MICROWAVE OVEN SERVICE MANUAL
Contents
1. OVEN THERMAL PRIMARY BN CUT OUT SWITCH BN BN o RD BK H V TRANSFORMER RO BK e esee ceni gt YL ce o BN 5 c amp C lt x H V CIRCUIT PROTECTOR x B SE A i MONITOR o 5 switcH PREDSE 2 300 E ANS N a t E 5 5 A lt gt CAPCITOR ES FA fey O E CM ee SIE E GAl 1 o HO o 1 A eL WH LI 8L BL Lp o 4 2 gt MAGNETRON SECONDARY w e TO 81817119 eH 1 3 5 7 9 1112 v 97 NOTE DOOR IS OPENED 0 9 e De D 1 3 3 3 BN BROWN BL BLUE YL YELLOW S o 32 3 RD RED WH WHITE PK PINK TRANS THERMISTOR BK BLACK ACHTUNG Hochspannungskondesator vor allen Servicearbeiten gegen Masse entladen AVANT INTERVENTION TECHNIQUE DECONNECTER ET DECHARGER LA CAPACITE DE HAUT VOLTAGE BEFORE SERVICNG Discharge the high voitage Capacitor by shorting the negative high voltage Terminal of it to chassis ground G Y GREEN AND YELLOW STRIPED F M FAN MOTOR O L OVEN LAMP T T M TURN TABLE MOTOR C M CIRCULATION MOTOR Copyright 2007 LG Electronics Inc All right reserved Only for training an2. Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes 6 2 LGE Internal Use Only CONTROL PANEL PARTS LGE Internal Use Only 6 3 ed nics Inc All right reserv pu Copyright 2007 LG Electro rposes Only for training and service EV OVEN CAVITY PARTS o 1 021 952640 948501 OT gt ee See Se LGE Internal Use Only 6 4 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes LATCH BOARD PARTS LGE Internal Use Only 6 5 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes EV INTERIOR PARTS Button Head Torx style 2 m LGE Internal Use Only 6 6 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes EV BASE PLATE PARTS LGE Internal Use Only 6 7 Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes LG Electronics Inc
3. 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 the same time Replace just the fuse if the switches operate normally HEATER ELEMENT Wire leads removed Measure the resistance Normal Multi meter scale Rx1 Grill heater Approx 42 ohm at 20 30 Approx 63 ohm at 20 30 Convection heater Measure the resistance with 500V 100M ohm insulation resistance meter Normal more than 0 5 Mohm NOTE Make sure heater is fully cooled when tested MAGNETRON THERMOSTAT 0 C Approx 60 C Approx 60 C C 0 C Approx 145 C Copyright 2007 LG Electronics Inc All right reserved 5 10 Only for training and service purposes LGE Internal Use Only COMPONENTS TEST PROCEDURE RESULTS Cooking Start OFF Disconnect the 9 pin Check for P C B connector connector from P C B Refer to schemetic diagram 1234567809 N La pam RELAY 2 RELAY 3 RELAY 5 Cooking Start OF P C B Wire leads removed Relay 2 Relay 2 Microwave Relay 3 Grill Relay 5 Convection o Relay 3 MOTOR Measure the resistance Normal Approx 300 500 ohm Wire leads removed Ohm meter scale R x 1 Abnormal Infinite or se
4. Website http biz lgservice com LG MICROWAVE OVEN MODEL MC 3089NBC CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL March 2008 P NO MFL34215509 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 t
5. Wire leads removed with a Multi meter Check for continuity of the switch Door Door open close Primary Switch Monitor Switch Secondary Switch LGE Internal Use Only NOTE After checking for the continuity of switches make sure that are correctly connected Copyright O 2007 LG Electronics Inc 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 SECONDARY WINDING TERMINAL TERMINAL PRIMARY TERMINAL Measure the resistance Ohm meter scale Rx1 and Rx100 Primary winding Approx 2 0 ohm e Secondary winding Approx 150 ohm Filament winding Less than 1 ohm Measure the resistance Ohm meter scale Rx1000 Primary winding to ground Normal Infinite Filament winding to ground Normal Infinite MAGNETRON Wire leads removed Measure the re
6. 7 SPEED HOT AIR To pre heat Stop Clear Select Speed hot air Desired convection temp 100 C 250 C To cook Stop Clear Select Speed hot air Start Desired convection temp 100 250 gt Press Dial 8 EZ CLEAN Desired cooking time Start Stop Clear m Select ez clean Start 9 AUTO DEFROST Stop Clear Function Auto Defrost __ Desired defrost category gt Press Dial y Food weight gt Start 10 LARGE CRISPY m Cook gt Cook calego s a 11 AUTO COOK Sopena Cook Cock eat a o ios gt Start 12 STEAM COOK Function Desired Steam Press Stop Clear Steam Cook category Dial Food weight Start 13 QUICK START Stop Clear Start 14 MORE AND LESS Stop Clear Desired Auto Cook Dial Turn right and left LGE Internal Use Only SCHEMATIC DIAGRAM DIAGRAM SCHEMATIC
7. A OUTER CASE REMOVAL 1 Disconnect the power supply cord from the outlet 2 Remove the screws from the rear and along side edges of the case The outer case must be moved backward to be lifted off B POWER SUPPLY CORD REMOVAL 1 Remove the outer case 2 Disconnect two terminals and remove one screw of the earth terminal CAUTION DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE SERVICING refer to page 2 1 C CONTROLLER ASSEMBLY REMOVAL 1 Disconnect the leadwire from the PCB SUB ASS Y 2 Remove the screws for the earth and securing the control panel 3 Lift control panel ASS Y from the oven by the tab unhooked 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 Take off the PCB SUB ASS Y from the control panel LGE Internal Use Only Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes E DOOR 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 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 2 After replacing the door check f
8. Only for training and service purposes OPERATING SEQUENCE The following is a description of component functions during oven operation 1 MICROWAVE COOKING Stop Select Desired Press Clear Micro power level Dial Desired cooking time Start 2 GRILL COOKING Stop Select Desired Clear Grill cooking time Start 3 CONVECTION COOKING To pre heat Stop Select Desired convection Clear Convection gt temp 40 C 100 250 gt Start To cook Stop Select Desired convection Press Clear Convection gt temp 40 C 100 C 250 C Dial Desired cooking time gt Start 4 GRILL COMBINATION COOKING Select Desired Press Stop Clear Grill combi cooking level Dial Desired cooking time Start 5 CONVECTION COMBINATION COOKING Select Desired Press Stop Clear Conv combi cooking level Dial Desired Conv temp Press Desired gt 100 2509 gt Dial cooking time Start 6 STEAM KEEP WARM Select Steam Desired Warming temp Stop Clear Keep Warm Hi Low Desired Press Dial Warming time Start Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes 4 2
9. P C B assembly Continuity m Loose connection gt um Hen 2 Fan motor or Defective fan Replace fan oven lamp Check fan motor H gt Abnormal poe motor i do not turn on Defective oven Replace oven na Check oven lamp Abnormal lamp lamp 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 Normal utility co or qualified electrician Disconnect the wire leads from Defective P C B Re place P C B relay 2 and check Annormak assembly assembly on and off time with multitester Normal Measure the Abnormal Defective Replace output power magnetron magnetron NOTE Simple test of power output conducted by heating one liter water for one min if available Minimum 8 5 C temperature rise is normal condition Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes 5 16 LGE Internal Use Only TROUBLE 5 No microwave oscillation even though oven lamp and fan motor run Display operates pro
10. glass vessel having a maximum material thickness of 3 mm and an outside diameter of approximately 190 mm The oven and the empty vessel are at ambient temperature prior to the start of the test initial temperature 1 of the water is 10 2 C It is measured immediately before the water is added to the vessel After addition of the water to the vessel the load is immediately placed on the center of the shelf 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 in seconds and AT is the temperature rise The initial and final water temperatures are selected so that the maximum difference between the final water temperature and the ambient temperature is 5 The microwave power output in watts is calculated from the following formula 4187 x AT 0 55 X T2 To X M T P T Temperature after heating Temperature of bowl e M Weight of bowl is measured while the microwave generator is operating at full power Magnetron filament heat up time is not included 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 heat WATER LOAD TURNTABLE DISASSEMBLY AND ADJUSTMENT
11. Remove the turntable motor cover The turntable base cover is easily removed by pinching the eight 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 Y 7 After repairing the motor rotate the removed turntable motor cover 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 NOTE 1 Remove the wire lead from the turntable motor VERY CAREFULLY 2 Be sure to grasp the connector not the wires when removing Wire Leads Turntable Motor Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes L C MOTOR AND SHEATH HEATER REMOVAL 1 Remove the air guide and the air duct 2 Disconnect the leadwire from the circulation motor and the sheath heater 3 Remove four hex nuts securing the chamber guide assembly to the oven cavity 4 Remove a hex nut securing the circulation fan to the shaft of the circulation motor 5 Remove four screws securing the sheath heater and the chamber 6 Remove two hex nuts securing the circulation motor to the chamber Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes 5 6 M INTERLOCK SYSTEM 1 INTERLOCK MECHANISM The door lo
12. Use Only Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes SPECIFICATIONS MODEL MC 3089NBC Power Requirement 230 V 50 Hz Single phase 3 wire grounded Microwave 1350W Grill 1 250W Combination max 2 550W Convection max 2 050W Power Output 900 Watts full microwave power 60705 Microwave Frequency 2 450 MHz 50 MHz Magnetron 2M214 39F Timer 0 99 min 59sec Outside Dimensions 530 W x 322 H x 427 D mm Cavity Dimensions 348 W x 233 H x 366 D mm Net Weight 19 kg Shipping weight 21 kg Control Complement Microwave Power for Variable Cooking Power level max 900W Full power throughout the cooking time MED HIGH 720W approx 8096 of Full power MEDIUM 540W approx 6096 of Full power DEFROST 360W approx 4096 of Full power LOW WARM 180W approx 2096 of Full power CONVECTION max 250 C GRILL COMBINATION Rating Label Location Accessories Owner s manual amp Cook book Glass turntable Rotating ring Rack Steam cover Steam plate Steam water bowl Small crisping tray Large crisping tray 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 LGE Internal Use Only Only for training and service purposes CAUTIONS Unlike other appliances the microwave oven is hig
13. gt Check me No continuity Loose connection gt cone mom 01 connnection tightly between thermistor and Continuit assembly eee Check the Defective thermistor Replace the thermistor abnormal Thermistor shorted thermistor Defective Replace the Moral P C B Assembly P C B assembly CONDITION CHECK RESULT CAUSE REMEDY E ispla yisnows the No continuity Loose connection gt Connect them E02 connnection tightly between Thermistor and Continuit P C B assembly Defective thermistor Replace the thermistor Thermistor opened thermistor Normal I Check the heater Abnormal hearer Heater opened heater Defective Replace the Normal P C B Assembly P C B Assembly LGE Internal Use Only 5 19 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes EV EXPLODED VIEW INTRODUCTION MODEL MC 3089NBC OVEN CAVITY PARTS INTERIOR PARTS ae IN dii X Vig v J Rey m BASE PLATE PARTS DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS LGE Internal Use Only 6 1 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes EV DOOR PARTS
14. 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 5 1 NECESSARY MEASURING INSTRUMENTS TESTER VOLTS DC AC Ohmmeter Microwave survey meter Holaday 1500 1501 Narda 8100 8200 Inch scale 600 cc non conductive material beaker glass or plastic inside diameter approx 8 5 31 2 in Cylindrical and made of borosilicate glass vessel max thickness 3 mm outside diameter approx 190mm height approx 90mm e 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 2 450 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
15. CK RESULT CAUSE REMEDY Output is full when Disconnect the Abnormal Defective P C B Replace P C B you set lower wire leads from i i 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 Malfunction the operating m Heater gt Abnormal gt heater Replace Normal Thermostat and Malfunction the relay3 Grill AROMA thermostat Normal TM Replace or Wire connection No continuity Open or loosen connect tightly 1 Lower tempera Malfunction the ture the oven Heater Abnormal gt heater Replace Normal Thermostat and Malfunction the relay3 Grill Abnormal thermostat ad NOTE Make sure the wire leads are in the 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 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes 5 18 LGE Internal Use Only TROUBLE 8 Display shows error mode CONDITION CHECK RESULT CAUSE REMEDY Spa
16. FUSE SWITCH O O 3 MONITOR TRANS SWITCH FORMER Aaa SECONDARY 22 SWITCH CONTROLLER OD PRIMARY FUSE SWITCH MONITOR TRANS SWITCH FORMER SECONDARY LY SWITCH MICOM VN 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 4 000 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 power of microwave oven as POWER LEVEL refer to page 1 1 One complete cycle of relay 2 is 22 seconds Copyright O 2007 LG Electronics Inc All right reserved Only for training and s
17. 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 is moved horizontally along the oven surface this 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 oven supplied at its rated voltage and operated at its maximum microwave power setting with a load of 1000 5 g potable water The water is contained in a cylindrical borosilicate
18. ansformer voltage NOTE All these switches must be replaced at the same time Refer to page 5 6 5 7 2 Fuse does not blow LGE Internal Use Only Defective mag netron thermostat Replace mag netron thermostat Check continuity _ No continuity of magnetron thermostat Continuity Check continuity ae gt of power supply No continuity cord 5 15 Defective power supply cord o Replace power supply cord Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes 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 not count down when touching gt of secondary switch with door closed Check continuity No continuity Defective secondary switch Replace secondary switch START pad L continuity L Check the con nection between TES Defective P C B Replace P C B gt gt a connector and assembly assembly
19. ck mechanism 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 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 ADJUSTMENT DIRECTION PRIMARY INTERLOCK SWITCH INTERLOCK MONITOR SWITCH SECONDARY INTERLOCK SWITCH LGE Internal Use Only INTERLOCK CONTINUITY TEST WARNING FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION EMISSION REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS TYPE SZM V 16 FA 63 OR VP 533A OF OR V 5230Q FOR PRIMARY SWITCH NO SZM V 16 FA 62 OR VP 532A OF V 5220Q FOR MONITOR SWITCH TYPE NO SZM V 16 FA 63 OR VP 533A OF OR V 5230Q FOR SECONDARY SWITCH A PRIMARY INTERLOCK SWITCH TEST When the door is closed slowly an audible click should be heard at the same time or successively at intervals When the door is opened 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 adjustm
20. d service purposes 4 3 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 Each indicator light turns on to indicate that the stage has been set WHEN TOUCHING THE START BUTTON 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 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 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
21. eguide 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 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 or shelf that is WARNING strong enough to hold the oven and the food and 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 wire
22. eir aluminum foil characteristics 2 Use plastic wrap or lid 3 Stir once or twice while cooking soup cocoa or milk etc LGE Internal Use Only 5 13 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes TROUBLE 1 The following visual conditions indicate a probable defective control circuit 1 Incomplete segments 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 10 Each indicator light does not turn on after setting cooking cycle 11 Display time of day does not reappear when cooking is finished 12 Beep sound is not heard when correct key is touched different from one touched 3 Random programming when touching other pads 4 Display is fixed at some figure and can not accept any input Copyright O 2007 LG Electronics Inc All ri
23. ent 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 closed 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 SWITCHES
24. ervice purposes WHEN TOUCHING THE START KEY WITH THE CONVECTION 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 the oven thermal cut out as shown by the solid line Turntable rotates CONVECTION HEATER 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 D 1 GRILL HEATER LGE Internal Use Only 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 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
25. esult 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 Inserting many plug into one gt Avoid using other 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 E e Insert microwave oven plug inserted tightly securely Output power is too low Low AC input voltage gt Use the microwave oven adequate line voltage Food temperature is too low This not be a defect It is possible that the food should be cooked for a longer time period Sparks occurring Using metallic ware and gt 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 Inconsistent intensity of LL 1 Wrap the thinner part with microwave by th
26. etron To prevent microwave leakage tighten the mounting screws properly making sure there is no gap between the waveguide and the magnetron Air Duct LGE Internal Use Only H 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 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 J 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 voltage transformer to the baseplate Noise Filter T LGE Internal Use Only K THE TURNTABLE MOTOR REMOVAL 1 Remove the turntable 2 Remove the turntable shaft VERY CAREFULLY with a slotted screwdriver 3 Lay the unit down on its back 4
27. ght reserved CONDITION CHECK RESULT CAUSE REMEDY 1 Some inputs Check the Everything works Defective key Replace key cannot be connection as specified membrane membrane programmed between assembly assembly leadwire connector and i 2 Display shows a Still have trouble Defective PCB Replace PCB number or figure PCB assembly assembly assembly Only for training and service purposes 5 14 LGE Internal Use Only 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 continuity ae Malfunction of the Replace primary 1 Fuse blows gt Continuity monitor switch and monitor switch with switches door closed No continuity Replace fuse capacitor and operate the unit gt Check continuity Continuity Shoned este Replace primary otpnmary the primary switch and monitor switch with switches door opened No continuity Disconnect one oral Defective high Replace high side of the wire voltage capacitor voltage capacitor lead connected from transformer A blows e Defective high volt Replace high volt to the high 9 age transformer age tr
28. h 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 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 cavity 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 wav
29. hen the oven is empty to the terminal in the plug which is marked with the letter L or colored red 10cm Copyright 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 Control Panel STEAM PLATE STEAM WATER BOWL Small Crisping Tray CONTROL PANEL 1 DISPLAY WINDOW Used to show time of day power level of cooking cooking category 2 MODE To select micro mode grill mode grill combination mode steam keep warm mode ez clean mode speed hot air mode convection A combination mode and convection mode 3 QUICK DEFROST Used to thaw only 0 5kg of minced meat very quickly 2 m 4 AUTO DEFROST To select auto defrost T m 5 STEAM COOK Used to select the steam cook 3 4 6 LARGE CRISPY Used to large crisp cook A zy 6 7 CLOCK Used to set the time of day 8 AUTO COOK Used to select the auto cook 7 L 1 8 9 DIAL To select convection temperature change cooking time and weight 10 START QUICK START To quickly set the 9 cooking time directly 11 STOP CLEAR Used to stop oven and clear all entries except time of day 10 he LGE Internal Use Only 4 1 Copyright 2007 LG Electronics Inc All right reserved
30. his 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 PRECAUTIONS Sucia iii tina Inside front cover SPECIFICATIONS cs 1 1 CAUTIONS Sinai rea 2 1 INSTALLATIONS cidade 3 1 OPERATING INSTRUCTIONS 313 4 1 7 09 4 1 CONTROL PANEL 4 1 OPERATING 4 2 SCHEMATIC 4 3 CIRCUIT DESCRIPTION 4 4 SERVICE INFORMATION futu 5 1 TOOLS AND MEASURING INSTRUMENTS eene eene 5 1 MICROWAVE LEAKAGE TEST 5 1 MEASUREMENT OF MICROWAVE POWER OUTPUT m HII e e 5 3 DISASSEMBLY AND ADJUSTMENT 5 3 INTERLOCK CONTINUITY TEST nennen 5 7 COMPONENT TEST PROCEDURE 5 8 uzoU N een c 5 13 TROUBLE SHOOTING Display shows error mode eM 5 19 EXPLODED VIEW 6 1 REPLACEMENT PARTS LIST oca rs 7 1 LGE Internal
31. or microwave energy leakage with a survey meter Microwave energy must be below the limit of 5 mW cm with a 275 ml water load 3 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 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes F AIR DUCT ASSEMBLY REMOVAL 1 Disconnect the leadwire from lamp 2 Remove the mounting screw to the cavity G MAGNETRON REMOVAL 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 NOTE 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 be sure that the gasket is in good condition 3 After replacing the magnetron check for microwave leakage with a survey meter around the 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 magn
32. perly CONDITION CHECK RESULT CAUSE REMEDY No microwave Disconnect the Defective P C B Replace P C B ies No continuity gt oscillation wire leads from assembly assembly relay 2 and check continuity of relay2 Continuity Operate the unit Check Defective high Replace high transformer pe Agma voltage voltage transformer transformer normal Check H V EROR Defective high Replace high capacitor voltage capacitor voltage capacitor normal Check H V Defective high Replace high diode Abnontial voltage Diode voltage Diode normal LGE Internal Use Only Check Abnormal Magnetron Defective magnetron Replace magnetron 5 17 Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes TROUBLE 6 Oven does not cook properly when programmed for the set power level Operates properly on HIGH CONDITION CHE
33. s 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 7 As the colors of the wires the mains lead of this appliance may not correspond with the colored markings identifying the terminals in your plug proceed as follows 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 The wire which is colored green and yellow must be connected to the terminal in the plug which is marked with the letter or by the earth symbol or colored green or green and yellow 7 Place the microwave oven as far away as possible from TV RADIO COMPUTER etc to prevent interference 8 Do not touch the front glass during or after cooking The wire which is colored blue must be connected to of the Grill and Combination mode the terminal in the plug which is marked with the letter This glass is very hot during heater operating 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 w
34. sistance Ohm meter scale Rx1 Normal Less than 1 ohm Filament terminal Measure the resistance Ohm meter scale Rx1000 Normal Infinite 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 PROCEDURE RESULTS Antenna Gasket Filament Terminals 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 Ohm meter scale Rx1000 Terminal to terminal Normal Momentarily indicates several ohms and then gradually returns to infinite Measure the resistance Ohm meter scale Rx1000 Terminal to case Normal Infinite HIGH VOLTAGE DIODE NOTE Some inexpensive meters may indicate infinite resistance in both direction LGE Internal Use Only Measure the continuity Forwara Ohm meter scale Rx10000 CO S Normal Continuity Abnormal Infinite Measure the continuity Reverse Ohm meter scale Rx10000 Normal Infinite Abnormal Continuity 5 9 Copyright 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 multi meter Abnormal
35. 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 Copyright O 2007 LG Electronics Inc 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 components 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 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 removed less 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
36. veral ohm TURNTABLE Measure the resistance Normal Approx 10 20 kohm MOTOR Ohm meter scale R x 1000 Abnormal Infinite or several Wire leads removed ohm LGE Internal Use Only 5 11 Copyright O 2007 LG Electronics Inc All right reserved Only for training and service purposes COMPONENTS TEST PROCEDURE RESULTS CIRCULATION MOTOR Normal COM 230V Approx 160 Wire leads removed Abnormal Infinite or several ohm NOTE MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON MAKE SURE THE WIRE LEADS ARE CORRECT POSITION WHEN REMOVING THE WIRE LEAD FROM THE PARTS BE SURE TO GRASP THE CONNECTOR NOT THE WIRES Copyright O 2007 LG Electronics Inc All right reserved 5 12 LGE Internal Use Only Only for training and service purposes TROUBLE SHOOTING WHEN YOU 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 r
Download Pdf Manuals
Related Search