Measurement Of Microwave Power Output; Disassembly And Adjustment - LG MB-3949G Service Manual

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
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 thd lowest position and the
microwave power switched on.
• The time T for the temperature of the water to rise by a
∆ T of (10±2)°K is measured, where T is the time
value
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°K.

DISASSEMBLY AND ADJUSTMENT

A. OUTER CASE REMOVAL
1) Disconnect the power supply cord from the outlet.
2) Remove the screws from the rear and along side
edges 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 earth terminal.
CAUTION: DISCHARGE THE HIGH VOLTAGE
CAPACITOR BEFORE SERVICING
(refer to page 2-1)
LGE Internal Use Only
• The microwave power output P in watts is calculated
from the following formula :
4187 x (∆T) + 0.55 X (T
P =
• T : Temperature after heating
2
• T : Temperature of bowl
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 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
C. CONTROL PANEL ASSEMBLY
1) Disconnect the leadwire from the Timer motor.
2) Remove the screws for securing the control panel.
3) Lift control panel ASS'Y from the oven by the tab
unhooked.
5-3 Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
- T ) X M
2 0
T
TURNTABLE