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Servicing the Inverter Unit
WARNING
THIS INVERTER UNIT CONTAINS CIRCUITRY CAPABLE OF PRODUCING HIGH VOLTAGE AND HIGH
CURRENT. CONTACT WITH ANY PART OF THE HIGH VOLTAGE WILL RESULT IN ELECTROCUTION.
DO NOT ACCESS ANY PARTS OF INVERTER UNIT WITH POWER SUPPLY CONNECTED.
DO NOT OPERATE INVERTER UNIT ITSELF.
IT IS DANGEROUS BECAUSE THIS UNIT CONTAINS HIGH VOLTAGE COMPONENTS.
Microwave Measurement Procedure
A. Requirements:
1) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a
microwave oven should not exceed 1 mW/cm2 at any point 5cm or more from the external surface of
the oven, measured prior to acquisition by a purchaser, and thereafter (through the useful life of the
oven), 5 mW/cm2 at any point 5cm or more from the external surface of the oven.
2) Safety interlock switches: Primary interlock switch shall prevent microwave radiation emission in
excess of the requirement as above mentioned, secondary interlock switch shall prevent microwave
radiation emission in excess of 5 mW/cm2 at any point 5cm or more from the external surface of the
oven.
B. Preparation for testing:
Before beginning the actual measurement of leakage, proceed as follows:
1) Make sure that the actual instrument is operating normally as specified in its instruction booklet.
Important:
Survey instruments that comply with the requirement for instrumentation as prescribed by the
performance standard for microwave ovens, 21 CFR 1030.10(c)(3)(i), must be used for testing.
2) Place the oven tray in the oven cavity.
3) Place the load of 275±15 ml (9.8 oz) of tap water initially at 20o±5C (68oF) in the center of the oven
cavity. The water container shall be a low form of 600 ml (20 oz) beaker with an inside diameter of
approx. 8.5 cm (3-1/2 in.) and made of an electrically nonconductive material such as glass or plastic.
The placing of this standard load in the oven is important not only to protect the oven, but also to
insure that any leakage is measured accurately.
4) Set the cooking control on Full Power Cooking Mode
5) Close the door and select a cook cycle of several minutes. If the water begins to boil before the
survey is completed, replace it with 275 ml of cool water.
C. Leakage test:
Closed-door leakage test (microwave measurement)
1) Grasp the probe of the survey instrument and hold it perpendicular to the gap between the door and
the body of the oven.
2) Move the probe slowly, not faster than 1 in./sec. (2.5 cm/sec.) along the gap, watching for the
maximum indication on the meter.
3) Check for leakage at the door screen, sheet metal seams and other accessible positions where the
continuity of the metal has been breached (eg., around the switches, indicator, and vents).
While testing for leakage around the door pull the door away from the front of the oven as far as is
permitted by the closed latch assembly.
4) Measure carefully at the point of highest leakage and make sure that the highest leakage is no greater
than 4mW/cm2, and that the primary interlock switch and secondary interlock switch do turn the oven
OFF before any door movement.
NOTE: After servicing, record data on service invoice and microwave leakage report.
Basic Information
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