Test Procedures - Frigidaire CFMV152KW Servicing Manual

Test Procedures

Procedure
Letter
A MAGNETRON ASSEMBLY TEST
High voltages are present during the cook cycle, so extreme caution should be
observed. Discharge the high voltage capacitor before touching any oven components
or wiring.
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
4. To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity
check across the magnetron filament leads should indicate less than 1 ohm.
5. To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament
leads and chassis ground. This test should indicate an infinite resistance. If there is little or no
resistance the magnetron is grounded and must be replaced.
6. Reconnect all leads removed from components during testing.
7. Reinstall the outer case (cabinet).
8. Reconnect the power supply cord after the outer case is installed.
9. Run the oven and check all functions.
MICROWAVE OUTPUT POWER
Power output of the magnetron can be measured by performing a water temperature rise test. This
test should only be used if above tests do not indicate a faulty magnetron and there is no defect in
the following components or wiring: silicon rectifier, high voltage capacitor and power transformer.
This test will require a 16 ounce (453 cc.) measuring cup and an accurate mercury thermometer or
thermocouple type temperature tester. For accurate results, the following procedure must be
followed carefully:
1. Fill the measuring cup with 16 oz. (453 cc.) of tap water and measure the temperature of
the water with a thermometer or thermocouple temperature tester. Stir the thermometer or
thermocouple through the water until the temperature stabilizes. Record the temperature of the
water.
2. Place the cup of water in the oven. Operate oven at 100% POWER selecting more than 60
seconds cook time. Allow the water to heat for 60 seconds, measuring with a stop watch,
second hand of a watch or the digital read-out countdown.
3. Remove the cup from the oven and again measure the temperature, making sure to stir the
thermometer or thermocouple through the water until the maximum temperature is recorded.
4. Subtract the cold water temperature from the hot water temperature. The normal result should
be 29.2 to 54.2°F (16.2 to 30.1°C) rise in temperature. If the water temperatures are accurately
measured and tested for the required time period the test results will indicate if the magnetron
tube has low power output (low rise in water temperature) which would extend cooking time or
high power output (high rise in water temperature) which would reduce cooking time. Because
cooking time can be adjusted to compensate for power output, the magnetron tube assembly
should be replaced only if the water temperature rise test indicates a power output well beyond
the normal limits. The test is only accurate if the power supply line voltage is 120 volts and the
oven cavity is clean.
WARNING
Section 3 Troubleshooting and Testing
Component Test
3-3