Pratica Chef Express Service Manual page 67

High Voltage Capacitor
The capacitor utilized in the microwave circuit stores energy during half of the power cycle. It releases
it during the other half of the cycle and aids the transformer to produce the 4.000V of continuous
current to the Magnetron.
The capacitor has an internal drainage resistor (10MΩ) to assist with discharging when power is cut
off. The necessary time for the complete discharge is of approximately 5 minutes but can be manually
discharged by grounding each terminal to the oven chassis.
Testing High Voltage Capacitor
WARNING: Never attempt to measure high voltage directly. Death or serious injury could
result. Always make sure to discharge the capacitor manually before commencing repair.
To perform the capacitor test, a multimeter will be necessary.
1) Unplug the oven and wait 5 minutes for the high voltage capacitor to discharge or discharge
manually by grounding each capacitor terminal.
2) Remove the rear panel of the unit.
3) Unplug all wires and manually discharge capacitor.
4) With the multimeter adjusted to the highest resistance scale, measure the ohms between the
two terminals of the capacitor. The multimeter should start at zero and then go to high reading
or infinite. The same reading should apply by inverting the multimeter leads.
• If the resistance stays low, replace the capacitor.
• Check each terminal to ground, if continuity is present, replace the capacitor.
5) An alternate test can be done by checking the microfarads between the terminals of the
capacitor. The microfarads should read at 1uF +/-3%; if the reading is off, replace the
capacitor.
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