LG MS-1905C User manual

MICROWAVE OVEN
SERVICE MANUAL
MODEL: MS-1905C
CAUTION
BEFORE SERVICING THE UNIT, READ THE
SAFETY PRECAUTIONS IN THIS MANUAL.

1-1
This microwave oven is designed for household use only.
It is not recommended for commercial purposes.
SPECIFICATIONS
ITEM
MODEL
Power Requirement
Power Output
Microwave Frequency
Magnetron
Timer
Outside Dimensions
Cavity Dimensions
Net Weight
Shipping weight
Control Complement
Nameplate Location
Accessories
Left side of
control panel Back cover
OR
DESCRIPTION
MS-1905C
230 Volts AC 50 Hz
Single phase, 3 wire grounded
Microwave 1,150W
microwave power (IEC705): 750W
2,450 MHz
2M214 - 39F, 2M218J, 2M254J
0 ~ 60 min.
483 (W) x 285 (H) x 334(D) mm
300(W) x 193(H) x 316 (D) mm
13.7 kg (approx.)
15.1 kg (approx.)
Microwave Power for Variable Cooking
Power level
MAX
600W
360W
DEFROST
90W
Owner's manual & Cooking guide
Glass turntable
Rotating Rest

4-1
FEATURES
OPERATING INSTRUCTIONS
Oven Front Plate
Window Door Screen
Door Seal
Control Panel
Door Open Button
Safety Door Lock System
Turntable
Rotating Rest
CONTROL PANEL
90
360
600
max
01
2
3
4
5
6
7
8
9
10
20
30
40
50
60
defrost
1
2
3
1. POWER CONTROL KNOB: Used to select the desired power level for cooking.
2. TIMER KNOB: Used to set the cooking time.
3. DOOR OPEN BUTTON: Press to open the door.

OPERATING SEQUENCE
Microwave Cooking
1. Open the oven door, place the food on the
turntable in the oven, and close the oven door.
2. Set the microwave power selector to the desired
power level. There are five power levels from 90W
to MAX. The power selector can be set to any one
of these positions.
3. Set the timer to the desired cooking time. The
turntable begins to rotate and cooking starts. At the
end of cooking time you will hear a single ring
sound, and the lamp is turn off.
NOTE:
• Each number represents minutes. To ensure
accurate timing, it is advisable to turn the timer knob
slightly passed the desired cooking time and then
back to the proposed setting.
• Press the door opener to check the cooking
condition during oven operation. Opening the door
during oven operation automatically turns off the
oven and stops the timer. If cooking is to continue,
close the door. Cooking will be resumed until the full
cooking time has elapsed.
4-2
POSITIONS
MAX
600W
360W
DEFROST
90W

4-3
SCHEMATIC DIAGRAM
IMPORTANT SAFETY NOTE: THE SHADED AREAS ON THIS SCHEMATIC DIAGRAM INCORPORATE SPECIAL FEATURES IMPORTANT FOR PROTECTION FROM MICROWAVE RADIATION, FIRE, ELECTRICAL SHOCK, AND HAZARDS. WHEN SERVICING IT IS ESSENTIAL THAT ONLY MANUFACTURER'S SPECIFIED PARTS BE USED FOR THE CRITICAL COMPONENTS IN THE SHADED AREAS OF THE SCHEMATIC DIAGRAM.
NOTICE: SINCE THIS IS BASIC SCHEMATIC DIAGRAM, THE VALUES OF COMPONENTS AND SOME PARTIAL CONNECTIONS ARE SUBJECT TO CHANGE FOR IMPROVEMENT.
NOISE FILTER
MONITOR
RESISTOR
A.C RELAY

4-4
CIRCUIT DESCRIPTION
• As the door is closed, the contact of MONITOR
SWITCH opens. This switch creates the short circuit to
blow fuse during operation under abnormal condition.
(ie, should the contacts of primary and secondary
switch fail to open the circuit)
• The latches are secured by latch board. The oven light
turns on while the oven is in operation.
WHEN MICROWAVE POWER LEVEL
AND COOKING TIME SET
• The contacts of the timer switch changes to ON
position when the timer knob is rotated.
(While power control knob is set at “Full Power”)
• The contacts of primary and secondary switch close
the circuit.
• Input Volts AC. is applied to the high voltage
transformer through power control switch as shown by
the solid line.
• Turntable rotates.
• The fan motor rotates and cools the magnetron by
blowing the air (coming from the intake holes on the
baseplate) over the magnetron.
• The air is also directed into the oven to exhaust the
vapor in the oven through the upper plate.
• Timer starts rotating.
• 3.2 volts AC is generated from the filament winding of
the high voltage transformer. This 3.2 volts is applied
to the magnetron to heat the magnetron filament
through two noise preventing choke coils.
A high voltage of approximately 2100 volts AC is
generated in the secondary of the high voltage
transformer which is increased by the action of the
diode and charging of the high voltage capacitor.
The negative DC voltage is then applied to the filament
of the magnetron
WHEN THE DOOR IS OPENED DURING
COOKING
• Both primary switch and secondary switch open to cut
off the primary winding voltage to the high voltage
transformer to stop microwave oscillation.
• Timer, turntable and fan motor stop.
• As the door is opened, if the contact of primary and
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
SECONDARY
SWITCH
MONITOR
SWITCH
MONITOR
RESISTOR
L
N
H.V.T
RELAY
TIMER
SWITCH
POWER
CONTROL
SWITCH
FUSE
PRIMARY
SWITCH
SECONDARY
SWITCH
L
N
H.V.T
RELAY
TIMER
SWITCH
POWER
CONTROL
SWITCH
MONITOR
SWITCH
MONITOR
RESISTOR

MICROWAVE OVEN
SERVICE MANUAL
MODEL: MS-1905C
CAUTION
BEFORE SERVICING THE UNIT, READ THE
SAFETY PRECAUTIONS IN THIS MANUAL.

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
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
manufacturer, 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.
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(31/2 in.)
• 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)
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
( 1in/sec)
5-1
SERVICE INFORMATION
TOOLS AND MEASURING INSTRUMENTS
MICROWAVE LEAKAGE TEST

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 below Fig.)
- 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 removedless 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.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 possibly
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.
5-2
WARNING : AVOID CONTACTING ANY
HIGH VOLTAGE PARTS

• 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)°K 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°K.
• 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.
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) Remove the screws for the ground and securing the
control panel.
3) Disconnect the leadwire from RELAY(RY2) of the
PCB SUB ASS’Y.
4) Lift up and pull out control panel assembly carefully
from the cavity.
5) Disconnect the leadwire from connector(CN1) of the
PCB SUB ASS’Y.
CAUTION: DISCHARGE THE HIGH VOLTAGE
CAPACITOR BEFORE SERVICING
(refer to page 2-1)
5-3
WATER LOAD
TURNTABLE
securing screw
MEASUREMENT OF MICROWAVE POWER OUTPUT
P =
Remove the screw
Lift up and pull out control panel
DISASSEMBLY AND ADJUSTMENT

D. PCB ASSEMBLY REMOVAL
1) Remove the control panel assembly from the
cavity. (Refer to control panel assembly removal
on previous page.)
2) Remove screws which hold the timer motor to the
control panel.
3) Remove the timer motor.
4) Remove the power control knob.
E. DOOR MAIN ASSEMBLY REMOVAL
1) Open the door.
2) Remove the choke cover very carefully with a
flat-blade screwdriver.
CAUTION : Be careful not to damage door seal plate
by screwdriver.
3) 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 5 mW/cm. (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. Also adjust so the door has no play
between the inner door surface and oven frame
assembly. If the door assembly is not mounted
properly, microwaves may leak from the clearance
between the door and the oven.
5-4
Release
Lever
Control Panel Timer Motor
Power Control
Knob
Timer Knob
Door Open Button
Button Spring
Remove choke cover
Spacer

F. MAGNETRON REMOVAL
1) Disconnect the leadwire from the magnetron.
2) Carefully remove the mounting screws holding the
magnetron and the waveguide.
3) Remove the magnetron assembly 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/cm2. (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.
5-5
Magnetron
Waveguide
Magnetron
Gasket
Magnetron
Dome
Waveguide
Bracket
G. SUCTION GUIDE MAIN ASSEMBLY
NOTE: Suction Guide Main ASS’Y consists of Latch
Board ASS’Y and Suction Guide ASS’Y. To repair any of
them, should be removed first Suction Guide Main
ASS’Y.
1) Disconnect the leadwire from the high voltage
transformer primary terminal, thermostat, noise filter
ASS’Y, and turn table motor connector.
2) Remove three screws holding the Suction Guide Main
ASS’Y to oven cavity.
3) Open the suction guide cover.
4) Rotate right and pull out Suction Guide Main ASS’Y
from the oven.
Screw
Remove magnetron
Wave guide and magnetron
Remove screw
Open the suction guide cover

H. LATCH BOARD ASSEMBLY AND
SUCTION GUIDE ASSEMBLY
NOTE: Suction Guide Main ASS’Y consists of Latch
Board ASS’Y and Suction Guide ASS’Y. To repair any of
them, should be removed first Suction Guide Main
ASS’Y.
1) Remove the screw.
2) Disconnect the leadwire.
5-6
Rotate right
and pull out
Latch board ASS'Y
Connecting screw
I. FAN MOTOR ASSEMBLY REMOVAL
NOTE: Suction Guide Main ASS’Y consists of Latch
Board ASS’Y and Suction Guide ASS’Y. To repair any of
them, should be removed first Suction Guide Main
ASS’Y.
1) Disconnect the leadwire from fan motor.
2) Remove the fan.
3) Remove the two screws holding the fan motor
assembly to the suction guide ass’y.
Fan Motor ASS'Y Suction
Guide
J. HIGH VOLTAGE TRANSFORMER
REMOVAL
1) Discharge the high voltage capacitor.
2) Disconnect the leadwire from magnetron, high voltage
transformer, and capacitor.
3) Remove the screw holding the high voltage
transformer to the baseplate.
Pull out suction guide Main ASS’Y
Remove the screw

K. HIGH VOLTAGE CAPACITOR AND
DIODE REMOVAL
1) Discharge the high voltage capacitor.
2) Disconnect the leadwire from the high voltage
capacitor.
3) Remove the screw holding the high voltage capacitor
bracket (refer to high voltage transformer removal
on previous page, FIG.1).
L. REMOVING THE TURNTABLE MOTOR
1) Remove the turntable.
2) Remove the rotating ring ass’y by hand.
3) Remove the turntable motor cover.
The turntable base cover is easily removed by
pinching the six parts with wire cutting pliers.
4) Disconnect the leadwire from the turntable motor
terminals.
5) Remove the screw securing the turntable motor to
the oven cavity assembly.
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.
NOTE:
1. Remove the wire lead from the turntable motor
VERY CAREFULLY.
2. Be sure to grasp the connector, not the wires,
when removing.
5-7
Wire Leads
Turntable Motor
M. INTERLOCK SYSTEM
1) INTERLOCK MECHANISM
The door lock mechanism is a device which has
been specially designed to eliminate completely
microwave activity when the door is opened during
cooking and thus to prevent the danger resulting
from the microwave leakage.
2) MOUNTING OF THE PRIMARY/MONITOR/
SECONDARY SWITCHES TO THE LATCH
BOARD
PRIMARY
SWITCH
ADJUSTMENT
DIRECTION
MONITOR
SWITCH
SECONDARY
SWITCH
3) INSTALLATION AND ADJUSTMENT OF THE
LATCH BOARD TO THE OVEN ASSEMBLY
• Mount the latch board to the oven assembly.
• Adjust the latch board in the arrow direction so that
oven door will not have any play in it when the door
is closed.
• Tighten the mounting screw.
• Check for play in the door by pushing the door
release button. Door movement should be less
than 0.5 mm. (1/64 inch)
Don't push the door release button while making
adjustment. Make sure that the latch moves
smoothly after adjustment are completed and that
the screws are tight. Make sure the primary,
monitor, and secondary switches operate properly
by following the continuity test procedure.
* After repairing Turn Table Motor. Be sure to
remove all sharp edges around the motor cover,
and notify to customers to be careful.
CAUTION: CHECK THE CORRECT POSITION
MAGNETRON
H.V. TRANSFORMER
PRIMARY CIRCUIT PROTECTOR
H.V. CAPACITOR
H.V.
DIODE
FIG. 1

A. PRIMARY INTERLOCK SWITCH TEST
When the door release button is depressed slowly
with the door closed, an audible click should be
heard at the same time or successively at
intervals. When the button is released slowly, the
latches should activate the switches with an
audible click.
If the latches do not activate the switches when
the door is closed, the switches should be a
adjusted in accordance with the adjustment
procedure. Disconnect the wire lead from the
primary switch. Connect the ohmmeter leads to
the common (COM) and normally open (NO)
terminal of the switch. The meter should indicate
an open circuit in the door open condition.
When the door is closed, the meter should
indicate a closed circuit.
When the primary switch operation is abnormal,
make the necessary adjustment or replace the
switch only with the same type of switch.
B. SECONDARY INTERLOCK SWITCH TEST
Disconnect the wire lead from the secondary
switch.
Connect the ohmmeter leads to the common
(COM) and normally open (NO) terminals of the
switch. The meter should indicate a open circuit in
the door open condition. When the door is closed,
meter should indicate an closed circuit. When the
secondary switch operation is abnormal, make the
necessary adjustment or replace the switch only
with the same type of switch.
C. MONITOR SWITCH TEST
Disconnect the wire lead from the monitor switch.
Connect the ohmmeter leads to the common
(COM) and normally closed (NC) terminals of the
switch. The meter should indicate closed circuit in
the door open condition. When the door is closed,
meter should indicate an open circuit. When the
monitor switch operation is abnormal, replace with
the same type of switch.
NOTE: After repairing the door or the interlock
system, it is necessary to do this continuity
test before operating the oven.
5-8
WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION
EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS.
TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR PRIMARY SWITCH
TYPE NO. SZM-V 16-FA-61 OR VP-531A-OF FOR MONITOR SWITCH
TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR SECONDARY SWITCH
COMPONENTS TEST PROCEDURE RESULTS
SWITCHES Check for continuity of the Door Door
(Wire leads removed) switch with an Ohm-meter open closed
Primary
Switch
Monitor
Switch
NOTE : After checking for the continuity of switches, make sure that are
connected correctly.
NO
COM
NC
COM
NO
COM
NO
COM
INTERLOCK CONTINUITY TEST
Secondary
Switch

5-9
CAUTIONS
1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE
OUTER CASE FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER
OF WATER IN CONTAINER) IN THE OVEN.
COMPONENTS TEST PROCEDURE RESULTS
HIGH VOLTAGE
TRANSFORMER
(Wire leads removed)
MAGNETRON
(Wire leads removed)
1. Measure the resistance.
(Ohm-meter scale: Rx1 and Rx100)
• Primary winding
• Secondary winding
• Filament winding
2. Measure the resistance.
(Ohm-meter scale: Rx1000)
• Primary winding to ground
• Filament winding to ground
1. Measure the resistance.
(Ohm-meter scale: Rx1)
• Filament terminal
2. Measure the resistance.
(Ohm-meter scale: Rx1000)
• Filament to chassis
Approx.: 2 ohm
Approx.: 125 ohm
Less than: 1 ohm
Normal: Infinite
Normal: Infinite
Normal: Less than 1 ohm
Normal: Infinite
PRIMARY
TERMINAL
SECONDARY
TERMINAL
FILAMENT
WINDING
TERMINAL
COMPONENT TEST PROCEDURE

5-10
COMPONENTS TEST PROCEDURE RESULTS
HIGH VOLTAGE
CAPACITOR
HIGH VOLTAGE
DIODE
NOTE :
Some inexpensive meters
may indicate infinite
resistance in both direction.
Measure the resistance.
(Ohm-meter scale: Rx1000)
• Terminal to terminal.
Measure the resistance.
(Ohm-meter scale: Rx1000)
• Terminal to case.
Measure the continuity (Forward).
(Ohm-meter scale: Rx10000)
Measure the continuity (Reverse).
(Ohm-meter scale: Rx10000)
Normal: Momentarily indicates
several ohms, and
then gradually returns
to infinite.
Normal: Infinite.
Normal: Continuity.
Abnormal: Infinite.
Normal: Infinite.
Abnormal: Continuity.
NOTE: When testing the magnetron, be sure to install the magnetron gasket
in the correct position and be sure that the gasket is in good condition.
Antenna
Gasket
Chassis
Filament

COMPONENTS TEST PROCEDURE RESULTS
5-11
MAIN FUSE Check for continuity of the fuse with an
multi-meter.
NOTE: If the fuse is blown, check the primary, the secondary, and the monitor
switches, H.V.D. and H.V.C. before replacing the fuse.
If the fuse is blown by improper switch operation replace the defective switch
and the fuse at the same time. Replace just the fuse if the switches operate
normally.
Normal Abnormal

COMPONENTS TEST PROCEDURE RESULTS
5-12
TIMER MOTOR
(Wire leads removed)
FAN MOTOR
(Wire leads removed)
TURNTABLE
MOTOR
(Wire leads removed)
Check for continuity of timer motor with an
ohm-meter.
(Remove wire leads from timer motor)
Measure the resistance.
(Ohm-meter scale: R x 100)
Measure the resistance.
(Ohm-meter scale: R x 1000)
Note: A is timer ON, OFF
switch.
B is power supply
terminal of the timer
motor.
C is defrost switch.
Normal: Approx. 350 ~ 400 ohm
Abnormal: Infinite or several
ohm.
Normal: Approx. 16 Kohm
Abnormal: Infinite or several
ohm.
NOTE : • A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS
SERVICED FOR ANY REASON.
• MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION.
• WHEN REMOVING THE WIRE LEADS FROM THE PARTS, BE SURE TO GRASP THE
CONNECTOR, NOT THE WIRES.
C
(2-3)
B
(3-M)
A
(3-4)
A
BApprox. 22 Kohm
Turn On Turn Off

TROUBLE SHOOTING
WHEN YOU GET A COMPLAINT FROM YOUR CUSTOMER, EVALUATE THE COMPLAINT CAREFULLY. IF
THE FOLLOWING SYMPTOMS APPLY, PLEASE INSTRUCT THE CUSTOMER IN THE PROPER USE OF THE
MICROWAVE OVEN. THIS CAN ELIMINATE AN UNNECESSARY SERVICE CALL.
5-13
CAUTIONS
1. Check grounding before checking for trouble.
2. Be careful of the high voltage circuit.
3. Discharge the high voltage capacitor. (See page 2-1)
4. When checking the continuity of the switches or of the high voltage transformer, disconnect one lead wire
from these parts and then check continuity with the AC plug removed. To do otherwise may result in a
false reading or damage to your meter.
CONDITION
Microwave oven
does not work. Inserting many plug into one
plug outlet and using
them at the same time
(causes overloading).
Microwave oven plug is not
inserted tightly.
Output power is too low. Low AC input voltage.
Food temperature is too low.
Using metallic ware and
allowing it to touch the oven
wall.
Sparks occur.
Inconsistent intensity of
microwave by their
characteristics.
1. Use plastic wrap or lid.
2. Stir once or twice while
cooking soup, cocoa or
milk, etc.
Uneven cooking.
Ceramic ware trimmed in
gold or silver powder is used.
Avoid using other electrical
appliances when you use the
microwave oven.
Insert microwave oven plug
securely.
Use the microwave oven at
adequate line voltage.
This may not be a defect.
It is possible that the food
should be cooked for a
longer time period.
Do not use metallic ware for
cooking except where noted
in the cooking guide.
Do not use any type of
cookware with metallic
trimming.
CAUSE REMEDY
Excessive weight on tray or
improperly balanced.
Distribute food evenly. Cook
smaller portions and,or
use lighter weight
cookware.
Turntable drags or makes
noise.