) from the power supply
• Low +12 V (below 10.5 V)
• Display supply low (under 90 V) after the resistors are changed
• Rebuilding the +100 V section of the power supply

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