LG MB-393T Service Manual ▷ View online
6-7
56170D
63302A
63303A
WTT021
WSZ002
65006B
948501
BASE PLATE PARTS
CAUTIONS
• Be sure to check microwave leakage prior to
servicing the oven if the oven is operative prior to
servicing.
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/cm
certified oven unit found to have a microwave
emission level in excess of 5 mW/cm
2
and 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.
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.
- 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
4 mW/cm
emitted by the microwave oven should not exceed
4 mW/cm
2
. Always start measuring of an unknown field
to assure safety for operating personnel from radiation
leakage.
leakage.
MEASURING MICROWAVE ENERGY
LEAKAGE
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.
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.
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
• Measure the microwave radiation using and
electromagnetic radiation monitor by holding the
probe perpendicular to the surface being measured
probe perpendicular to the surface being measured
Move probe along shaded area
Probe scanning speed
Less than 2.5 cm/sec
( 1in/sec)
Less than 2.5 cm/sec
( 1in/sec)
5-1
SERVICE INFORMATION
TOOLS AND MEASURING INSTRUMENTS
MICROWAVE LEAKAGE TEST
NECESSARY TOOLS
Tools normally used for TV servicing are sufficient.
Standard tools are listed below.
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
• Long nose pliers
• Phillips screwdriver
• Flat blade screwdriver
• Wrench (size 5mm)
• Nutdriver (size 5mm)
• Adjustable wrench
• Soldering iron
• Solder
• Vinyl insulation tape
• Polishing cloth
NECESSARY MEASURING INSTRUMENTS
• TESTER(VOLTS-DC, AC., Ohmmeter)
• Microwave survey meter
• Microwave survey meter
- Holaday HI-1500
HI-1501
- Narda 8100
8200
• Inch scale
• 600 cc non conductive material beaker (glass or plastic),
• 600 cc non conductive material beaker (glass or plastic),
inside diameter: approx. 8.5 cm(3
1
/2
in.)
• Cylindrical and made of borosilicate glass vessel.
max. thickness: 3 mm
outside diameter: approx. 190mm
height: approx. 90mm
outside diameter: approx. 190mm
height: approx. 90mm
• Glass thermometer: 100°C or 212°F (1 deg scale)
5-10
COMPONENTS
TEST PROCEDURE
RESULTS
FUSE
HEATER ELEMENT
(Wire leads removed.)
(Wire leads removed.)
GRILL THERMOSTAT
OVEN THERMOSTAT
MAGNETRON
THERMOSTAT
MAGNETRON
THERMOSTAT
Check for continuity of the fuse with an
multi-meter.
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.
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.
NOTE: Make sure heater is fully cooled when tested.
Measure the resistance.
(Multi-meter scale: Rx1)
(Multi-meter scale: Rx1)
Normal:
*Grill heater
*Grill heater
Approx. 50
Ω
(at 20 ~ 30°C)
Normal: more than 200 M
Ω
Normal Abnormal
Measure the resistance with 500V-100M ohm
insulation resistance meter.
insulation resistance meter.
0°C~Approx.90°C Approx.90°C
0°C~Approx.145°C Approx.145°C
5-11
COMPONENTS
TEST PROCEDURE
RESULTS
TIMER MOTOR
(Wire leads removed)
FAN MOTOR
(Wire leads removed)
(Wire leads removed)
TURNTABLE
MOTOR
(Wire leads removed)
MOTOR
(Wire leads removed)
Check for continuity of timer motor with an
ohm-meter.
(Remove wire leads from timer motor)
ohm-meter.
(Remove wire leads from timer motor)
Measure the resistance.
(Ohm-meter scale: R x 1)
(Ohm-meter scale: R x 1)
Measure the resistance.
(Ohm-meter scale: R x 1000)
(Ohm-meter scale: R x 1000)
Normal:
Abnormal:
∞
or several
Ω
Normal: Approx. 100~200
Ω
Abnormal:
∞
or several
Ω
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
• WHEN REMOVING THE WIRE LEADS FROM THE PARTS, BE SURE TO GRASP THE
CONNECTOR, NOT THE WIRES.
A
B
C
Turn On Turn Off
A
B
Grill Switch
Microwave Switch
Approx. 22 K
Ω
Note : A is timer ON, OFF
switch.
B is power supply
terminal of the timer
motor.
B is power supply
terminal of the timer
motor.
A ~ B A ~ C
30 ~ 50
Ω
300~500
Ω
A
B
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