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MICROWAVE OVEN SERVICE MANUAL

1. 5 1 TOOLS AND MEASURING INSTRUMENTS caros 5 1 MICROWAVE LEAKAGE TEST 5 1 MEASUREMENT OF MICROWAVE POWER OUTPUT nnne 5 3 DISASSEMBLY AND ADJUSTMENT 5 3 INTERLOCK CONTINUITY 6 5 7 COMPONENT TEST PROCEDURE 5 8 TROUBLE SHOOTING REED 5 12 EXPLODED VIEW Ssistsicteddncddinccccncdociscacdaccanacsaccsondinndantdsasesaddiacdsancievadaddsavesatd ncantens 6 1 REPLACEMENT PARTS LIST 55 Non Rois 7 1 LGE Internal Use Only Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes SPECIFICATIONS ITEM DESCRIPTION MODEL MH 6387 AR Power Requirement 230 Volts AC 50 Hz Single phase 3 wire grounded Microwave 1250W Grill 1000W Combi 2200W Power Output 850 Watts full microwave power IEC60705 Microwave Frequency 2450 MHz Magnetron 2M167B M47J1 Timer 0 99 Min Outside Dimensions 507 W x 283 H x 435 D mm Cavity Dimensions Net Weight 331 W x 203 H x 360 D mm 14 5 kg approx Shipping weight 16 5 kg approx Control Complement Microwave Power for
2. Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes 4 3 SCHEMATIC DIAGRAM He 1 qvos LINDYID IOHLNOO ANY MOLIOVdVO A H oa JN B VEN 10 paa 0000 4 Ssngan 107 Pt FEE MM 38 Ta ty 811 S 1 Nd NO 0 9 HOLIMS AYVONO93S g HM 7 IWLSOWYSHL dy que 18 WES qn A EET IM IN n T me QD Yala 3SION qu 1 1 1 ME i ov a s 0 ADA a 1 1 1 1 foro tacto HM ivan 9 3 M ya YAINYOASNVYL 3 H9IH dy HOLIMS LGE Internal Use Only CIRCUIT DESCRIPTION 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 e Each indicator light turns on to indicate
3. CONDITION CHECK RESULT CAUSE REMEDY No microwave Disconnect the No continuit Defective P C B Replace P C B oscillation gt wire leads from assembly assembly relay 2 and check continuity of relay2 gt Continuity Operate the unit Check H V gt Abnormal Defective high Replace high transformer voltage voltage transformer transformer normal Check H V Abnormal Defective high Replace high capacitor voltage capacitor voltage capacitor normal Check H V Defective high Replace high diode pisano voltage Diode voltage Diode gt normal Check ABO Defective Replace Magnetron magnetron magnetron 5 16 Only for training and service purposes LGE Internal Use Only Operates properly on HIGH TROUBLE 6 Oven does not cook properly when programmed for the set power level CONDITION CHECK RESULT CAUSE REMEDY Output is full when Disconnect the Abnormal Defective P C B Replace P C B you set lower wire leads from assembly assembly power level relay 2 and check continuity relay 2 Operate the unit TROUBLE 7 Grill CONDITION CHECK RESULT CAUSE REMEDY 1 Heater is not Heater Abnormal Malfunction the Replace operating heater Normal Thermostat and Malfunctio
4. Segment missing Partial segment missing Digit flickering NOTE Slight flickering is normal Colon does not turn on or blink A distinct change in the brightness of one or more numbers in display One or more digits in the display are not lighting Display indicates a number different from one touched for example key in 5 and 3 appears in the display Specific numbers for example 7 or 9 will not display when key pad is touched Display does not count down with time blinking or up with clock operation Display obviously jumps in time while counting down Display counts down too fast while cooking Each indicator light does not turn on after setting cooking cycle Display time of day does not reappear when cooking is finished Beep sound is not heard when correct key is touched different from one touched 4 Random programming when touching other pads 5 Display is fixed at some figure and can not accept any input LGE Internal Use Only 5 13 CONDITION CHECK RESULT CAUSE REMEDY 1 No input can be Check the conn Colin Defective PCB Replace PCB programmed ection between d assembly assembly membrane key assembly and T Loose onnect them PCB assembly connection tightly 2 Some
5. 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 SWITCH 4 TRANS 5 FORMER REA d SECONDARY SWITCH MICOMCONTROLLER 0 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 GRILL THERMOSTAT E GRILL HEATER RELAY 3 Turntable rotates 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 LGE Internal Use Only SERVICE INFORMATION TOOLS AND MEASURING
6. Y 7 After repairing the motor rotate the removed turntable motor cover NOTE 8 Fit the turntable motor cover s projecting part to the base plate slit 9 The taptite screw shall be used when a turntable motor cover is secured with a screw 1 Disconnect the leadwire from the high voltage transformer and high voltage capacitor 2 Carefully remove the mounting screws holding the magnetron and the waveguide 3 Remove the magnetron ASS Y until the tube is clear from the waveguide 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 1R the wire lead f the turntabl t be sure that the gasket is in good condition VERY CABE 3 After replacing the magnetron check for microwave 2B t th t tthe wi h leakage with a survey meter around the i magnetron Microwave energy must be below the limit of 5 mW crr 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 Waveguide Dome Waveguide Bracket Magnetron Gasket Magnetron Turntable Motor LGE Internal Use Only 5 5 Copyright O 2007 LG Ele
7. 5 1 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 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 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 bcm 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 Kem CNN NU NUNC Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes 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 com
8. Inc All right reserv pu Copyright O 2007 LG Electro Only for train rposes ing and service EV OVEN CAVITY PARTS gt 4980W1A058B Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes 6 4 LGE Internal Use Only EV LATCH BOARD PARTS Ca EB Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes EN 6 5 LGE Internal Use Only EV INTERIOR PARTS Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes 6 6 LGE Internal Use Only BASE PLATE PARTS LGE Internal Use Only 6 7 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes LG Electronics Inc
9. Variable Cooking Power level Full power throughout the cooking time MED HIGH approx 80 of Full power MEDIUM approx 6096 of Full power DEFROST LOW WARM approx 4096 of Full power approx 2096 of Full power Rating Label Location Back Side Accessories Owner s manual Glass tray Rotating ring High rack Low rack This microwave oven is designed for household use only It is not recommended for commercial purposes Copyright O 2007 LG Electronics Inc All right reserved 1 1 Only for training and service purposes LGE Internal Use Only 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 i D 4 MEN Remove your watches whenever working close to or replacing the Magnetron NEVER operate the oven with no load NEVER injure the door seal and front plate of the oven c
10. inputs Replace key Everything works Defective key Replace key cannot be membrane as specified membrane membrane programmed assembly and assembly assembly check operation 3 Display shows Replace PCB number or figure Sill nave trouble connection assembly Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes TROUBLE 2 Oven does not operate at all Display window does not display any figures and no input is accepted CONDITION CHECK RESULT CAUSE REMEDY Check continuit AE Malfunction of the Replace primar 1 Fuse blows He heck con inullY X Continuity y of monitor monitor switch and monitor switch with switches door closed gt No continuity 2 1 Replace fuse Check continuity x Continuity Shorted contact at gt Replace primary e or primary the primary switch and monitor switch with switches door opened No continuity Disconnect one Ciim Defective high Replace high side of the wire voltage capacitor voltage capacitor lead connected from transformer Defective high volt Replace high volt Fuse blows again gt o to the high age transformer age transformer voltage capacitor and operate the unit NOTE All th
11. 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 PRIMARY FUSE SWITCH E O 7 MONITOR S BAN 7 SWITCH FORMER O O SECONDARY RELAY 2 92 SWITCH 00 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 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes
12. 4 5 microwave cooking E 7 GRILL Used to select the grill cooking 8 f 8 COMBI Used to select the combination cooking 8 _ 9 9 9 CLOCK Used to set the time of day F38 10 DIAL To select convection temperature change cooking time and weight D 11 QUICK START To quickly set the cooking time directly 12 CLEAR Used to clear all entries except time of day 11 221 12 LGE Internal Use Only 4 1 Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes OPERATING SEQUENCE The following is a description of component functions during oven operation 1 SETTING THE CLOCK 7 COMBI COOKING Clear Combi gt Time m Quick Start Clear gt Clock gt Setthe hour gt Clock 8 AUTO WEIGHT DEFROST Setthe Clock minutes NOTE 1 You can set 12 hour clock or 24 hour clock optionally 2 Clock will operate as long as power is applied to the oven 2 CANCEL FUNCTION Touch the Clear 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 3 CHILD LOCK This oven has a CHILD LOCK feature TO SET CHILD LOCK e Touch the Clear pad e Touch Clear pad appear in the display TO CANCEL CHILD LOCK e
13. E LEADS ARE IN THE CORRECT POSITION WHEN REMOVING THE WIRE LEADS FROM THE PARTS BE SURE TO GRASP THE CONNECTOR NOT THE WIRES LGE Internal Use Only 5 11 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes 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 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 5 Do not touch any part of the circuitry on the digital programmer circuit since static electric discharge may damage this control panel Always touch yourself ground while working on this panel to discharge any static charge built up in your body CONDITION CAUSE REMEDY Microwave oven gt Inserting many plug into one gt Avoid using ot
14. 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 e 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 cm 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 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 4 mW cm Always start measuring of an unknown field to assure safety for operating personnel from radiation leakage LGE Internal Use Only
15. No continuity Defective oven lamp Replace oven lamp gt S Normal TROUBLE 4 Oven seems to be operation but little heat is produced in oven load CONDITION CHECK RESULT CAUSE REMEDY Output is low Check the Lower than 90 of Decrease in Suggest customer power source rating voltage Source voltage contact local voltage with load electric power Le Normal utility co or qualified electrician Disconnect the gt wire leads from Abnormal Defective P C B Replace P C B C O relay 2 and check assembly assembly on and off time with multitester gt Abnormal Measure the Abnormal Defective Replace Abnormal output magnetron magnetron NOTE Simple test of power output conducted by heating one liter water for one min if available LGE Internal Use Only 5 15 Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes TROUBLE 5 No microwave oscillation even though oven lamp and fan motor run Display operates properly Copyright O 2007 LG Electronics Inc All right reserved
16. SCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE SERVICING refer to page 2 1 LGE Internal Use Only 5 3 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes D DOOR GROSS ASSEMBLY REMOVAL 1 Open the door 2 Remove the choke cover cap 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 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 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 Remove Hinge Plate Remove Door Assembly Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes E 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 voltag
17. Touch the Clear e Touch Clear pad L disappears 4 QUICK START Clear m Quick start 5 MICROWAVE COOKING Auto Weight Clear 3 Defrost kg m Quick Start 9 AUTO COOK Auto Weight Clear Cook kg Quick Start Clear Power Quick Start 6 GRILL COOKING Clear 3 Grill Time gt Quick Start Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes LGE Internal Use Only WLL Wa ANTE 10 aL i punoJB sisseuo y jo jeuruuJe NO ya yy ayy Bunioys Aq Jonoedeo MOTISA 034 qu ora A ay ebreuosiq ONIOIANAS 93303398 ies D CS 39v L 10A Ln VH lt 13 H3193NNOO3G 3f10INHO3 L NOLLNIAY3LNI LNVAV 3O9LLON LNOHLIM esse A 01 LOargNS 39 6 a 2 JOA JoyesuepuoxsBunuuedsuoou SN YLHOV H3N3dO SI HOOQ I ILON HOLIMS YOLINOW
18. URE RESULTS 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 CAPACITOR Measure the resistance Normal Momentarily indicates Ohm meter scale Rx1000 several ohms and then Terminal to terminal gradually returns to infinite Measure the resistance Normal Ohm meter scale Rx1000 Terminal to case HIGH VOLTAGE DIODE NOTE Some inexpensive meters may indicate infinite resistance in both direction LGE Internal Use Only Measure the continuity Forward Normal Continuity Ohm meter scale Rx10000 Abnormal Measure the continuity Reverse Normal Ohm meter scale Rx10000 Abnormal Continuity 5 9 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes COMPONENTS TEST PROCEDURE RESULTS FUSE Check for continuity of the fuse with an Normal Abnormal 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 H V FUSE Check for continuity of the H V Fuse with Abnormal multi meter Y HEATER ELEMENT Measure t
19. avity NEVER put iron tools on the magnetron NEVER put anything into the latch hole and the interlock switches area LGE Internal Use Only 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 COOLING FIN FILAMENT TERMINALS MAGNETRON CHASSIS GROUND MAGNETRON THE OVEN IS TO BE SERVICED ONLY BY PROPERLY QUALIFIED SERVICE PERSONNEL Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes 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 eart
20. ctronics Inc All right reserved Only for training and service purposes K 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 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes 5 6 L 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 ADJUSTMENT DIRECTION PRIMARY SWITCH 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 les than 0 5 mm 1 64 inch Don t push the door release button while making adjustment Make sure that t
21. dded 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 AT of 10 2 K is measured where T is the time 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 in seconds and AT is the temperature rise The initial heat and final water temperatures are selected so that the maximum difference between the final water WATER LOAD temperature and the ambient temperature is 5 K ep SSE TURNTABLE A OUTER CASE REMOVAL C CONTROL PANEL ASSEMBLY 1 Disconnect the leadwire from the PCB SUB ASS Y 1 Disconnect the power supply cord from the outlet 2 Remove the screws for the earth and securing the 2 Remove the screws from the rear and along side control panel edges of the case 3 Lift control panel ASS Y from the oven by the tab The outer case must be moved backward to be lifted unhooked off B POWER SUPPLY CORD 1 Remove the outer case 2 Disconnect two terminals and remove one screw of the earth terminal CAUTION DI
22. e transformer to the baseplate F FAN MOTOR ASSEMBLY REMOVAL 1 Discharge the high voltage capacitor 2 Disconnect the leadwire from fan motor noise filter and high voltage capacitor 3 Remove the two screws holding the the suction guide ASS Y to the oven cavity and remove the high voltage diode earth screw 4 Remove the screw of the capacitor bracket 5 Remove the two screws holding the fan motor ASS Y to the suction guide ASS Y G HIGH VOLTAGE CAPACITOR AND DIODE REMOVAL 1 Discharge the high voltage capacitor 2 Disconnect the leadwire from fan motor noise filter and high voltage capacitor 3 Remove the screw holding the suction guide ASS Y to the oven cavity and remove the high voltage diode earth screw 4 Remove the screw holding the high voltage capacitor bracket Fan Motor ASS Y A GU 22 gt sH V 22 Transformer H V Diode LGE Internal Use Only H AIR DUCT ASSEMBLY REMOVAL J REMOVING THE TURNTABLE MOTOR 1 Disconnect the leadwire from lamp 1 Remove the turntable 2 Remove the mounting screw to Latch Board 2 Remove the Rotating Ring 3 Lay the unit down on its back 4 Remove the turntable motor cover I MAGNETRON REMOVAL The turntable base cover is easily removed by pinching the six parts with a wire cutting 5 Disconnect the leadwire from the turntable motor terminals 6 Remove the screw securing the turntable motor to the oven cavity ASS
23. e microwave oven as far away as possible connected to the terminal in the plug which is marked from TV RADIO COMPUTER etc to prevent with the letter E or by the earth symbol 4 or interference colored green or green and yellow 8 Do not touch the front glass during or after cooking of the Grill and Combination mode This glass is very hot during heater operating The wire which is colored blue must be connected to the terminal in the plug which is marked with the letter N or colored black 9 Do not operate the oven at microwave and combination mode with Grill rack placed in the The wire which is colored brown must be connected cavity when the oven is empty to the terminal in the plug which is marked with the 10cm letter L or colored red Copyright O 2007 LG Electronics Inc All right reserved 3 1 LGE Internal Use Only Only for training and service purposes OPERATING INSTRUCTIONS FEATURES Oven Front Plate Window Door Screen Door Seal HIGH RACK Cp LOW RACK ROTATING RING CONTROL PANEL N 1 DISPLAY WINDOW Used to show time of day power level of cooking cooking category 2 EUROPEAN COOK Used to select the european AUTO COOK Used to select the auto cook 3 2 4 AUTO DEFROST To select auto defrost 2 1 8 4 3 5 QUICK DEFROST Used to defrost quickly n 6 MICRO Used to select the power level for
24. ese switches must be replaced at the same time Refer to page 5 6 5 7 2 Fuse does not blow Check continuity Defective mag Replace mag of magnetron netron thermostat netron thermostat thermostat Continuity Check continuity No continuity of power supply cord Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes 5 14 Defective power supply cord supply cord LGE Internal Use Only TROUBLE 3 Display shows all figures set but oven does not start cooking while desired program times are set and START pad is touched CONDITION CHECK RESULT CAUSE REMEDY 1 Setting time does Check continuity continuity gt Defective Replace not count down of secondary secondary switch secondary switch when touching switch with START pad door closed gt Continuity 2 Fan motor or oven lamp do not turn on Check continuity of secondary No continuity Defective P C B Replace P C B switch with assembly gt assembly door closed Continuity gt Loose connection gt a then Check fan motor gt No continuity Defective fan gt Replace fan motor motor Check oven lamp
25. for the continuity of switches make sure that are connected correctly Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes 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 removed FILAMENT WINDING TERMINAL SECONDARY TERMINAL PRIMARY TERMINAL 1 Measure the resistance Ohm meter scale Rx1 and Rx100 Primary winding Approx 2 5 Q e Secondary winding Approx 110 Q Filament winding Less than 0 4 Q Measure the resistance Ohm meter scale Rx1000 Primary winding to ground Normal ee Filament winding to ground Normal ee MAGNETRON Wire leads removed Measure the resistance Ohm meter scale Rx1 Normal Less than 1 O Filament terminal Measure the resistance Ohm meter scale Rx1000 Normal Filament to chassis Copyright O 2007 LG Electronics Inc All right reserved 5 8 LGE Internal Use Only Only for training and service purposes COMPONENTS TEST PROCED
26. he 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 CAUTION CHECK THE CORRECT POSITION MAGNETRON FIG 1 H V TRANSFORMER bid CIRCUIT PROTECTOR PRIMARY LGE Internal Use Only 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 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 cl
27. he resistance Normal Wire leads removed Multi meter scale Rx1 Grill heater Approx 38 ohm at 20 30 C Measure the resistance with 500V 100M ohm Normal more than 0 5 Mohm insulation resistance meter NOTE Make sure heater is fully cooled when tested 0 C Approx 90 C Approx 90 C GRILL THERMOSTAT OVEN THERMOSTAT MAGNETRON THERMOSTAT 0 C Approx 145 C Approx 145 C Copyright 2007 LG Electronics Inc All right reserved 5 10 LGE Internal Use Only Only for training and service purposes COMPONENTS TEST PROCEDURE RESULTS Disconnect the 8 pin connector from P C B Refer to schemetic diagram Check for P C B connector Cooking Start pa RELAY 2 RELAY 3 OF P C B Wire leads removed Note Relay Relay 1 Fan motor Turntable motor Oven lamp Relay 2 Microwave Relay 3 Grill Relay 2 Cooking Start Dames FAN MOTOR Wire leads removed Measure the resistance Ohm meter scale R x 1 Normal A B A C 40 600 300 500 Q Abnormal ee or several 2 TURNTABLE MOTOR Wire leads removed Measure the resistance Ohm meter scale R x 1000 Normal Approx 100 200 Abnormal or several Q NOTE A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON MAKE SURE THE WIR
28. hed 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 or shelf that is strong enough to hold the oven and the food and WARNING utensils you put in it The control panel side of the THIS APPLIANCE oven is the heavy side Use care when handling MUST BE EARTHED 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 IMPORTANT Make sure the microwave oven legs are in place to ensure proper air flow The wires in this mains lead are colored in accordance with the following code 4 The oven should not be installed in any area where heat and steam are generated because they may Green and yellow Earth damage the electronic or mechanical parts of the Blue Neutral unit Brown Live Do not install the oven next to a conventional surface unit or above a conventional wall oven As the colors of the wires in the mains lead of this 5 Use microwave oven in an ambient temperature appliance may not correspond with the colored less than 104 F 40 C markings identifying the terminals in your plug proceed as follows 6 Place the microwave oven on a sturdy and flat surface at least 10 cm 4 inches from the wall The wire which is colored green and yellow must be 7 Place th
29. her electrical does not work plug outlet and using appliances when you use the them at the same time microwave oven causes overloading Microwave oven plug is not Insert microwave oven plug inserted tightly securely Output power is too low Low AC input voltage gt Use the microwave oven at adequate line voltage Food temperature is too low This may not be a defect It is possible that the food should be cooked for a longer time period Sparks occurring Using metallic ware and Do not use metallic ware for allowing it to touch the oven cooking except where noted wall in the cooking guide Ceramic ware trimmed in Do not use any type of gold or silver powder is used cookware with metallic trimming Uneven cooking m gt Inconsistent intensity of gt 1 Wrap the thinner part with microwave by their aluminum foil characteristics 2 Use plastic wrap or lid 3 Stir once or twice while cooking soup cocoa or milk etc Turntable drags or makes gt _ Distribute food evenly Cook IExcessive weight on tray or noise propery balanced smaller portions and or use propery lighter weight cookware Copyright O 2007 LG Electronics Inc All right reserved 5 12 LGE Internal Use Only Only for training and service purposes TROUBLE 1 Oven lamp does not turn on when the timer knob is pushed with door closed 1 Incomplete segments
30. n the relay3 Grill abnormal thermostat Normal Wire connection gt No continuity Open or loosen connect tightly 1 Lower tempera Heater Abnormal Malfunction the Replace ture the oven heater Normal Thermostat and Abnormal Malfunction the Replace relay3 Grill thermostat NOTE Make sure the wore leads correct position When removing the wire leads from parts be sure to grasp the connector not the wires When removing the magnetron be sure to install the magnetron gasket in the correct position and in good condition LGE Internal Use Only 5 17 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes EV EXPLODED VIEW INTRODUCTION MODEL MH 6387AR OVEN CAVITY PARTS DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS Copyright 2007 LG Electronics Inc All right reserved 6 1 LGE Internal Use Only Only for training and service purposes EV DOOR PARTS LGE Internal Use Only 6 2 Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes CONTROL PANEL PARTS LGE Internal Use Only 6 3 ed nics
31. osed circuit When the primary switch operation is abnormal make the necessary adjustment or replace the switch only with the same type of switch COMPONENTS TEST PROCEDURE 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 RESULTS LGE SWITCHES Wire leads removed Check for continuity of the switch with an Ohm meter Door Door open close Primary Switch 3 ua Monitor Switch Secondary Switch Go Internal Use Only NOTE After checking
32. ponents are replaced or adjusted Special care should be taken in measuring the following parts Circled area of below Fig Around the magnetron The waveguide WARNING AVOID CONTACTING ANY HIGH VOLTAGE PARTS Magnetron H V Transformer H V Capacitor H V Cable Ass y H V Circuit Protector 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 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes 5 2 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 thi
33. rg Website http biz lgservice com LG MICROWAVE OVEN MODEL MH 6387AR CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL August 2007 P NO MFL32188507 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
34. s 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 LGE Internal Use Only 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 AT 0 55 X Tz To XM a load of 1000 5 g of potable water P The water is contained in a cylindrical borosilicate glass T vessel having a maximum material thickness of 3 mm e Temperature after heating and an outside diameter of approximately 190 mm Temperature after bown The oven and the empty vessel are at ambient Weight of bowl temperature prior to the start of the test initial temperature T1 of the water is 10 2 C It is measured immediately before the water is a
35. 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 ENERCY Copyright O 2007 LG Electronics Inc All right reserved LGE Internal Use Only Only for training and service purposes CONTENTS Page SAFETY qs utes e quales du Inside front cover SPECIFICATIONS 1 1 CAUTIONS Sinai rea 2 1 INSTALLATIONS 3 1 OPERATING INSTRUCTIONS 4 1 MH 4 1 CONTROL PANEL ERES 4 1 OPERATING SEQUENCE enne tennte tenetis 4 2 SCHEMATIC DIAGRAM 4 3 CIRCUIT DESCRIPTION 4 4 SERVICE INFORMATION eeeeeeeeeeeeeeeee rere

MICROWAVE OVEN SERVICE MANUAL

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