LG 3828W5S5177 Service Manual

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MICROWAVE OVEN
SERVICE MANUAL
MODEL: MH-1144DP
CAUTION
BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : 3828W5S5177
Printed in Korea
SAFETY PRECAUTIONS
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.
CONTENTS
(Page)
SAFETY PRECAUTIONS
SPECIFICATIONS
CAUTIONS
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INSTALLATIONS
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OPERATING INSTRUCTIONS
FEATURES
CONTROL PANEL
OPERATING SEQUENCE
SCHEMATIC DIAGRAM
CIRCUIT DESCRIPTION
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SERVICE INFORMATION
TOOLS AND MEASURING INSTRUMENTS
MICROWAVE LEAKAGE TEST
MEASUREMENT OF MICROWAVE POWER OUTPUT
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Inside front cover
1-1
2-1
3-1
4-1
4-1
4-1
4-2
4-3
4-4
5-1
5-1
5-1
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5-3
DISASSEMBLY AND ADJUSTMENT
INTERLOCK CONTINUITY TEST
COMPONENT TEST PROCEDURE
TROUBLE SHOOTING
EXPLODED VIEW
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REPLACEMENT PARTS LIST
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5-3
5-7
5-8
5-12
6-1
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7-1
SPECIFICATIONS
Back Side
ITEM
MODEL
Power Requirement
Power Output
Microwave Frequency
Magnetron
Timer
Outside Dimensions
Cavity Dimensions
Net Weight
Shipping weight
Control Complement
DESCRIPTION
MH-1144DP
120 Volts AC 60 Hz Microwave 1400W Grill 1000W Single phase, 3 wire grounded
1000 Watts full microwave power (IEC60705)
2450 MHz
2M246 - 050GF
0 ~ 99 min. 99 sec
530 (W) x 315 (H) x 394 (D) (mm)
348 (W) x 242 (H) x 373 (D) (mm)
14 kg (approx.)
16 kg (approx.)
Touch Control System
Clock : 1:00 - 12:59
Microwave Power for Variable Cooking
Power level
HIGH ............................... Full power throughout the cooking time
9 (Saute)
7 (Med.-High)
5 (Med.-Low)
3 (Low)
1 (Warm)
..........................
..................
...................
............................
.........................
approx. 90% of Full power, 8 (Reheat)
approx. 70%, 6 (Medium)
approx. 50%, 4 (Defrost)
approx. 30%, 2 (Simmer)
approx. 10%
.......
approx. 80%
......
approx. 60%
.......
approx. 40%
.......
approx. 20%
Rating Label Location
Accessories
This microwave oven is designed for household use only.
It is not recommended for commercial purposes.
Owner's manual
Glass turntable
Rotating ring
Grill rack
1-1
CAUTIONS
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 high voltage capacitor. When replacing or checking, you must discharge the high voltage capacitor by shorting across the two terminals with an insulated screwdriver.
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 the dome of the tube whenever installing the magnetron.
ANTENNA
Gasket
• 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.
COOLING FIN
FILAMENT TERMINALS
MAGNETRON CHASSIS GROUND
MAGNETRON
THE OVEN IS TO BE SERVICED ONLY BY PROPERLY QUALIFIED SERVICE PERSONNEL.
2-1
INSTALLATIONS
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. (The control panel side of the oven is the heavy side. Use care when handling.)
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, etc., to prevent interference.
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.
PREFERRED METHOD
ENSURE PROPER GROUND
EXISTS BEFORE USE
TEMPORARY METHOD (ADAPTER PLUGS NOT PERMITTED IN CANADA)
ALIGN LARGE PRONGS/SLOTS
10cm
ENSURE PROPER GROUND AND FIRM CONNECTION BEFORE USE
3-1
OPERATING INSTRUCTIONS
Grill Rack
Rotating Ring
FEATURES
CONTROL PANEL
15
14
12
1. INDICATORS
2. LATIN MENU
3. OPTION
1
2
16
5
8 9
4
6
7
3
10
11
13
4. NUMBER: Used to set for time of day, cooking time,
power level or defrost weight.
5. AUTO DEFROST: Used to select the desired auto
weight defrost programmed with weight pad.
6. Q-DEFROST
7. MICRO: Used to cook food for a desired time.
8. COMBI: Used to cook food by microwave and
combination.
9. GRILL: Used to cook food by microwave and grill.
10. POWER: Used to select power level for cooking.
11. CLOCK: Used to set the time of day.
12. STOP/CLEAR: Used to stop oven and clear all
entries except time of day.
13. START/QUICK START: One tap allows oven to
begin functioning.
14. HOLD WARM
15. ONE TOUCH CONTROL: Used to cook the foods
listed by one touch.
16. MENU DIET
4-1
OPERATING SEQUENCE
The following is a description of component functions during oven operation.
1. SETTING THE CLOCK
PAUSA/BORRAR
ex.) To set 4:30, touch number key [4],[3], and [0].
NOTE: 1) This is a 12 hour clock.
2) Clock will operate as long as power is applied to the oven.
RELOJ RELOJNUMBER
2. CANCEL FUNCTION
Touch the pad whenever you need to cancel an entry or a function currently in use. The display will either return to the last item entered or to the clock.
PAUSA/BORRAR
3. ADD 30 SECOND
PAUSA/BORRAR
INICIO
4. LATIN MENU
PAUSA/BORRAR
NOTE: Heat only 1 package at a time
FRIJOLES
NUMBER
INICIO
7. AUTO WEIGHT DEFROST COOKING
PAUSA/BORRAR
AUTO DESCONG
POR PESO
NUMBER OF
WEIGHT
NUMBER
8. CHILD LOCK
This oven has a CHILD LOCK feature
TO SET CHILD LOCK
Touch the pad
Touch and hold PARAR/BORRAR pad LOCK
appear on the display.
TO CANCEL CHILD LOCK
Touch the pad
Touch and hold PARAR/BORRAR pad LOCK
disappears.
PAUSA/BORRAR
PAUSA/BORRAR
9. GRILL COOKING
PAUSA/
BORRAR
DORADOR
Desired cooking
time
INICIO
5. MICRO COOKING
PAUSA/BORRAR
MICRO
NUMBER INICIO
NUMBER
6. MULTI-STAGE COOKING
1ST STAGE
PAUSA/BORRAR
2ND STAGE
TIME
NUMBER
TIME
NUMBER INICIO
NUMBER
NUMBER
POTENCIA
POTENCIA
POTENCIA
10. COMBI COOKING
PAUSA/
BORRAR
COMBI
Desired cooking
time
INICIO
4-2
SCHEMATIC DIAGRAM
PRIMARY SWITCH
FUSE
THERMOSTAT
OVEN
8
7
6
5
4
312
* NOTE : DOOR IS OPENED.
INPUT
PK
GN
POWER
SECONDARY
WH
SWITCH
WH
CN1
RY2
BL
RY3
BL
YL
L
N
GN
GN
BL
BK
BK
BK
MICOM CONTROLLER
RY1
PT1
BK
MONITOR SWITCH
MAGNETRON
OVEN LAMP
FAN MOTOR
TURNTABLE MOTOR
BL:BLUE
BK:BLACK
WH:WHITE
WH
WH
WH
BL
BN:BROWN
YL:YELLOW
GN:GREEN
RD:RED
PK:PINK
WH
WH
H.V.DIODE
H.V.
CAPACITOR
RD
GRILL HEATER ASSY
GRILL HEATER ASSY
BK
BK
YL
YL
YL
RD
YL
H.V TRANSFORMER
RD
FFA
RD
O.L
F.
M
T.T.M
SE R
U TAE
F LAI
C EPS
ETAR
O P R OCNI M
A R G AID CI
T AMEHC
S SIH
T NO S
A ERA D
E D AH
S EHT :ETO
N Y
T EFA
S T
N AT
R OP
MI
DN A
,K C
O HS LA
CI R
T CEL
E ,E
RIF ,NOITAID
AR
EV A
WORCIM M
OR F N
OI TCET
O R P R
O F T
N A TR
O PMI
AP D
EI FI CE
PS
S
RER
U TCAFUNAM YLNO
T AHT
L AITNESSE SI TI GNICIVRES NEHW .SDRAZAH
S TR
GA I
D C
I TA
M E H C S E
H T FO S
A ERA DED
A HS EHT NI STNEN
O PM
OC L
ACI
TIRC
E HT ROF DE
SU E
B
.
MA R
D N A
S TN
E N O PM
OC
F O
SEUL
A V
E HT ,M
A R G AI
D CITAM
EHC
S CIS
A B SI SI
H T E
CN IS :ECITON
.TNEM
E VOR
PMI R
O F
E G N AH
C O
T TC
E JBU
S
ERA SNOITCENNOC LAITRAP EMOS
4-3
CIRCUIT DESCRIPTION
L
FUSE
H.V.
TRANS-
FORMER
RELAY 2
MICOM CONTROLLER
SECONDARY SWITCH
PRIMARY
SWITCH
N
MONITOR
SWITCH
GENERAL DETAILS
The low voltage transformer 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 PAD
The coil of the relay is energized by the micom controller.
Power input is supplied to the high voltage transformer through the fuse to the primary switch and relay 2.
Turntable rotates.
power of microwave oven as POWER LEVEL.
(refer to page 1-1)
WHEN THE DOOR IS OPENED DURING COOKING
Both the primary switch and relay 2 are cut off primary winding voltage of the high voltage transformer.
ON-OFF of relay 2 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 fails to open, the fuse opens due to the large current surge caused by the monitor switch activation, which in turn stops magnetron oscillation.
PRIMARY
FUSE
L
N
SWITCH
MONITOR
SWITCH
H.V.
TRANS-
FORMER
The fan motor rotates and cools the magnetron by blowing the air (coming from the intake on the baseplate).
The air is also directed into the oven to exhaust the vapor in the oven through the upper plate.
Cooking time starts counting down.
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 high voltage diode and charging of the high voltage capacitor.
The negative 4000 Volts DC is applied to the filament of the magnetron.
WHEN THE OVEN IS SET AT ANY LEVEL EXCEPT MAXIMUM.
The micom controller controls the ON-OFF time of relay
2 by the applied signal to vary the average output
RELAY 2
MICOM CONTROLLER
SECONDARY SWITCH
WHEN TOUCHING THE START KEY WITH THE GRILL COOKING FUNCTION SELECTED
The contacts of the primary switch and the secondary switch close the circuit.
A.C. voltage is applied to the grill heater through grill thermostat as shown by the solid line.
Turntable rotates.
OVEN
THERMOSTAT
L
L
G -Y
N
E
N
RELAY 3
The fan motor rotates.
The air is also directed into the oven to exhaust the
vapor in the oven through the base plate and upper plate.
GRILL
HEATER
4-4
SERVICE INFORMATION
TOOLS AND MEASURING INSTRUMENTS
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
MICROWAVE LEAKAGE TEST
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 and CDRH (Center for Devices and Radiological Health) immediately.
NOTE: Address on CDRH
Office of Compliance(HFZ-312) Center for Devices and Radiological Healthe 1390, Piccard Drive, Rockville. MD 20850
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/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(3
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)
1
/2
in.)
MEASURING MICROWAVE ENERGY LEAKAGE
Pour 275±15 cc 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 2450 MHz and use it following the manufacturer's recommended test procedure to assure correct result.
When measuring the leakage, always use the 2- inch (5 cm) 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)
5-1
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