Way back, when Clay had his excellent repair guides on-line, he recommended the following upgrades to the High Voltage section of all Williams System-3 through System-7 Power Supplies:

  1. Replace Z1 and Z3 1N5990 Zener diodes (3.9V 1/2W) with 1N4730 (3.9V 1W)
  2. Replace Z2 and Z4 1N4764 Zener diodes (100V) with 1N4763 (90V)
  3. Replace R2 and R5 680 Ohm 1/2 Watt resistors with 1.2K Ohm 1/2 Watt
  4. Replace R1 and R4 39K Ohm 1/2 Watt with 39K Ohm 2 Watt.

These upgrades will increase the reliability of the HV section, and will drop the display high voltage from 100 volts to 90 volts, which will work fine and may increase the lifespan of your displays.

Created 12/4/11 - Last Modified 12/4/11 - Steve Kulpa Mail Icon   Nolensville, TN
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