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Internal Use Only
Website http://biz.lgservice.com
MICROWAVE OVEN
SERVICE MANUAL
MODEL: MS3447GR
MS3447GRS
CAUTION
BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
July, 2007
Printed in Korea
P/NO : MFL31039007
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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
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CONTENTS (Page) SAFETY PRECAUTIONS ---------------------------------------------------------------------- Inside front cover SPECIFICATIONS ----------------------------------------------------------------------------------------------------- 1-1 CAUTIONS --------------------------------------------------------------------------------------------------------------- 2-1 INSTALLATION -------------------------------------------------------------------------------------------------------- 3-1 OPERAT
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SPECIFICATIONS ITEM DESCRIPTION MODEL MS3447GR / MS3447GRS Power Requiremen 230/240 Volts AC 50 Hz 1600 Watts Single phase, 3 wire grounded Power Output 1100 Watts full microwave power (IEC60705) Microwave Frequency 2450 MHz Magnetron 2M246-050GF Timer 0 ~ 99 min. 99 sec. Outside Dimensions 556mm (W) x 320mm (H) x 438mm (D) Cavity Dimensions 374mm (W) x 254mm (H) x 406mm (D) 16.5 kg (approx.) Net Weight 17.9 kg (approx.) Shipping weight Control Complement Touch Control System Clock : 1:00 - 12:
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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. • DO NOT operate on a 2-wire extension cord during All input and output microwave connections, repair and use. waveguide,
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INSTALLATION 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. misaligned door, damage around the door or dents It is imperative, therefore, to make sure it is properly inside the cavity or on the exterior. earthed before servicing 2. Put the oven on a counter, table, o
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OPERATING INSTRUCTIONS FEATURES CONTROL PANEL 1. SENSOR REHEAT. 2. SENSOR COOK. 3. AUTO COOK: Used to select the auto cook 1 4. AUTO REHEAT: Used to select the auto reheat. 5. AUTO DEFROST: This feature provides you with the best defrosting method for frozen foods. 6. MORE / LESS: All of the one touch cook and TIMED COOK 2 can be adjusted to cook food for a longer or shorter time. MORE Pressing MORE will add 10 seconds to the cooking time. 34 LESS Pressing LESS will subtract 10 seconds of cook
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OPERATING SEQUENCE The following is a description of component functions 6. CHILD LOCK during oven operation. This oven has a CHILD LOCK feature TO SET CHILD LOCK 1. CANCEL FUNCTION • Touch STOP/CLEAR pad Touch the STOP/CLEAR pad whenever you need to • Touch and hold STOP/CLEAR pad LOCKED cancel an entry or a function currently in use. appears on the display. The display will return either to the last item entered or to the clock. TO CANCEL CHILD LOCK • Touch and hold STO
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SCHEMATIC DIAGRAM LGE Internal Use Only Copyright © 2007 LG Electronics. Inc. All right reserved. 4-3 Only for training and service purposes
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CIRCUIT DESCRIPTION • A high voltage of approximately 2100 volts AC is GENERAL DETAILS generated in the secondary of the high voltage • The low voltage transformer supplies the necessary transformer which is increased by the action of the high voltage to the micom controller when power cord is voltage diode and charging of the high voltage plugged in. capacitor. • When the door is closed, the primary switch is ON, the • The negative 4000 Volts DC is applied to the filament secondary switch is ON
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SERVICE INFORMATION TOOLS AND MEASURING INSTRUMENTS NECESSARY TOOLS NECESSARY MEASURING INSTRUMENTS Tools normally used for TV servicing are sufficient. • TESTER (VOLTS-DC, AC, Ohmmeter) Standard tools are listed below. • Microwave survey meter • Diagonal pliers - Holaday HI-1500 • Long nose pliers HI-1501 • Phillips screwdriver - Narda 8100 • Flat blade screwdriver 8200 • Wrench (size 5mm) • Inch scale • Nutdriver (size 5mm) • 600 cc non conductive material beaker (glass or plastic), 1 • Adjust
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MEASUREMENT WITH OUTER CASE NOTES WHEN MEASURING REMOVED • Do not exceed meter full scale deflection. • The test probe must be moved no faster than • When you replace the magnetron, measure for 1 inch/sec (2.5 cm/sec) along the shaded area, microwave energy leakage before the outer case is otherwise a false reading may result. installed and after all necessary components are • The test probe must be held by the grip portion of the replaced or adjusted. handle. Special care should be taken in mea
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MEASUREMENT OF MICROWAVE POWER OUTPUT • Microwave power output measurement is made with • The microwave power output P in watts is calculated the microwave oven supplied at its rated voltage and from the following formula : operated at its maximum microwave power setting with 4187 x (∆ T) + 0.55 X (T2 - T0 ) X M P = a load of (1000±5) g of potable water. T • The water is contained in a cylindrical borosilicate glass • T2: Temperature after heating vessel having a maximum material thickness of 3
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Remove choke cover 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 PCB SUB ASS ’Y to the control panel. 3) Disconnect the flat cable from the PCB SUB ASS’Y and take off the PCB SUB ASS ’Y Remove door assembly 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
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F. AIR DUCT ASSEMBLY REMOVAL H. REMOVING THE TURNTABLE MOTOR 1) Disconnect the leadwire from the lamp. 1) Remove the turntable and rotating ring. 2) Remove the mounting screw to the magnetron. 2) Lay the unit down on its back. 3) Remove the turntable motor cover. The turntable base cover is easily removed by G. MAGNETRON REMOVAL pinching the eight parts with a wire cutting. 1) Disconnect the lead wire from the magnetron. 4) Disconnect the leadwire from the turntable motor 2) Carefully remove the
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I. HIGH VOLTAGE TRANSFORMER L. INTERLOCK SYSTEM REMOVAL 1) INTERLOCK MECHANISM The door lock mechanism is a device which has 1) Discharge the high voltage capacitor. been specially designed to eliminate completely 2) Disconnect the lead wire from magnetron, high voltage microwave activity when the door is opened during transformer, and capacitor. cooking and thus to prevent the danger resulting 3) Remove the screw holding the high voltage from the microwave leakage. transformer to the baseplate
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INTERLOCK CONTINUITY TEST 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-62 OR VP-532A-OF FOR MONITOR SWITCH TYPE NO.SZM-V 16-FA-63 OR VP-533A-OF FOR SECONDARY SWITCH A. PRIMARY INTERLOCK SWITCH TEST B. SECONDARY INTERLOCK SWITCH TEST When the door release button is depressed slowly Disconnect the wire lead from the secondary with the door closed, a
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COMPONENT TEST PROCEDURE 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 remo
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COMPONENTS TEST PROCEDURE RESULTS Antenna Gasket Chassis Filament 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: Momentarily indicates CAPACITOR (Ohm-meter scale: Rx1000) several ohms, and • Terminal to terminal. then gradually returns to infinite. Normal: Infinite. Measure the resistance. (Ohm-meter scale: Rx1000) • Terminal to case. HIGH VOLTAGE Meas
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COMPONENTS TEST PROCEDURE RESULTS RELAY 2 Check for continuity of relay 2 with an POWER ohm-meter. LEVEL (Remove wire leads from relay 2 and operate the unit.) 1 4 sec 18 sec 2 6 sec 16 sec 3 8 sec 14 sec 4 10 sec 12 sec 5 12 sec 10 sec 6 14 sec 8 sec 7 16 sec 6 sec 8 18 sec 4 sec 9 20 sec 2 sec 10 22 sec 0 sec Relay 2 Measure the resistance. Normal: FAN MOTOR (Ohm-meter scale: R x 1) A: Approx. 85 ~ 100 ohm (Wire leads removed) B: Approx. 10 ~ 25 ohm Abnormal: Infinite or several ohm. B A Meas
