Related Manuals for LG MH-1355M
Summary of Contents for LG MH-1355M
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Page 1: Microwave Oven
Website: http://biz.lgservice.com MICROWAVE OVEN SERVICE MANUAL MODEL: MH-1355M MH-1356M MH-1357M CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. July, 1998 P/NO : 3828W5S6174 Printed in Korea... -
Page 2: Safety Precautions
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... -
Page 3: Table Of Contents
TABLE OF CONTENTS SPECIFICATIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4 CAUTIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5 INSTALLATIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 6 FEATURE DIAGRAM - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 7... -
Page 4: Specifications
SPECIFICATIONS Power Supply - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 120 VAC, 60 Hz Power Consumption - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1400 Watts (Microwave), 12A 1580 Watts (Convection), 13.2A Output - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - *850 Watts (Microwave) -
Page 5: Cautions
CAUTIONS Unlike other appliances, the microwave oven is MICROWAVE RADIATION high-voltage and high-current equipment. Personnel should not be exposed to the Though it is free from danger in ordinary use, microwave energy which may radiate from the extreme care should be taken during repair. magnetron or other microwave generating device if it is improperly used or connection. -
Page 6: Installations
INSTALLATIONS BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY. INSTALLING EARTHING INSTRUCTIONS 1. Empty the microwave oven and clean inside it with This microwave oven is designed to be used in a fully a soft, damp cloth. Check for damage such as earthed condition. -
Page 7: Feature Diagram
FEATURE DIAGRAM AIR VENTS SEE-THROUGH DOOR CONTROL PANEL SAFETY INTERLOCK SYSTEM TURNTABLE ROTATING RING ASM CONVECTION RACK Fig. 3 Remove your Microwave/Convection Oven and all material from the shipping carton. Your oven will be packed with the following material: Turntable - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 Each Rotating Ring Asm - - - - - - - - - - - - - - - - - - - - - - - - - - 1 Each Convection Rack - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 Each Cookbook - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 Each... -
Page 8: Control Panel
CONTROL PANEL INDICATOR LIGHTS- DISPLAY WINDOW- When cooking operations Used to show: are set, lights will go on • Time of day. indicating the cycle in which • Cooking time. your oven is cooking. • Cooking power level. • Cooking temperature. •... - Page 9 NOTE: 1. Beep Sound The beep sound is activated under the following conditions. Conditions Beep Sound Signal • When the control key is touched, • When the cooking stage is changed, • When the preheat is ended and the holding time is begun, •...
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Page 10: How The Microwave/Convection Oven Works
HOW THE MICROWAVE/ CONVECTION OVEN WORKS MICROWAVE COOKING Using microwave energy only, food is cooked quickly without altering its color or shape. The food is evenly cooked on a rotating turntable as the microwaves are produced by the magnetron. Power Control can be adjusted in 10 steps, enabling the various kinds of foods to cook at most desirable cooking power for the best Magnetron... -
Page 11: Cooking Flow Chart
COOKING FLOW CHART CLOCK HOLD AUTO STAGE 1 STAGE 2 STAGE 3 WARM WEIGHT DEFROST AUTO POPCORN REHEAT WEIGHT COMBINATION START Cooking procedure have five sequential programs. AUTO WEIGHT DEFROST STAGE 1 STAGE 2 STAGE 3 HOLD WARM Cooking program can be partially and independently selected. Example: AUTO WEIGHT DEFROST STAGE 1... -
Page 12: Operating Instructions
OPERATING INSTRUCTIONS TO SET THE TIME OF DAY “MICRO TIME” COOKING 1. When the oven is plugged in, the display window will 1. Touch MICRO TIME. show zero( :0) 2. Touch numbers for desired cooking time. 2. Touch CLOCK. 3. Touch MICRO POWER. 3. -
Page 13: Automatic Defrost By Weight
“COMBINATION” COOKING NOTE: • If you input over the acceptable weight, "E" will show 1. Touch COMBINATION HIGH or LOW. in the display window. It means error and the oven 2. Touch numbers for desired cooking time. does not operate. 3. -
Page 14: Child Lock
To Cancel Child Lock “POPCORN” 1. Touch “0” more than 2 seconds. 1. Put a micro-proof rack on the turntable. 2. Touch POPCORN. NOTE: 3. Touch START. • When you cancel Child Lock, STOP/CLEAR must always be touched before selection. NOTE: •... -
Page 15: Schematic Diagram
SCHEMATIC DIAGRAM SYSTEM 1: STAND-BY CONDITION Set up: Door is opened. Oven power cord is plugged into standard 120 volt ground outlet. Normal operation • Oven light turns on. THERMOSTAT FUSE (OVEN ) OVEN LAMP TURNTABLE MOTOR REL A Y 3 FAN MOTOR REL A Y4 CIRCULATION MOTOR... - Page 16 SYSTEM 2: MICROWAVE COOKING CONDITION Set up: Door is closed. START is touched. Normal operation • Oven light turns on. • Turntable operates. • Fan motor operates. THERMOSTAT FUSE ( OVEN ) OVEN LAMP TURNTABLE MOTOR REL A Y 3 FAN MOTOR REL A Y4 CIRCULATION MOTOR...
- Page 17 SYSTEM 3: CONVECTION COOKING CONDITION Set up: Door is closed. START is touched. Normal operation • Oven light turns on. • Turntable operates. • Fan motor and circulation motor operate. THERMOSTAT FUSE ( OVEN ) OVEN LAMP TURNTABLE MOTOR REL A Y 3 FAN MOTOR REL A Y4 CIRCULATION MOTOR...
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Page 18: Circuit Description
CIRCUIT DESCRIPTION • The low voltage transformer supplies the necessary WHEN THE OVEN IS SET AT SOME COOKING voltage to the micom controller when power cord is POWER EXCEPT MAX. COOKING POWER. plugged in. • Micom controller controls the ON-OFF time of the •... - Page 19 MAGNETRON TUBE MAGNETRON WITHOUT MAGNETIC FIELD • The magnetron tube is the heart of the microwave oven. It is basically a diode with the addition of a magnetic field. The magnetron tube assembly con- ANTENNA sists of cylindrical cathode (negative) terminal, CATHODE enclosed within a cylindrical anode (positive) termi- ELECTRONS...
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Page 20: Description And Function Of Components
DESCRIPTION AND FUNCTION OF COMPONENTS OVEN LAMP PRIMARY AND SECONDARY INTERLOCK SWITCHES (FIG. 11) The oven lamp illuminates the interior of the oven during cooking so that food can be seen without The primary interlock switch is mounted in the latch opening the door. - Page 21 CONVECTION COOKING SYSTEM (FIG. 12) CHAMBER ASSEMBLY (FIG. 12) Convection cooking is not performed by direct heat The air heated by the heating element is circulated from the heating elements, but by forced circulation of through the convection passage provided on the back the hot air produced by the heating elements located side of the oven by means of the convection fan which at the back side of the oven cavity.
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Page 22: Necessary Tools And Measuring Instruments
NECESSARY TOOLS AND MEASURING INSTRUMENTS NECESSARY TOOLS NECESSARY MEASURING INSTRUMENTS Tools normally used for TV servicing are sufficient. • Tester (Volt DC, AC-ohmmeter) Standard tools are listed below. • Inch scale • Diagonal pliers • Electromagnetic radiation monitor • Long nose pliers •... -
Page 23: Installation And Adjustment Of The Interlock System
INSTALLATION AND ADJUSTMENT OF THE INTERLOCK SYSTEM A. INSTALLATION CAUTION: FOR CONTINUED PROTECTION AGAINST RADIATION EMISSION, REPLACE ONLY WITH THESE TYPES OF SWITCHES. PRIMARY (INTERLOCK) SWITCH; SZM-V16-FA-63 or VP-533A-OF SECONDARY (INTERLOCK) SWITCH; SZM-V01-FA-33 (INTERLOCK) MONITOR SWITCH; SZM-V16-FA-62 or VP-532A-OF OVEN LAMP SWITCH; SZM-V6-FA-31 or VP-331A-OD LATCH The installation of PRIMARY, SECONDARY, MONI- TOR and OVEN LAMP SWITCH is as shown Fig. - Page 24 After the adjustment, make sure to perform the following test. This test should only be performed by authorized service personnel. (1) The in and out play of the door must be less than This (COM-NO) test should be performed with the 0.5mm when latched.
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Page 25: Interlock Continuity Test
INTERLOCK CONTINUITY TEST • The service personnel should replace all of the monitored safety interlock switches and monitor switch if the oven has been rendered inoperative due to the failure of the monitored safety interlock(s). • Be sure to connect the monitor switch after replacement and to check interlock/monitor continuity. COMPONENTS TEST PROCEDURE RESULTS... -
Page 26: Disassembly And Parts Replacement Procedure
DISASSEMBLY AND PARTS REPLACEMENT PROCEDURE CAUTION Before touching any oven component or wiring, first of all, disconnect the power supply cord and wait for about 5 minutes (in order to discharge the high voltage capacitor). A. REMOVING OUTER CASE (FIG. 14) (1) Remove four screws from the side section. - Page 27 D. REMOVING MAGNETRON (FIG. 17) E. REMOVING COOLING FAN MOTOR (FIG. 17) (1) Disconnect the wire leads from the magnetron terminals. (1) Remove the power supply cord from the oven (2) Remove the two screws holding the air duct to and disconnect lead wire from the Fuse magnetron.
- Page 28 G. REMOVING HIGH VOLTAGE TRANSFORMER (FIG. 18) H.V. TRANSFORMER (1) Disconnect the wire leads from the trans- former to the magnetron and H.V. Capacitor. H.V. CAPACITOR (2) Remove four screws securing the H.V. Trans- BRACKEY former to the base plate. H.V.
- Page 29 I. REMOVING CIRCULATION MOTOR K. REMOVING PRIMARY INTERLOCK (FIG. 22) SWITCH (FIG. 23) (1) Disconnect the wire leads from the circulation (1) After removing the complete control pane motor terminal. assembly, disconnect the wire leads from the (2) Remove the screws securing the supporter switches.
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Page 30: Troubleshooting
TROUBLESHOOTING CAUTION: 1. Check grounding before checking for other trouble. 2. Be careful of the high voltage circuit. 3. When checking the continuity of the switches or transformer, disconnect one lead wire from these parts and then check continuity without turning the power source on. 4. - Page 31 TEST PROCEDURE OR CONDITION CAUSE CORRECTION Oven light does not light with No power in home. Check wall outlet. door opened. Open wire in power cord or Replace or repair wiring. wire harness. Defective oven lamp switch or Test procedure oven lamp out of adjustment.
- Page 32 TEST PROCEDURE OR CONDITION CAUSE CORRECTION Defective membrane key of Test procedure membrane key No input can be programmed. P.C.B. of P.C.B. (See page 41.) Some inputs can not be Loose connection. Connect them tightly. programmed. Display shows a number or figure different from one touched.
- Page 33 TEST PROCEDURE OR CONDITION CAUSE CORRECTION MICROWAVE Oven does not go into a cook Primary and/or secondary Test procedure primary and cycle when Start pad is interlock switches defective or secondary switches. touched. out of adjustment. (See page 25.) Test procedure relay 1 of P.C.B. Defective relay 1 of P.C.B.
- Page 34 TEST PROCEDURE OR CONDITION CAUSE CORRECTION This is not a defect. No microwave oscillation. Child Lock is set. Touch “0” key pad till a beep sounds. (See page 14.) Test procedure relay 1 of P.C.B. Defective relay 1 of P.C.B. (See page 40.) Defective high voltage Test procedure high voltage...
- Page 35 TEST PROCEDURE OR CONDITION CAUSE CORRECTION CONVECTION CONV. indicator lights, but oven This is not a defect. Child Lock is set. does not go into cook cycle Touch “0” key pad till a beep when START pad is touched. sounds. (See page 14.) Test procedure relay 2 of Defective relay 2 of P.C.B.
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Page 36: Component Test Procedure
COMPONENT TEST PROCEDURE CAUTIONS 1. DISCONNECT THE POWER SUPPLY CORD FROM THE WALL OUTLET WHENEVER REMOVING THE OUT 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. -
Page 37: Test Procedure
COMPONENTS TEST PROCEDURE RESULTS ANTENNA GASKET CHASSIS FILAMENT Fig. 25 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. HIGH VOLTAGE Measure the resistance. Normal: Momentary indicates CAPACITOR (Ohm-meter scale: Rx1000) - Page 38 COMPONENTS TEST PROCEDURE RESULTS OVEN LAMP SWITCH Check for continuity of the switch Door Door (Wire leads removed.) with an Ohm-meter open close NOTE: After checking for the continuity of switches, make sure that they are correctly connected. FAN MOTOR Measure the resistance.
- Page 39 COMPONENTS TEST PROCEDURE RESULTS FUSE Check for continuity of the fuse Normal Abnormal with an Ohm-meter Fig. 33 NOTE: If the fuse is blown, check the primary, the secondary, and the monitor switches before replacing the fuse. (Refer to Test Procedure Switches on page 25.) If the fuse is blown by improper switch operation replace the defective switch and the fuse at the same time.
- Page 40 COMPONENTS TEST PROCEDURE RESULTS Relay 3 of P.C.B. Micro Power (Disconnect the 5 pin Cooking Start connector from P.C.B.) Fig. 37 Relay 4 of P.C.B. Convection (Disconnect the 5 pin Cooking Start connector from P.C.B.) Fig. 38 Relay 3 of P.C.B. Micro Power (Wire leads removed.) Cooking Start...
- Page 41 COMPONENTS TEST PROCEDURE RESULTS Membrane key Check continuity between switch MEMBRANE P C B terminals, by pressing an appropriate PANEL pad on the key board. The contacts assignment of the respective pads on the key board is as shown left figures. CONNECTOR KEY MATRIX AUTO HOLD...
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Page 42: Procedure For Measuring Microwave Energy Leakage
PROCEDURE FOR MEASURING MICROWAVE ENERGY LEAKAGE CAUTIONS MEASURING MICROWAVE ENERGY LEAKAGE • Be sure to check a microwave emission prior to servicing the oven if the oven is operative prior to • POUR 275 ± 15cc of 20 ± 5°C, 68 ± 9°F water in a servicing. -
Page 43: Measurement With A Fully Assembled Oven
MEASUREMENT WITH A FULLY DETERMINATION OF MEASUREMENT OF MICROWAVE POWER OUTPUT ASSEMBLED OVEN • Microwave power output measurement is made with • After all components, including the outer case are the microwave oven supplied at its rated voltage and fully assembled, measure for microwave energy operated at its maximum microwave power setting leakage around the door viewing window, the with a load of (1000 ±... -
Page 44: Exploded View And Parts List
#EV# EXPLODED VIEW AND PARTS LIST INTRODUCTION OVEN CAVITY PARTS OUT CASE PARTS BASE PLATE PARTS OVEN INTERIOR PARTS DOOR PARTS SWITHES PARTS CONTROL PANEL PARTS – 44 –... -
Page 45: Door Parts
#EV# 1 DOOR PARTS 13581A 15244U 13552A 15244H 15244T 13213A 14890A 14026U WPZ017 15244L 14510A 14026L 13720D 14970A WPZ017 – 45 –... -
Page 46: Control Panel Parts
#EV# 2 CONTROL PANEL PARTS 24781M 268711 WTP018 23572A 23790D 24510L 23506A 24970A 250201 – 46 –... -
Page 47: Oven Cavity Parts
#EV# 3. OVEN CAVITY PARTS WTT021 33112U WSZ137 34774U WTT010 WTT028 WTT011 34890C 33052M 34370T 35026C 36549S WTP013 53300C 35889A – 47 –... -
Page 48: Oven Interior Parts (1)
#EV# 4. OVEN INTERIOR PARTS (1) WSZ002 56411A WTT021 WTP015 50FZZA WTT011 53551S 56549F 56201A WMT001 34930W WTP002 54370D 54974S 55900A 56930M 54810U 56420A WTT021 WTP004 54932A WSZ137 WSZ137 56324A 55262A 368771 – 48 –... -
Page 49: Oven Interior Parts (2)
#EV# 5. OVEN INTERIOR PARTS (2) 56912B 36549C WNH002 WTT010 54810S WTP004 WTT021 WTT043 WTT010 56930G 53550L 55900N 53504A WTT021 33741A WTT021 56208A 35264A 35012T 54975G 34990A 34810Q WMT002 WTT022 35301A 343501 55900C WWP008 WNH003 WWS005 WTT010 568773 35012R – 49 –... -
Page 50: Latch Parts
#EV# 6. SWITCHES PARTS 43501U 43500U 466004 WSZ085 WTP007 466001 466002 WSZ085 WTP010 466003 WTP007 43501L 43500L 44510A 44360A – 50 –... -
Page 51: Base Plate Parts
#EV# 7. BASE PLATE PARTS WSZ137 WSZ002 56170D 54810C 56851D 63303A 50CZZH 56851C 34774L 63302A WSZ153 647781 13806F WTT021 647781 WTT028 – 51 –... -
Page 52: Wiring Harness Parts
#EV# 8. WIRING HARNESS PARTS 568771 568772 – 52 –... -
Page 53: Circuit Board
9. CIRCUIT BOARD – 53 –... -
Page 54: Circuit Board Schematic Diagram
10. CIRCUIT BOARD SCHEMATIC DIAGRAM – 54 –...