MICROWAVE OVEN SERVICE MANUAL
Contents
1. Oven Front Plate Window Door Screen Control Panel Door Seal High Rack Low Rack Metal Tray 1 DISPLAY WINDOW Used to show time of day cooking of veg cooking of power level cooking category Auto Roast 160 2 3 2 TIMER You can use the timer function of your er Aut oven for purpose other than cooking RER 4 3 CLOCK Used to the time of day PAL 5 4 AUTO ROAST 5 6 2 6 AUTO COOK Used to cook the foods listed by one L touch 1 8 7 CLEANING Used to remove smell in the oven 8 DIAL To set cooking times or weight 9 QUICK DEFROST Used to select the auto weight 9 defrost Org 10 10 AUTO WEIGHT DEFROST Used to select the 4 4857 auto weight defrost 11 11 STOP CLEAR Used to stop over and clear all entries except time of day 2 O 12 12 START Q START One tap allows over to begin 3 functioning 4 1 OPERATING SEQUENCE The following is a description of component functions during oven operation 1 SETTING THE CLOCK Stop Clear Clock hou Desired r Desired minute Start 2 MICROWAVE COOKING Stop Clear Function Desired power level Start cooking Desired time Start 3 MULTI STAGE COOKING Stage 1 Stop Clear Desired power level Y2. Start gt Desired cooking time Stage 2 Desired power level Start Desired cooking time gt gt Start 4 GRILL COOKING Stop Clear Function Grill Desired cooking time yo Start 5 CONVECTION COOKING To pre heat Stop Clear Function gt Convection Desired convection temp 40 C 100 C 250 C Start To cook Stop Clear Function gt Convection Desired convection temp 40 C 100 C 250 C Start Desired cooking time Start 4 2 6 COMBINATION COOKING To Grill Co mbi Stop Clear gt Function Combi 1 Desired power level Start To Grill Co mbi Desired cooking time gt Start Stop gt gt Clear Function Combi 2 Desired convection gt temp 40 C 100 C 250 C Start Desired power level 20 60 m Desired cooking time gt Start 7 AUTO WEIGHT DEFROST Stop Clear I Desired category defrost Food weight Start 8 AUTO ROAST Stop Clear gt Desired Auto Roast category
3. Malfunction the relays Grill Abnormal thermostat Normal i IR Replace or Wire connection gt No continuity gt Open or loosen connect tightly 1 Lower tempera Malfunction the ture the oven Heater gt Abnormal Replace Normal Thermostat and Malfunction the relay3 Grill Abnormal 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 5 18 EXPLODED VIEW INTRODUCTION OVEN CAVITY PARTS INTERIOR PARTS LATCH BOARD PARTS BASE PLATE PARTS DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS 6 1 DOOR PARTS 6 2 CONTROL PANEL PARTS CAVITY PARTS 6 4 LATCH BOARD PARTS Vio Y gt 6 5 INTERIOR PARTS 6 6 BASE PLATE PARTS 6 7
4. Monitor Switch mad Secondary Switch ag NOTE After checking for the continuity of switches make sure that are correctly connected 5 7 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 TERMINAL SECONDARY TERMINAL PRIMARY TERMINAL 1 Measure the resistance Ohm meter scale Rx1 and Rx100 Primary winding Approx 1 4 ohm Secondary winding Approx 90 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 resistance Ohm meter scale Rx1 Normal Less than 1 ohm Filament terminal Measure the resistance Ohm meter scale Rx1000 Normal Infinite Filament to chassis 5 8 5 TEST PROCEDURE RESUL
5. Start 9 AUTO COOK Stop Clear gt Desired auto cook category Food weight Start 10 CHILD LOCK This oven has a CHILD LOCK feature To Set CHILD LOCK Stop Clear I gt Stop Clear Touch and Hold To Cancel CHILD LOCK Stop Clear I y Stop Clear Touch and Hold 11 QUICK START Stop Clear I gt Start 12 MORE AND LESS Stop Clear Desired auto cook More Less SCHEMATIC DIAGRAM 0381415 MOTIZA ANY N3399 4 9 YOLOW NOILWINDAIO YOLOW 318 1 NYAL WILL dWV1 TO YOLOW W4 MOV 18 19 1714 I3MOHI lt punou 5 55042 jo 46 4 ayy Buoys Aq 101209035 ybiy ayy ONOIANAS 340438 39VL10A LAVH 30 A1l9VYdVD 1 9 13 Y3193NNO930 SNODINHOSL 1 5 JOA NQNOLHOV YOLSINYIHL ALIHM HM GP Rel
6. 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 Air Duct 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 I 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 REMOVING THE TURNTABLE MOTOR 1 Remove the turntable 2 Remove the turntable shaft VERY CAREFULLY with a slotted screwdriver 3 Lay the unit down on its back 4 Remove the turntable motor cover The turntable base cover 15 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 Y 7 After repairing
7. 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 15 interrupted with the door in a slightly opened position less than 2 mW cm sq 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 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 15 manufacturer MEASUR
8. a Sunil MOTA 30718 18 xf 41 5 Es IE HOLIMS 40 SI 310 41 419945 IND oun NOYLINIVN h 18 Bee i ew __ IO CN el si z 3SION 30010 A ed O ae 4 3 HM w 5 9 5 ot ro EE M n HOLIMS 5 SOLINON a Sen e 1 YOL93L10Yd 5 E 1 gt l He b4 ag Le ee YINYVOISNVAL Ir NH HOLIMS 4 3 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 PAD The coil of the relay 15 energized by the micom controller Power input is supplied to the high voltage transformer through the fuse to the primary switch and relay 2 Turntable rotates power of microwave oven as POWER LEVEL refer to page 1 1 One complete cycle of r
9. heat the magnetron filament through two noise preventing choke coils A high voltage of approximately 2100 volts AC 15 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 15 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 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 ae Wire GRILL HEATER RELAY 3 Turntable rotates The fan motor rotates The air 15 also directed into the oven to exhaust the vapor in the oven through the base plate and upper plate 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 M
10. 100M ohm insulation resistance meter Normal more than 0 5 Mohm NOTE Make sure heater 15 fully cooled when tested MAGNETRON THERMOSTAT 0 C Approx 90 C Approx 90 C o GA 0 C Approx 145 C Approx 145 C EA 5 10 AN 5 TEST PROCEDURE RESULTS Disconnect the 8 pin connector from P C B Refer to schemetic diagram Check for P C B connector Cooking Start LA 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 TA FAN MOTOR Wire leads removed Measure the resistance Ohm meter scale R x 1 Normal Approx 200 400 ohm A Approx 30 50 ohm B Approx 300 500 ohm Abnormal Infinite or several ohm TURNTABLE MOTOR Wire leads removed Measure the resistance Ohm meter scale R x 1000 Normal Approx 10 20 kohm Abnormal Infinite or several ohm NOTE A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION WHEN REMOVING THE WIRE LEADS FROM THE PARTS BE SURE TO GRASP THE CONNECTOR NOT THE WIRES 5 11 5 TEST PROCEDURE RESULTS CIRCULATION MOTOR Measure the resi
11. EMENT 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 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 The 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 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 15 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 15 5 K The microwave power output P in watts is calculated from the following formula 4187 x AT 0 88 X To X M T T2 Temperature after heating To Temperature of bowl M Weight of bowl is measured while the microwave generator 15 operating at full power Magnetron filament heat up time 15 not included The wate
12. ICROWAVE 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 crr Always start measuring of an unknown field to assure safety for operating personnel from radiation leakage 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 31 2 in Cylindrical and made of borosilicate glass vessel max thickness 3 mm outside diam
13. INUITY TEST 5 7 COMPONENT TEST PROCEDURE otccroincicinninnciicnonesi narcarnacano rocio carnero raras 5 8 5 13 EXPLODED 6 1 REPLACEMENT PARTS LIST re ee enge 7 1 SPECIFICATIONS MODEL MC 766YS Power Requirement 230 Volts AC 50 Hz Single phase 3 wire grounded Microwave 1300W Grill 1250W Combination 2650W Convection 1350W Max 2550W Power Output 900 Watts full microwave power IEC60705 Microwave Frequency 2450 MHz Magnetron 2M214 39F Timer 0 90 min Outside Dimensions 515 W x 303 H x 510 D mm Cavity Dimensions 342 W x 215 H x 338 D mm Net Weight 20 7 kg Shipping weight 22 5 kg Control Complement Microwave Power for Variable Cooking Power level MAX 900W Full power throughout the cooking time MED HIGH 720W approx 80 of Full power MEDIUM 540W approx 60 of Full power DEFROST 360W approx 40 of Full power LOW WARM 180W approx 20 of Full power CONVECTION Max 250 C GRILL COMBINATION Nameplate Location Back Side Accessories Owner s manual amp Cook book Glass turntable Rotating ring Grill rack Convection rack Metal tray This microwave oven is designed for household use only It is not recommended for commercial purposes 1 1 CAUTIONS Unlike other appliances the microwave oven 15 high voltage and high current equipment Tho
14. TS Antenna 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 Measure the continuity Forward Ohm meter scale Rx10000 Normal Continuity Abnormal Infinite Measure the continuity Reverse Ohm meter scale Rx10000 5 9 Normal Infinite Abnormal Continuity 5 TEST PROCEDURE RESULTS FUSE Check for continuity of the fuse with an Normal multi meter Abnormal NOTE If the fuse is blown check the primary the secondary and switches H V D and H V C before replacing the fuse the monitor 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 38 at 20 30 C Measure the resistance with 500V
15. Website http biz Igservice com LG MICROWAVE OVEN MODEL MC 766YS CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL August 2004 P NO 3828W5S3953 Printed in Korea SAFETY PRECAUTIONS This device is to be serviced only by properly qualified service personnel Consult the service manual for proper service procedures to assure continued safety operation and for precautions to be taken to avoid possible exposure to excessive microwave energy PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY A Do not operate or allow the oven to be operated with the door open B Make the following safety checks on all ovens to be serviced before activating the magnetron or other microwave source and make repairs as necessary 1 interlock operation 2 proper door closing 3 seal and sealing surfaces arcing wear and other damage 4 damage to or loosening of hinges and latches 5 evidence of dropping or abuse C Before turning on microwave power for any service test or inspection within the microwave generating compartments check the magnetron wave guide or transmission line and cavity for proper alignment integrity and connections D Any defective or misadjusted components in the interlock monitor door seal and microwave generation and transmission systems shall be repaired replaced or adjusted by procedures described in this manu
16. al before the oven is released to the owner E A microwave leakage check to verify compliance with the Federal Performance Standard should be performed on each oven prior to release to the owner CAUTION MICROWAVE RADIATION DO NOT BECOME EXPOSED TO RADIATION FROM THE MICROWAVE GENERATOR OR OTHER PARTS CONDUCTING MICROWAVE ENERGY CONTENTS Page SAFETY PRECAUTIONS usa Inside front cover SPECIFICATIONS 1 1 CAUTIONS tada atada 2 1 INSTALLATION S 20 RR 3 1 OPERATING INSTRUC TIONS ss en 4 1 FEATURES as 4 1 CONTROL PANEL cinc cicle aras 4 1 OPERATING 4 2 SCHEMATIC DIAGRAM 4 3 CIRCUIT DESCRIPTION 4 4 SERVICE INFORMATION Seinen 5 1 TOOLS AND MEASURING INSTRUMENTS 5 1 MICROWAVE LEAKAGE TEST u sccococnncnicnnnnirn cancionero arco ciernes 5 1 MEASUREMENT OF MICROWAVE POWER OUTPUT 5 3 DISASSEMBLY AND ADJUSTMENT s ss sesssesissesseestsussaessnsnensctoesssntessssasessstriensnesineniantans 5 3 INTERLOCK CONT
17. ater 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 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 voltage transformer to the baseplate 5 4 F AIR DUCT ASSEMBLY REMOVAL 1 Disconnect the leadwire from lamp and MGT thermostat 2 Remove the mounting screw to the magnetron 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 cm With a 275 ml water load
18. dicate 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 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 TEST PROCEDURE RESULTS SWITCHES Check for continuity of the switch Wire leads removed with a Multi meter Door Door open close Primary Switch EN a
19. e 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 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 Insert microwave oven plug inserted tightly securely Output power is too low Low AC input voltage m 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 m 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 le ya Do not use any type of gold or silver powder is used cookware with metallic trimming Uneven cooking Inconsistent intensity of __ 1 Wrap the thinner part with microwave by their aluminu
20. e danger resulting from the microwave leakage 2 MOUNTING OF THE PRIMARY MONITOR SECONDARY SWITCHES TO THE LATCH BOARD Right ADJUSTMENT DIRECTION PRIMARY SWITCH Left SECONDARY SWITCH MONITOR 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 5 6 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 in
21. eck the conn ie Defective PCB Replace PCB ection between assembly assembly membrane key assembly and e Loose Connect them PCB assembly connection tightly 2 Some 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 a gt Still have trouble Defective PCB Replace PCB number or figure assembly assembly 5 14 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 aan Continuity gt m hitor A and monitor switch with switches door closed gt continuity Replace fuse Replace primary Check continuity Continuity m Shorted contact at gt of primary the primary switch and MONNA switch with switches door opened No continuity Disconnect one ll Nirmal ae Defective high Replace high side of the wire voltage capacitor voltage capacitor lead connected from transformer Fuse bl Defective high volt Replace high volt to the high 7056 Diows age transformer age tra
22. elay 2 15 22 seconds 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 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 HV 3 MONITOR TRANS SWITCH FORMER BE SECONDARY i 99 SWITCH CONTROLLER OD PRIMARY FUSE SWITCH 1 HV 7 MONITOR TRANS SWITCH FORMER O 1 SECONDARY RELAY ER 9 SWITCH 1 CONTROLLER YN 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 15 generated from the filament winding of the high voltage transformer This 3 2 volts is applied to the magnetron to
23. eter 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 5cm 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 MEASUREMENT WITH OUTER CASE REMOVED When you replace the magnetron measure for microwave energy leakage before the outer case 15 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
24. less it 15 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 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 15 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 15 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 ge
25. m foil characteristics 2 Use plastic wrap or lid 3 Stir once or twice while 5 13 cooking soup cocoa or milk etc TROUBLE 1 The following visual conditions indicate probable defective control circuit _ 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 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 2 3 4 5 Display indicates a number different from one touched for example key in 5 and 3 appears in the display 6 7 8 Display obviously jumps in time while counting down 9 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 4 Random programming when touching other pads 5 Display is fixed at some figure and can not accept any input CONDITION CHECK RESULT CAUSE REMEDY 1 No input can be Ch
26. nerated 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 y E As the colors of the wires in the mains lead of this 5 Use microwave oven in an ambient temperature appliance correspond with ihe 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 connected to the terminal in the plug which is marked with the letter or by the earth symbol L 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 when the oven is empty to the terminal in the plug which is marked with the 10cm letter L or colored red OPERATING INSTRUCTIONS FEATURES
27. nsformer voltage capacitor and operate the unit NOTE All these switches must be replaced at the same time Refer to page 5 6 5 7 2 Fuse does not blow Defective mag netron thermostat Replace mag netron thermostat Check continuity No continuity of magnetron thermostat gt Continuity Check continuity __ of power supply cord No continuity 5 15 Defective power supply cord Replace power supply cord TROUBLE 3 Display shows all figures set but oven does not start cooking while desired program times set and START pad 15 touched CONDITION CHECK RESULT CAUSE REMEDY 1 Setting time does Check continuity continuity E O Hotcaunt dowi of secondary secondary switch secondary switch when touching switch with START pad door closed L continuity L Check the con nection between Defective P C B Replace P C B gt gt connector and assembly assembly gt P C B assembly Continuity gt Loose connection ne 2 Fan motor Defective fan Replace fan oven lamp Check fan motor gt Abnormal motor motor do n
28. ot turn on Defective oven Replace oven Check oven lamp gt Abnormal nm lamp rat 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 gt Normal utility go e qualified electrician Disconnect the wire leads from Defective P C B Replace P C B relay 2 and check Abnormal 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 5 16 TROUBLE 5 No microwave oscillation even though lamp and fan motor run Display operates properly CONDITION CHECK RESULT CAUSE REMEDY No microwave Disconnect the e Defective P C B Replace P C B continuity gt oscilla
29. r is stirred to equalize temperature throughout the vessel prior to measuring the final water temperature Stirring devices and measuring instruments selected in order to minimize addition or removal of heat WATER LOAD TURNTABLE DISASSEMBLY AND ADJUSTMENT 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 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 CONTROL PANEL ASSEMBLY 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 DOOR GROSS 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 for microwave energy leakage with a survey meter Microwave energy must be below the limit of 5 mW cm with a 275 ml w
30. stance Normal COM 230V Approx 150 Q Wire leads removed Multi meter scale R x 1 COM 24V Approx 20 Q Abnormal Infinite or several ohm NOTE WIRE COLOR RELAY 3 4 OF P C B Cooking Start Disconnect the 9 pin connector from P C B See Schematic Dagram on page 4 3 RELAY 2 3 4 OF P C B Cooking Start Wire leads removed RY5 Microwave RY4 Grill RY6 Convection KEY PCB Check continuity between switch i terminals by pressing an appropriate pad on key board The contacts assignment of the respective pads on the key board is as shown left figures NOTE A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE 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 5 12 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 th
31. the motor rotate the removed turntable motor cover 8 Fit the turntable motor cover s projecting part to the base plate slit NOTE 1 Remove the wire lead from the turntable motor VERY CAREFULLY 2 Be sure to grasp the connector not the wires when removing 5 5 Turntable Motor C MOTOR THERMISTOR AND SHEATH HEATER REMOVAL 1 Remove the two screws securing the cover assembly to the oven cavity 2 Disconnect the leadwire from the circulation motor terminal and the sheath heater 3 Remove the screws of the thermistor guide assy chamber and lift up the guide assy chamber 4 Remove a hex nut securing the circulation fan to of the C motor 5 Remove screws securing the motor bracket to the guide assy chamber 6 Remove two hex nuts securing the C motor to the motor bracket L 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 Control Panel M INTERLOCK SYSTEM 1 INTERLOCK MECHANISM The door lock mechanism 15 a device which has been specially designed to eliminate completely microwave activity when the door is opened during cooking and thus to prevent th
32. tion wire leads from assembly assembly relay 2 and check continuity Continui of relay2 gt Continuity _ Operate the unit Check H V Defective high Replace high transformer 2 voltage voltage transformer transformer gt normal Check H V Abiornal Defective high Replace high capacitor voltage capacitor voltage capacitor normal Check H V diode Abnormal Defective high voltage Diode Replace high voltage Diode TX normal Check Magnetron Abnormal Defective magnetron Replace magnetron 5 17 TROUBLE 6 Oven does not cook properly when programmed for the set power level Operates properly on HIGH 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 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 Heater gt Abnormal gt heater Replace Normal Thermostat
33. ugh 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 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 un
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