LG LMC1575BD User manual

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CAUTION
BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
LMC1575BD
LMC1575ST
LMC1575SW
LMC1575SB
P/NO.: MFL69902602
MODEL:
MICROWAVE OVEN
SERVICE MANUAL
February, 2017
Printed in Korea
Copyright © 2017 LG Electronics Inc. All rights reserved. Only training and service purposes

This device is to be serviced only by properly qualified service personnel.
Consult the service manual for proper service procedures to assure continued safety operation and for precautions to be taken to avoid possible exposure to
excessive microwave energy.
PRECAUTIONS TO BE OBSERVED BEFORE AND
DURING SERVICING TO AVOID POSSIBLE EXPOSURE
TO EXCESSIVE MICROWAVE ENERGY
A) Do not operate or allow the oven to be operated with the door open.
B) Make the following safety checks on all ovens to be serviced before activating the magnetron or other microwave source, and make repairs as
necessary; (1) interlock operation, (2) proper door closing, (3) seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or
loosening of hinges and latches, (5) evidence of dropping or abuse.
C) Before turning on microwave power for any service test or inspection within the microwave generating compartments, check the magnetron,
wave guide or transmission line, and cavity for proper alignment, integrity, and connections.
D) Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation and transmission systems shall be
repaired, replaced, or adjusted by procedures described in this manual before the oven is released to the owner.
E) A microwave leakage check to verify compliance with the Federal Performance Standard should be performed on each oven prior to release to
the owner.
CAUTION
MICROWAVE RADIATION
DO NOT BECOME EXPOSED TO RADIATION FROM THE MICROWAVE GENERATOR OR OTHER PARTS
CONDUCTING MICROWAVE ENERGY.
SAFETY PRECAUTIONS

(Page)
SAFETY PRECAUTIONS ------------------------------------------------------------------------------------------------------------------------------------------ Inside front cover
SPECIFICATIONS
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 1-1
CAUTIONS
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 2-1
INSTALLATION
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ 3-1
OPERATING INSTRUCTIONS
--------------------------------------------------------------------------------------------------------------------------------------------------------- 4-1
FEATURES ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ 4-1
CONTROL PANEL -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 4-1
OPERATING SEQUENCE --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 4-2
SCHEMATIC DIAGRAM ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ 4-4
CIRCUIT DESCRIPTION ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 4-5
SERVICE INFORMATION ---------------------------------------------------------------------------------------------------------------------------------------------------------------- 5-1
TOOLS AND MEASURING INSTRUMENTS ------------------------------------------------------------------------------------------------------------------------------------------------------- 5-1
MICROWAVE LEAKAGE TEST -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 5-1
MEASUREMENT OF MICROWAVE POWER OUTPUT --------------------------------------------------------------------------------------------------------------------------------------- 5-3
DISASSEMBLY AND ADJUSTMENT ------------------------------------------------------------------------------------------------------------------------------------------------------------------ 5-4
INTERLOCK CONTINUITY TEST ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- 5-9
COMPONENT TEST PROCEDURE ----------------------------------------------------------------------------------------------------------------------------------------------------------------- 5-10
TROUBLE SHOOTING ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 5-12
Trouble shooting for inverter PCB --------------------------------------------------------------------------------------------------------------------------------------------------------------------- 5-18
EXPLODED VIEW -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 6-1
CONTENTS

1-1
ITEM DESCRIPTION
Power Requirement Power Input Voltage 120 V~ 60 Hz Single phase, 3 wire grounded
Power Consumption 1250 watt
Initial Power Requirement 1920 watt
Power Output 1200 watt Max. microwave power (IEC60705)
Microwave Frequency 2450 MHz
Magnetron 2M286.A21TBG
Timer Digital, Up to 99min 59sec.
Outside Dimensions(W x H x D) 21 7/16" x 12 1/8" x 17"(54.4 cm x 30.8 cm x 43.2 cm)
Cavity Dimensions(W x H x D) 15 9/16" x 10 5/16" x 16"(39.5 cm x 26.2 cm x 40.6 cm)
Net Weight 27.5 lbs (approx.)
12.5 kg (approx.)
Shipping weight 32 lbs (approx.)
14.5 kg (approx.)
Control Complement Touch Control System Microwave Power for Variable Cooking Power level
100% / 90% / 80% / 70% / 60% / 50% / 40% / 30% / 20% / 10%
Rating Label
Location
Accessories Manual / Shaft / Glass turntable / Rotating Ring
This microwave oven is designed for household use only.
It is not recommended for commercial purposes.
SPECIFICATIONS

2-1
Unlike other appliances, the microwave oven is high-voltage and
high-current equipment.
Though it is free from danger in ordinary use, extreme care should be
taken during repair.
• DO NOT operate on a 2-wire extension cord during repair and use.
• NEVER TOUCH any oven components or wiring during operation.
• BEFORE TOUCHING any parts of the oven, always remove the power plug from
the outlet.
• For about 30 seconds after the oven stops, an electric charge remains in the
inverter PCB. When replacing or checking, you must wait 30 seconds more after
the oven stop.
• Remove your watches whenever working close to or replacing the Magnetron.
• DO NOT touch any parts of the control panel circuit. A resulting static electric
discharge may damage this P.C.B.
• NEVER operate the oven with no load.
• NEVER injure the door seal and front plate of the oven cavity.
• NEVER put iron tools on the magnetron.
• NEVER put anything into the latch hole and the interlock switches area.
MICROWAVE RADIATION
Personnel should not be exposed to the microwave energy which may
radiate from the magnetron or other microwave generating device if it is
improperly used or connection.
All input and output microwave connections, waveguide, flange, and
gasket must be secure never operate the device without a microwave
energy absorbing load attached.
Never look into an open waveguide or antenna while the device is
energized.
• Proper operation of the microwave oven requires that the magnetron be
assembled to the waveguide and cavity. Never operate the magnetron unless it
is properly installed.
• Be sure that the magnetron gasket is properly installed around antenna.
whenever installing the magnetron.
THE OVEN IS TO BE SERVICED ONLY BY PROPERLY
QUALIFIED SERVICE PERSONNEL.
CAUTIONS
Gasket
ANTENNA
COOLING FIN
MAGNETRON
CHASSIS GROUND
FILAMENT
TERMINALS
MAGNETRON

2-2
CAUTIONS
DANGER OF HIGH VOLTAGE AND HIGH TEMPERATURE OF THE INVERTER POWER SUPPLY
WARNING
This inverter board looks like a regular PCB. However, This PCB drive the magnetron with extremely high voltage and high current. Take
cautionary measure when disassembling and troubleshooting the inverter PCB. Improper handling can result in electric shock or burns ,
which might lead to injury or death.
1. Inverter power supply has very high voltage and high current circuit.
It functions the same as the high voltage transformer and high voltage capacitor in ordinary microwave oven.
2. Very high voltage may remain in circuitry even when oven is off. High voltage charge may remain in the capacitors on the board.
After oven off, wait 60 seconds to discharge the high voltage capacitors of inverter unit.
3. Do not touch circuitry because it has very hot (high voltage) circuitry. Even when replacing board, extreme care should be taken to avoid
possible electric shock hazards. High voltage charge may remain in circuits
4. Do not touch aluminum heat sink because it is energized very high voltage and it is very hot in high heat energy.
5. Do not test oven while inverter grounding screw is loose. It is very dangerous to operate H.V inverter circuit with loose grounding screw
or if improperly grounded.
Bridge
Diode
Heat sink
IGBT
Resonant
capacitor
Earth wire
MGT(Output)
High Voltage Capacitor
High Voltage
Diode
DC capacitor
Choke coil
Current
Transformer
L - N(Input)
Communication
Connector
Sub PCB
Bridge diode
Heat sink Shunt resistor
IGBT
Resonant capacitor
Earth wire
MGT(Output)
H.V Capacitor
H.V Transformer High
Voltage
Diode
DC capacitor
Downloader
Connector
Choke coil
Comm.
Connector
L - N(Input)
H.V Transformer
LMC1575BD /01
LMC1575ST /01
LMC1575SW /01
LMC1575SB /01
LMC1575BD /00
LMC1575ST /00
LMC1575SW /00
LMC1575SB /00

3-1
BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY.
INSTALLING
1. Empty the microwave oven and clean inside it with a soft, damp cloth. Check for
damage such as misaligned door, damage around the door or dents inside the
cavity or on the exterior.
2. Put the oven on a counter, table, or shelf that is strong enough to hold the oven
and the food and utensils you put in it.
3. Do not block the vent and the air intake openings.
Blocking vent or air intake openings can cause damage to the oven and poor
cooking results. Make sure the microwave oven legs are in place to ensure
proper air flow.
4. The oven should not be installed in any area where heat and steam are
generated, because they may damage the electronic or mechanical parts of the
unit.
Do not install the oven next to a conventional surface unit or above a conventional
wall oven.
5. Use microwave oven in an ambient temperature less than 104°F(40°C).
6. Place the microwave oven on a sturdy and flat surface at least 10 cm(4 inches)
from the wall.
7. Place the microwave oven as far away as possible from TV, Radio, Computer,
Bluetooth equipment or Wi-Fi devices, etc., to prevent interference.
10cm
PREFERRED METHOD
ENSURE PROPER GROUND
EXISTS BEFORE USE
TEMPORARY METHOD
(ADAPTER PLUGS NOT
PERMITTED IN CANADA)
ALIGN LARGE
PRONGS/SLOTS
ENSURE PROPER GROUND
AND FIRM CONNECTION
BEFORE USE
GROUNDING INSTRUCTIONS
For personal safety,this appliance must be fully grounded at all times.
In the event of an electrical short circuit, grounding reduces the risk of electrical
shock.
The plug must be plugged into an outlet that is properly installed and grounded.
WARNING
Improper use of the grounding plug can result in a risk of electric shock.
Do not, under any circumstances, cut or remove the third ground prong
from the power cord plug.
10cm
PREFERRED METHOD
ENSURE PROPER GROUND
EXISTS BEFORE USE
TEMPORARY METHOD
(ADAPTER PLUGS NOT
PERMITTED IN CANADA)
ALIGN LARGE
PRONGS/SLOTS
ENSURE PROPER GROUND
AND FIRM CONNECTION
BEFORE USE
INSTALLATION

4-1
FEATURES
OPERATING INSTRUCTIONS

4-2
CONTROL PANEL
1
4
12
11
10
2
3
6
5
9
8
10
12
11
7
1. SMART DIAGNOSIS: Hold the mouthpiece of a phone up to this
icon when directed to by service center personnel, to help
diagnose problems with the oven when calling for service.
2. DISPLAY: The Display includes a clock and indicators to tell you
time of day, cooking time settings, and cooking functions selected.
3. SENSOR COOK: Touch this key to cook bacon, fresh vegetables,
frozen entrees, frozen vegetables, oatmeal, potatoes, and rice.
4. SENSOR REHEAT: Touch this key to reheat beverages,
casseroles, dinner plates, pie, and pizza.
5. SENSOR POPCORN: Touch this key to pop popcorn.
6. DEFROST: Touch this key to select food type and defrost food by
weight.
7. POWER LEVEL: The microwave oven is equipped with 10 power
levels for maximum flexibility and control over cooking. The
Microwave Power Levels section contains suggestions for which
power level to use when preparing various foods.
8. COOK TIME: Touch this key to manually set a desired cook time.
9. TIMER ON/OFF: Touch this key to set a kitchen timer.
10. MORE / LESS: Set cooking time and weight. Lengthen or
shorten the cooking time at any point by pressing the key.
(Not available in Defrost mode.)
11. STOP / CLEAR: Touch this key to stop the oven or to clear all
entries except time of day.
12. START / ENTER: Touch this key to start a function, accept
selections, or resume cooking if the door was opened or the
STOP button was pressed once.
Pressing START without setting a cook time activates the Quick
Start feature. Each press of the START button adds 30 seconds
to the cooking time.

4-3
The following is a description of component functions during oven operation.
1. Inverter power supply circuit.
The inverter power supply circuit powered from the line voltage, 120 V~ 60 Hz
AC input supplies 4000 V DC to the magnetron. and functions in placed of the
H.V transformer, the H.V capacitor , and H.V diode.
1. The AC input voltage 120 V~ 60 Hz is rectified to DC voltage immediately.
2. DC voltage will be supplied to the switching devices called IGBT. These
devices are switched ON-OFF by the 24 to 70 kHz PWM (pulse width
modulation) signal from the microcomputer in the DPC.
3. This drives the High voltage transformer to increase voltage up to 2000 V AC.
4. Then the half-wave doubler voltage rectifier circuit, consisting of the H.V.
diodes and capacitors, generates the necessary 4000 V DC needed for the
magnetron.
5. Consumption power is always monitored by the signal output from the current
transformer built into the inverter circuit.
6. This signal is fed back to the microcomputer in the DPC to determine
operating conditions and output necessary to control PWM signal to the
Inverter Power Supply for control of the output power.
2. Power output reduction.(Normal condition)
1. In 100%, 90% and 80% power levels, output power will gradually be reduced
to avoid overheating.
1-1. for example of 100% power,
After about 1 minute, the output power will be reduced to 90%.
1-2. and then the output power will be reduced from 90% to 70% for
6minutes gradually.
1-3. and then 70% will be kept on.
2. If the power level starts at 90%, the level will be kept till 1minute and then
reduced to 70% gradually.
3. Power output reduction.
(Continues using condition)
Continues using make inverter overheating. To protect inverter PCB from
overheating, Inverter detect temperature itself.
1. If you restart product within 15 minutes from the end of working, the power
consumption is the same power consumption of the end of working.
2.
If you unplug the power cord and then you plug the power cord, the power
consumption is max power.
4. Variable power cooking control
High Voltage Inverter Power Supply controls output power by the signal from
Digital Programmer Circuit. Power relay always stay on, but PWM (Pulse Width
Modulation) signal controls microwave output power
Power Level Use
High
(100 %)
* Boiling water.
* Browning ground beef.
* Making candy.
* Cooking poultry pieces, sh, & vegetables.
* Cooking tender cuts of meat.
90 *Reheating rice, pasta, & vegetables.
80 * Reheating prepared foods quickly.
* Reheating sandwiches.
70 * Cooking egg, milk and cheese dishes.
* Melting chocolate.
60 * Cooking veal.
* Cooking whole sh.
* Cooking puddings and custard.
50 * Cooking ham, whole poultry and lamb.
* Cooking rib roast and sirloin tip.
40 * Thawing meat, poultry and seafood.
30 * Cooking less tender cuts of meat.
* Cooking pork chops and roast.
20 * Taking chill out of fruit.
* Softening butter.
10 * Keeping casseroles and main dishes warm.
* Softening butter and cream cheese.
OPERATING SEQUENCE

4-4
SCHEMATIC DIAGRAM

4-5
CIRCUIT DESCRIPTION
GENERAL DETAILS
• The SMPS supplies the necessary voltage to the micom controller when power
cord is plugged in.
• When the door is closed, the primary switch is ON, the secondary switch is ON,
and the monitor switch opens (contact COM and NO).
WHEN SELECTING COOKING POWER LEVEL AND TIME
• The micom controller memorizes the function you set.
• The time you set appears in the display window.
• Each indicator light turns on to indicate that the stage has been set.
WHEN TOUCHING THE START BUTTON
• The coil of the relay is energized by the micom controller.
• Power input is supplied to the Inverter PCB through the fuse to the primary
switch and relay 2 .
• Turntable rotates.
• The fan motor rotates and cools the magnetron by blowing the air (coming from
the intake on the Back-plate).
FUSE
MICOM CONTROLLER
SECONDARY
SWITCH
PRIMARY
SWITCH
MONITOR
SWITCH
L
N
RELAY 2
inverter
• The air is also directed into the oven to exhaust the vapor in the oven through
the Left side plate.
• Cooking time starts counting down.
• 3.3 volts AC is generated from the filament winding of the inverter PCB. This 3.3
volts is applied to the magnetron to heat the magnetron filament through two
noise-preventing choke coils.
• The inverter PCB generates high voltage of approximately 4,000V negative DC.
The voltage is applied to the filament of the magnetron.
WHEN THE OVEN IS SET AT POWER LEVEL
• The inverter control micro wave out-put power from 100 % to 30 % by controlling
power consumption.
20% and 10% Power are controlled by relay on/off working.
• One complete cycle of relay 32 seconds.
WHEN THE DOOR IS OPENED DURING COOKING
• Both the primary switch and relay cut off input voltage of inverter PCB.
• ON-OFF of relay is coupled electrically with opening and closing of the
secondary switch.
• When the door is opened, the secondary switch is opened and when the door is
closed, the secondary switch is closed.
• The cooking time stops counting down.
• Relay stops functioning.
• As the door is opened, if the contact of primary switch and relay 2 and/or
secondary switch fail to open, the fuse opens due to the large current surge
caused by the monitor switch activation, which in turn stops magnetron
oscillation.
FUSE PRIMARY
SWITCH
RELAY 2
MICOM CONTROLLER
SECONDARY
SWITCH
MONITOR
SWITCH
L
N
inverter
FUSE
PRIMARY
SWITCH
RELAY 2
MICOM CONTROLLER
SECONDARY
SWITCH
MONITOR
SWITCH
L
N
inverter
FUSE PRIMARY
SWITCH
RELAY 2
MICOM CONTROLLER
SECONDARY
SWITCH
MONITOR
SWITCH
L
N
inverter
FUSE
PRIMARY
SWITCH
RELAY 2
MICOM CONTROLLER
SECONDARY
SWITCH
MONITOR
SWITCH
L
N
inverter
Door open

5-1
SERVICE INFORMATION
NECESSARY TOOLS
Tools normally used for TV servicing are sufficient.
Standard tools are listed below.
• Diagonal pliers
• Long nose pliers
• Phillips screwdriver
• Flat blade screwdriver
• Wrench (size 5mm)
• Nutdriver (size 5mm)
• Adjustable wrench
• Soldering iron
• Solder
• Vinyl insulation tape
• Polishing cloth
• Hex screw diver
NECESSARY MEASURING INSTRUMENTS
• TESTER (VOLTS-DC, AC, Ohmmeter)
• Microwave survey meter
- Holaday HI-1500
HI-1501
- Narda 8100
8200
• Inch scale
• 600 cc non conductive material beaker (glass or plastic), inside diameter: approx.
8.5 cm (31/2in.)
• Cylindrical and made of borosilicate glass vessel.
max. thickness: 3 mm
outside diameter: approx. 190mm
height: approx. 90mm
• Glass thermometer: 100°C or 212°F (1 deg scale) or digital thermometer (testo
702).
CAUTIONS
• Be sure to check microwave leakage prior to servicing the oven if the oven
is operative prior to servicing.
• The service personnel should inform the manufacture importer, or
assembler of any certified oven unit found to have a microwave emission
level in excess of 5 mW/cm2and should repair any unit found to have excessive
emission levels at no cost to the owner and should ascertain the cause of the
excessive leakage. The service personnel should instruct the owner not to use
the unit until the oven has been brought into compliance.
• If the oven operates with the door open, the service personnel should:
- Tell the user not to operate the oven.
- Contact the manufacturer.
• The service personnel should check all surface and vent openings for microwave
leakage.
• Check for microwave leakage after every servicing. The power density of the
microwave radiation leakage emitted by the microwave oven should not exceed
5 mW/cm2. Always start measuring of an unknown field to assure safety for
operating personnel from radiation leakage.
MEASURING MICROWAVE ENERGY LEAKAGE
• Pour 275±15cc of 20±5°C(68±9°F) water in a beaker which is graduated to
600 cc, and place the beaker on the center of the turntable.
• Set the energy leakage monitor to 2,450 MHz and use it following the
manufacturer's recommended test procedure to assure correct result.
• When measuring the leakage, always use the 2- inch (5cm) spacer supplied
with the probe.
• Operate the oven at its maximum output.
• Measure the microwave radiation using and electromagnetic radiation
monitor by holding the probe perpendicular to the surface being measured
Move probe along shaded area
Probe scanning speed
Less than 2.5 cm/sec
(1 in/sec)
TOOLS AND MEASURING INSTRUMENTS
MICROWAVE LEAKAGE TEST

5-2
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
WARNING : AVOID CONTACTING ANY HIGH VOLTAGE PARTS
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/cm2.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/
cm2.sq.
NOTES WHEN MEASURING
• Do not exceed meter full scale deflection.
• The test probe must be moved 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 by 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 is moved horizontally along the oven surface.
Hold vertically when testing the top and bottom, and horizontally along.
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 5 mW/cm2.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.

5-3
MEASUREMENT OF MICROWAVE POWER OUTPUT
The formula to calculate energy efficient is IEC method.
• Necessary equipment
1. Thermo-hygrometer (T0)
2. Electronic scale (mc, mw)
3. Digital thermometer (T1, T2)
4.
cylindrical container of borosilicate glass (min. thickness 3 mm * external diameter
190 mm* Height 90)
5. Stopwatch (T : Total time)
6. Digital Power Meter (Energy Consumption, Wh)
7. Oscilloscope, High Voltage Probe (Magnetron Filament heating-up time)
8. Insulation Glove (to move container)
•Test method
1) The MWO & A cylindrical container are at ambient temperature for at least 6 hr.
(T0 should be 20 ± 1℃ )
2) The ambient temperature (T0) of room must be recorded by Thermo-
hygrometer.
3) The weight of empty cylindrical container #1 should be measured by Electronic
scale. . (mc, Unit: g)
4) A quantity over 1000g (Drinking water, initial temp. 8℃ ↓) is added to the
cylindrical container #2. The water temperature (T1) is measured immediately
when the water initial temperature (T1) is reached at 10 °C ± 0.2. And then, the
water (1000 ± 5 g) is poured into the cylindrical container #1 and its actual mass
obtained. (mw, Unit: g). The container is then immediately placed in the center
of the oven. Total time (T) is set.
5) Total time(T) can be obtained by repeat testing in other to raise the water
temperature, 10° C ± 0.2℃
For the measurement of the heating-up time of the magnetron filament can be
used in conjunction with an oscilloscope.
t is heating time, excluding the magnetron filament heating-up time. The MWO is
operated. Stop watch is used to count total time. And Energy consumption(Wh)
should be measured from start of operation until T2 is reached. (The MWO is
supplied at rated voltage ± 1 %)
6) The MWO is then switched off and the final water temperature(T2) is measured
within 60s. (Note: The water is stirred before its temperature is measured.)
MW power output (unit: W)
P = {4.187 x mwx (T2-T1) + 0.55 x mcx (T2-T0)} / t
Energy efficiency
η = (P x t) / (W x T) x 100
t : T(s) – MGT Filament heating-up time
W = Energy consumption(Wh) x 3600s / T
WATER LOAD
TURNTABLE
BOWL
Simple test method.
• Use this method if testing IEC method is impossible.
For exact result, use IEC method.
This method is for olny this model.
Test condition is different model by model.
1. Check max. power consumption of Micro wave mode.If it is not 1570W±80W,
Check that the inverter is problem.
2. Contain 1000CC. 10℃ water in cylindrical container.
3. Put the water in the microwave ovne and operate it for 45 seconds with max
power.
4. After operation,measure water temperature.
5. The water temperature should have a minimum temperature of 18℃.

5-4
DISASSEMBLY AND ADJUSTMENT
A. OUTER CASE REMOVAL
1) Disconnect the power supply cord from the outlet.
2) Remove the screws from the rear and both side 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 lead wire from RELAY and all connectors of the PCB SUB
ASSEMBLY.
3) Remove one screw on top and behind control panel and Lift up and pull out
control panel assembly carefully from the cavity.
D. PCB ASSEMBLY REMOVAL
1) Remove the control panel assembly from the cavity. (Refer to control panel
assembly removal on previous step.)
2) Remove screws which hold the PCB SUB ASS ’Y to the control panel.
Remove the screw
Lift up and pull out control panel

5-5
E. DOOR ASSEMBLY / REMOVAL
1) Open the door.
2) Check door harness connector (1) disconnected that connector locate on
Upper cavity.
3) Remove screw on harness cover and remove Harness cover after remove
screw with screwdriver.(2) on base plate around lower hinge.
4) Push locker under upper hinge to left using screwdriver.
CAUTION: Be careful not to damage door seal plate by screwdriver.
5) Lift up and push the door.
NOTE:
1. After replacing the door, be sure to check that the primary switch, monitor
switch, and secondary switch operate normally.
2. After replacing the door, check for microwave energy leakage with a survey
meter. Microwave energy must be below the limit of 4 mW/cm
2
. (with a 275 ml
water load)
3. When mounting the door assembly to the oven assembly, be sure to adjust the
door assembly parallel to the chassis. If the door assembly is not mounted
properly, microwaves may leak from the clearance between the door and the
oven.
(1)
(2)
Remove door assembly
Spacer
Remove door assembly

5-6
F. AIR DUCT ASSEMBLY / REMOVAL
1) Remove the mounting screw to the magnetron.
G. MAGNETRON REMOVAL
1) Disconnect the lead wire from the magnetron.
2) Carefully remove the mounting screws holding the magnetron and the
waveguide.
3) Remove the magnetron ASS’Y until the tube is clear from the waveguide.
NOTE:
1. When removing the magnetron, make sure its dome does not hit any
adjacent parts, or it may be damaged.
2. When replacing the magnetron, be sure to install the magnetron gasket in
the correct position and be sure that the gasket is in good condition.
3. After replacing the magnetron, check for microwave leakage with a survey
meter around the magnetron. Microwave energy must be below the limit of
5 mW/cm
2
. (With a 275 ml. water load). Make sure that gasket is rigidly
attached to the magnetron. To prevent microwave leakage, tighten the
mounting screws properly, making sure there is no gap between the
waveguide and the magnetron.
4. Magnetron is hot, after operation of oven.
H. REMOVING THE TURNTABLE MOTOR
1) Remove the turntable, rotating ring and shaft.
2) Lay the unit down on its back.
3) Remove the turntable motor cover.
The turntable base cover is easily removed by pinching the eight parts with
a wire cutting.
4) Disconnect the leadwire from the turntable motor terminals.
5) Remove the screw securing the turntable motor to the oven cavity ASS’Y.
6) After repairing the motor, rotate the removed turntable motor cover.
7) Fit the turntable motor cover’s projecting part to the base plate slit.
8) The taptite screw shall be used when a turntable motor cover is secured
with a screw.
NOTE:
1. Remove the wire lead from the turntable motor VERY CAREFULLY.
(Removing cover can cause sharp burr. Use gloves.)
2. Be sure to grasp the connector, not the wires, when removing.
Waveguide
Air duct
Magnetron
Magnetron
Gasket
Magnetron
Dome
Waveguide
Bracket
Wire Leads
Turntable Motor
Taptite Screw

5-7
I. INVERTER REMOVAL
1) Disconnect the lead wire from magnetron, Harness, Controller PCB
2) Remove the ground screw.
3) Remove the 4 screws holding the inverter on baseplate.
J. FAN MOTOR ASSEMBLY REMOVAL
1) Disconnect the lead wire from fan motor
2) Remove the three screw holding the suction guide ASS'Y to the oven cavity
3) Remove two earth wire(noise filter & power cord) and remove all connector on
noise filter.
4) Lift up slowly the suction guide assembly from cavity.
5) Pull Fan from Fan motor to remove it.
6) Remove fan from motor and two screws holding the fan motor ASS'Y to the
suction guide ASS'Y.
K. INTERLOCK SYSTEM
1) INTERLOCK MECHANISM
The door lock mechanism is a device which has
been specially designed to eliminate microwave activity when the door is
opened during cooking and thus to prevent the danger resulting from the
microwave leakage.
PRIMARY
SWITCH
MONITOR
SWITCH
SECONDARY
SWITCH
2) INSTALLATION AND ADJUSTMENT OF THE LATCH BOARD TO THE
OVEN ASSEMBLY
• Mount the latch board to the oven assembly.
• Tighten the mounting screw.
• Check for play in the door by pulling the door. Door movement should
be less than 0.5 mm. (1/64 inch)
Make sure that the latch moves smoothly after adjustment is completed and
that the screws are tight. Make sure the primary, monitor, and secondary
switches operate properly by following the continuity test procedure.
H.V.
Transformer
Fan Motor
Suction
Guide

5-8
L. INVERTER REMOVAL FROM SUPPORTER
1) Remove the upper inverter supporter both side using Flat blade
screwdriver.
2) Remove the screw and washer using Phillips screwdriver
3) Push the inverter backward and remove the inverter.
LMC1575BD /00
LMC1575ST /00
LMC1575SW /00
LMC1575SB /00
LMC1575BD /01
LMC1575ST /01
LMC1575SW /01
LMC1575SB /01