LG MD-2642KT, Service Manual

Page: 13 / 43

5-3
• Microwave power output measurement is made with the
microwave oven supplied at its rated voltage and operated at its
maximum microwave power setting with a load of (1000±5) g of
potable water.
• The water is contained in a cylindrical borosilicate glass vessel
having a maximum material thickness of 3 mm and an outside
diameter of approximately 190mm.
• The oven and the empty vessel are at ambient temperature prior
to the start of the test.
• The initial temperature (T1) of the water is (10±2)°C It is
measured immediately before the water is added to the vessel.
After addition of the water to the vessel, the load is immediately
placed on the center of the turntable which is in the lowest
position and the microwave power switched on.
• The time T for the temperature of the water to rise by a value
∆
T
of (10±2)° is measured, where T is the time in seconds and
∆
T
is the temperature rise. The initial and final water temperatures
are selected so that the maximum difference between the final
water temperature and the ambient temperature is 5°.
• The microwave power output P in watts is calculated from
the following formula :
4187 x (
∆
T)
T
is measured while the microwave generator is operating at
full power. Magnetron filament heat-up time is not included.
(about 3 sec)
• The water is stirred to equalize temperature throughout the
vessel, prior to measuring the final water temperature.
• Stirring devices and measuring instruments are selected in
order to minimize addition or removal of heat.
WATER LOAD
TURNTABLE
MEASUREMENT OF MICROWAVE POWER OUTPUT
P =
MEASUREMENT WITH OUTER CASE
REMOVED
• When you replace the magnetron, measure for microwave
energy leakage before the outer case is installed and after
all necessary components are replaced or adjusted.
Special care should be taken in measuring the following
parts. (Circled area of Fig. below)
- Around the magnetron
- The waveguide
MEASUREMENT WITH A FULLY
ASSEMBLED OVEN
• After all components, including the outer case, are fully
assembled, measure for microwave energy leakage around
the door viewing window, the exhaust opening, and air inlet
openings.
• Microwave energy leakage must not exceed the values
prescribed below.
NOTE: Leakage with the outer case removed less than 5
mW/cm.sq. Leakage for a fully assembled oven
(Before the latch switch (primary) is interrupted) with
the door in a slightly opened position-less than 2
mW/cm
2 .sq.
NOTES WHEN MEASURING
• Do not exceed meter full scale deflection.
• The test probe must be removed no faster than
1 inch/sec (2.5 cm/sec) along the shaded area, otherwise a
false reading may result.
• The test probe must be held with the grip portion of the
handle. A false reading may result if the operator's hand is
between the handle and the probe.
• When testing near a corner of the door, keep the probe
perpendicular to the surface making sure the probe
horizontally along the oven surface; this may cause probe
damage.
RECORD KEEPING AND NOTIFICATION
AFTER MEASUREMENT
• After adjustment and repair of any microwave energy
interruption or microwave energy blocking device, record
the measured values for future reference. Also enter the
information on the service invoice.
• The microwave energy leakage should not be more than 4
mW/cm.sq. after determining that all parts are in good
condition, functioning properly and genuine replacement
parts which are listed in this manual have been used.
• At least once a year, have the electromagnetic energy
leakage monitor checked for calibration by its manufacturer.
WARNING : AVOID CONTACTING ANY
HIGH VOLTAGE PARTS