Measurement Of Microwave Power Output; Disassembly And Adjustment - LG MH9245XAB Service Manual

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MEASUREMENT OF MICROWAVE POWER OUTPUT

• 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
bowl having a maximum material thickness of 3 mm
and an outside diameter of approximately 190 mm.
• The oven and the empty bowl 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 bowl. After addition of the water to the bowl, the
load is immediately placed on the center of the
turntable which is in the lowest position and the
microwave power switched on.
• The heating time with full power for heating water can
be calculated from the following equation.
4187 x 10
T = (
) + 3 (Magnetron heat-up time)
Rating Output
In this calculation, the decimal seconds less than
1-second are rounded up.

DISASSEMBLY AND ADJUSTMENT

A. OUTER CASE REMOVAL
1) Disconnect the power supply cord from the outlet.
2) Remove the screws from the rear of the case.
The outer case must be moved backward to be lifted
off.
B. POWER SUPPLY CORD
1) Remove the outer case.
2) Disconnect two terminals and remove one screw of
the ground terminal.
C. CONTROL PANEL ASSEMBLY
1) Open the door.
2) Disconnect the leadwire from RELAY (RY2) of the
PCB SUB ASSEMBLY.
2) Disconnect the leadwire from connector (CN1) of the
PCB SUB ASSEMBLY.
3) Lift up and pull out control panel assembly carefully
from the cavity.
CAUTION: DISCHARGE THE HIGH VOLTAGE
CAPACITOR BEFORE SERVICING
(refer to page 2-1)
• The microwave power output P in watts is calculated
from the following formula:
4187 x (T
P =
• T
: Temperature of water after heating
2
• T
: Temperature of bowl before heating
0
• M : Weight of bowl
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 bowl, 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
WATER LOAD
WATER LOAD
Remove the screw
Lift up and pull out control panel
5-3
– T
) + 0.55 X (T
- T
)X M
2
1
2
0
T
BOWL
BOWL
BOWL
TURNTABLE
TURNTABLE
TURNTABLE

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