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TROUBLESHOOTING & REPAIR
INPUT POWER FACTOR CAPACITOR VOLTAGE CHECK
AND DISCHARGE PROCEDURE (continued)
FIGURE F.1 – POWER FACTOR CAPACITOR DISCHARGE DETAILS
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TEST PROCEDURE
1.Remove input power to the machine.
2.With the 5/16" nut driver, remove the sheet metal screws that hold the right case side in place. Remove the right case side.
3.With the volt/ohmmeter, carefully check the voltage across the input power factor capacitors. When input power is removed, the voltage across each capacitor should be zero. (Normally, the capacitors dis- charge through the primary winding in the main transformer.)
4.If capacitor voltage is zero, you may begin working on the Square Wave TIG 355.
5.If any voltage is present, DISCHARGE EACH INDIVIDUAL CAPACITOR as follows:
a. Grip the 500 ohm resistor with insu- lated gloves and insulated gripping pli- ers.
b.Hold the resistor across the terminals on each capacitor for 20 seconds. See Figure F.1.
c.With the volt/ohmmeter, recheck each capacitor for voltage.
6.After all the capacitors are discharged completely, check for broken capacitor leads or an open primary winding on the main transformer, which would have pre- vented the capacitors from discharging normally.
SQUARE WAVE TIG 355
