MICROWAVE OVEN SERVICE MANUAL
Contents
1. _ WELL DONE 6 MEAT 3 POULTRY cle 7 haya sxe 1 MEAT e DEFROST 2 POULTRY glas dO ONE TOUCH CONTROL PLATE OF FOOD 1 POPCORN 3 BAKED GOODS REHEAT COOK 1 PLUS TIME dated EOS MICRO TIME MICRO POWER HOLD WARM eos lo yy AGL 225 F 250 275 300 F 325 F 350 F 375 F 400 F 425 F 450 F CLOCK STOP CLEAR START DISPLAY WINDOW Used to show Time of day Cooking time Cooking power level Cooking temperature t also functions as a countdown timer or temperature indicator when cooking COMBINATION HIGH LOW Used in setting combination high or low cooking AUTO COOK Used in setting weight combination cooking Auto Combination Guide is next to the pad DEFROST Used in setting Auto Defrost POPCORN Used to pop pack aged popcorn PLUS TIME Used to cook food for a longer time after cooking end HOLD Used to keep the food warm NUMBERS Used to enter the Time of day Cooking times Cooking powers Cooking temperatures Weight for Auto Combination cooking START Starts the oven NOTE A beep tone sounds when a pad on the control panel is touched to indi2. Microwave Frequency 8 High Voltage Capacitor High Voltage Diode nennen Oven Lamp e HH HH ES Power Control HHHHHHHH IHR Outer Dimension Cavity Dimension Safety Device 1 60705 Rating Standard 120 VAC 60 Hz 1400 Watts Microwave 12A 1580 Watts Convection 13 2A 850 Watts Microwave 1500 Watts Convection 2450 MHz 50 MHz 0 911 2100V AC HVR IX 125V 25W 99 mim 99 sec Microwave Convection and Combination MICOM 15 x 221 4 x 19 15 H x W x D 108 6 x 14 x 14 6 H x W x D Primary Interlock Switch Secondary Interlock Switch Monitor Switch Fuse 15 Amp Magnetron Thermostat Open at 145 C 6 C Close at 60 15 Oven Thermostat Open at 130 C 6 C Close at 60 15 Specifications are subject to change without notice 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 ca
3. NOTE When Child Lock is selected STOP CLEAR must always be touched before selection At this time the oven will operate normally but Micro Power and Heater Power will be zero and cooking can not take place At this time if you start to cook L will appear in the display window for 1 sec at first 14 To Cancel Child Lock 1 Touch 0 more than 2 seconds NOTE When you cancel Child Lock STOP CLEAR must always be touched before selection MULTI STAGE COOKING Let s start to cook with a first stage 4 minutes at the cooking power HI followed by a second stage of 10 minutes at cooking power 60 Touch MICRO TIME Touch 4 0 and 0 in sequence Touch MICRO TIME Touch 1 0 0 and 0 in sequence Touch MICRO POWER Touch 6 Touch START NOOR WD NOTE There are three memory stages SCHEMATIC DIAGRAM SYSTEM 1 STAND BY CONDITION Set up Door is opened Oven power cord is plugged into standard 120 volt ground outlet Normal operation Oven light turns on e In THERMOSTAT 2 OVEN FUSE 5 O O 3 O O z PO 2 OVEN LAMP T 5 of 2 O 9 5 P 5 2 a 3 TURNTABLE MOTOR ds 53 0000 m E Ey 20 RELAY3 JJ aa 5 FAN MOTOR E RELAY4 E P wm B z T CIRCULATION MOTOR
4. The air heated by the heating element is circulated through the convection passage provided on the back side of the oven by means of the convection fan which is driven by the convection motor It then enters the inside of oven through the vent holes provided on the rear of the oven cavity Next the hot air heats up the food on the turntable and leaves the oven cavity through the vent in the centre of the oven cavity rear wall Without leaving the oven this hot air is reheated by the heating element passes through the convection passage and enters the inside of the oven cavity again in a continuing cycle DAMPER OPERATION When the oven starts convection and combination function damper bracket is pulled by solenoid so that the hot air does not leave the cavity When the function is microwave the power supply to the solenoid is turn off and damper spring push the damper bracket so that the fan circulate the air within the cavity FOOD CONVECTION RACK 21 NECESSARY TOOLS AND MEASURING INSTRUMENTS NECESSARY TOOLS NECESSARY MEASURING INSTRUMENTS Tools normally used for TV servicing are sufficient Tester Volt DC AC ohmmeter Standard tools are listed below Inch scale Diagonal pliers Electromagnetic radiation monitor Long nose pliers 600 cc glass beaker or equivalent Cross head screwdriver Glass thermometer 100 C e Socket wrench size 5 mm Two 1 liter beakers or equivalen
5. See page 39 Defective thermistor Test procedure thermistor See page 40 Defective circulation motor Test procedure circulation motor See page 38 Defective drive mechanism of circulation fan Check and repair Defective Solenoid Test procedure solenoid See page 39 Defective air duct assembly NOTE MAKE SURE THE WIRE LEADS CORRECTLY POSITIONED WHEN REMOVING THE WIRE LEADS FROM THE PARTS BE SURE TO GRASP THE CONNECTOR AND NOT THE WIRES Check and repair WHEN REMOVING THE MAGNETRON BE SURE TO INSTALL THE MAGNETRON GASKET IN THE CORRECT POSITION AND GOOD CONDITION dba COMPONENT TEST PROCEDURE CAUTIONS 1 DISCONNECT THE POWER SUPPLY CORD FROM THE WALL OUTLET WHENEVER REMOVING THE OUT CASE FROM THE UNIT PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER SEE FIGURE 24 2 ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD 1 LITER OF WATER IN A BEAKER IN THE OVEN FILAMENT WINDING SECONDARY TERMINAL WIRE SEADS WHITE WHITE FOR PRIMARY WINDING jj H V CABLE ASM A WIRE LEAD RED RED FOR PRIMARY WINDING Fig 24 e TEST PROCEDURE COMPONENTS TEST PROCEDURE RESULTS See Fig 24 1 Measure the resistance Ohm meter scale R x 1 H
6. E will appear in the display window with two short and one long beep sounds Only STOP CLEAR can be operated while an error condition exists If you accidentally touch more than 4 numbers the last 4 numbers you have touched will appear in the display window If a momentary power failure occurs the clock display returns to zero 0 If this occurs please reset the clock If STOP CLEAR is touched or door is opened after cooking the TIME OF DAY will appear in the display window If you don t set the time of day the display counts up per minute REGULAR TIMER 1 Touch MICRO TIME 2 Touch numbers for desired time 3 Touch MICRO POWER 4 Touch 0 5 Touch START MICRO TIME COOKING 1 Touch MICRO TIME 2 Touch numbers for desired cooking time 3 Touch MICRO POWER 4 Touch number for desired cooking power 5 Touch START CONVECTION COOKING To Preheat 1 Touch CONVECTION 2 Touch number for desired preheating temperature 3 Touch START NOTE After oven temperature reached the selected temperature the oven will automatically begin to hold operation at the preheat temperature for 30 minutes To Cook 1 Touch CONVECTION 2 Touch number for desired oven temperature 3 Touch numbers for desired cooking time 4 Touch START NOTE e Convection cooking temperatures range from 225 to 450 F When oven doesn t reach selected temperature oven temperature will appear
7. STAGE 2 STAGE 3 HOLD WARM Cooking program can be partially and independently selected Example AUTO WEIGHT DEFROST STAGE 1 STAGE 2 STAGE HOLD WARM AUTO WEIGHT DEFROST STAGE 1 STAGE 2 STAGE AUTO WEIGHT DEFROST STAGE 1 STAGE 2 HOLD WARM AUTO WEIGHT DEFROST STAGE 1 STAGE 2 AUTO WEIGHT DEFROST STAGE 1 HOLD WARM AUTO WEIGHT DEFROST STAGE 1 AUTO WEIGHT DEFROST HOLD WARM AUTO WEIGHT DEFROST STAGE 1 STAGE 2 STAGE 3 HOLD WARM STAGE 1 STAGE 2 STAGE STAGE 1 STAGE 2 HOLD WARM STAGE 1 STAGE 2 STAGE 1 HOLD WARM STAGE 1 HOLD WARM AUTO WEIGHT COMBINATION REHEAT POPCORN 11 OPERATING INSTRUCTIONS TO SET THE TIME OF DAY 1 When the oven is plugged in the display window will show zero 0 2 Touch CLOCK 3 Touch numbers for correct time of day 4 Touch CLOCK again NOTE f your oven does not operate properly unplug the oven from the 120 volt household outlet and then plug it back in To reset the time of day in the display window touch CLOCK again The colon will disappear Enter the correct time of day by following the above procedure Oven will operate even though the TIME OF DAY is not set If the TIME OF DAY is not set nothing will show in the display window when STOP CLEAR is touched The TIME OF DAY can be set only from 1 00 to 12 59 At invalid setting
8. Test membrane key of P C B CONDITION MICROWAVE CAUSE Oven does not go into a cook cycle when Start pad is touched TEST PROCEDURE OR CORRECTION Primary and or secondary interlock switches defective or out of adjustment Test procedure primary and secondary switches See page 25 Defective relay 1 of P C B Test procedure relay 1 of P C B See page 40 Defective membrane key of P C B Test procedure membrane key of P C B See page 41 Open or loose wiring to above components Output power is too low Check and repair wiring Defective fan motor Test procedure fan motor See page 38 Low AC input voltage 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 Defective relay 1 or 3 of P C B Output is too high when you set lower power level Test procedure relay 1 and 3 of P C B See page 40 Defective relay 1 of P C B Test procedure relay 1 of P C B See page 40 High AC input voltage Sparks occuring Use the microwave oven at adequate line voltage Using metallic ware and allowing it to touch the
9. 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 DETERMINATION OF 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 cc 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 initial temperature 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 Glass Tray 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 1022 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 K The microwave power output P in watts is calculated from the following formula 4187 x AT 0 55 X To X M T
10. step 1 3 2 Remove three screws securing the chamber wall to the chamber 3 Remove two screws securing the convection heater to the chamber 4 Pull out the convection heater diagonally with it pursed by both sides from the C Heater hanger THERMISTOR 1 Follow section 1 step 1 3 2 Pull up the thermistor 7 4 De C HEATER ASM 59 HEED 9 C FAN 9 22 29 K REMOVING PRIMARY INTERLOCK SWITCH FIG 23 1 After removing the complete control pane assembly disconnect the wire leads from the switches 2 Remove two screws holding the latch board U to the front plate flange 3 Remove the latch board U from the flange by moving it upward and push outward 4 Remove one screw securing primary switch to the latch board U 5 Remove the switch from the latch board U L REMOVING SECONDARY INTERLOCK SWITCH MONITOR SWITCH AND OVEN LAMP SWITCH FIG 23 1 Disconnect the wire leads from the switches 2 Remove two screws holding the latch board L to the front plate flange 3 Remove the latch board L from the flange by moving it upward and push outward 4 Remove the individual switch from the latch board L by removing two screws PRIMARY SWITCH OVEN LAMP SWITCH SWITCH SECONDARY SWITCH Fig 23 TROUBLESHOOTING receptacle cord is plugged into wall CAUTION 1 Check grounding before check
11. M ohm Ohm insulation resistance meter Fig 35 NOTE Make sure heater is fully cooled when tested SOLENOID Normal Approx 2200 ohm Abnormal Infinite or Several ohms COMPONENTS TEST PROCEDURE RESULTS Relay 3 of P C B Disconnect the 5 pin connector from P C B Micro Power Cooking Start A ES Relay 4 of P C B Disconnect the 5 pin connector from P C B Convection Cooking Start Relay 3 of P C B Wire leads removed Micro Power Cooking Start amos Relay 4 of P C B Wire leads removed 40 Convection Cooking Start pages COMPONENTS TEST PROCEDURE RESULTS Membrane key MEMBRANE PANEL 1 2 3 4 5 6 7 8 9 10 11 12 CONNECTOR KEY MATRIX JH 5 E AUTO COMB OMA FISH 4 POULTRY MICRO VA J STOP CLEAR 4 2 0 Check continuity between switch terminals by pressing an appropriate pad on the 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 WIRE
12. P T2 Temperature after heating Temperature of bowl 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 e Stirring devices and measuring instruments selected in order to minimize addition or removal of heat WATER LOAD GLASS TRAY Fig 44 uc EXPLODED VIEW AND PARTS LIST INTRODUCTION o H tr amp ul o E Q 5 amp 5 5 o T E 2 m 2 gt E amp lt o a E E D lt 1 MSD A 5 LLI 7 A Y E o e e Ln Y DOOR PARTS OVEN CAVITY PARTS CONTROL PANEL PARTS 44 1 DOOR PARTS 45 2 CONTROL PANEL PARTS 46 3 OVEN CAVITY PARTS 47 EV 4 OVEN INTERIOR PARTS 1 48 EV 5 OVEN INTERIOR PARTS 2 49 EV 6 SWITCHES PARTS 50 EV 7 BASE PLATE PARTS 51 EV 8 WIRING HARNESS PARTS O Sy a Y XV qu 27 y SD Y 2 DNA FOS M 918 27 Ds MOS A SL SN e uw N 52 9 CIRCUIT
13. THERMOSTAT The magnetron thermostat located on the magnetron is designed to prevent damage to the magnetron if an overheated condition develops in the tube due to abnormal state The magnetron thermostat remains closed under nor mal operation but the magnetron thermostat opens when abnormal high temperatures within the magne tron approach a critical level 145 C causing oven to shut down DOOR OPENING MECHANISM The door can be opened by pushing button and lifting the latch as a result of action by the latch spring latch and latch board jaw The latch is released from the latch board and the door can be opened PRIMARY AND SECONDARY INTERLOCK SWITCHES FIG 11 The primary interlock switch is mounted in the latch board U and secondary interlock switch is mounted in the latch board L When the door is closed the switches are activated by the latch on the door When the door is opened the switches interrupt the circuit to all components except the oven lamp MONITOR SWITCH FIG 11 The monitor switch mounted on the latch board L with the oven lamp switch is activated by a latch on the door while the door is closed If the door is opened and the primary and secondary interlock switch contacts fail to open this switch is intended to render the oven inoperative by means of fuse failure simultaneously with the closing of monitor Switch contacts OVEN LAMP SWITCH FIG 11 The oven lamp switch mounted on the la
14. replacing the magnetron be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition Fig 17 MAGNETRON 27 E REMOVING COOLING FAN MOTOR FIG 17 1 Remove the power supply cord from the oven and disconnect lead wire from the Fuse Holder 2 Disconnect each two lead wires from the Fan Motor 3 Remove three screws securing the Fan Guide Asm to the back cover and lift up the Fan Guide Asm 4 Remove two screws securing the Fan Motor to the Fan Guide after pulling out the fan from the Fan Motor F REMOVING HIGH VOLTAGE DIODE AND HIGH VOLTAGE CAPACITOR FIG 18 1 Disconnect lead wires from H V Trans and Magnetron 2 Remove one screw securing the capacitor bracket and one lead wire of H V Diode to the base plate 3 Pull the Capacitor Bracket upwards FAN GUIDE ASM FAN MOTOR G REMOVING HIGH VOLTAGE TRANSFORMER FIG 18 1 Disconnect the wire leads from the trans former to the magnetron and H V Capacitor 2 Remove four screws securing the H V Trans former to the base plate 3 Tilt the top of the H V Transformer towards you pull slightly and lift it up REMOVING TURNTABLE MOTOR FIG 19 20 21 1 Remove the turntable the rotating ring and the turntable shaft Fig 19 2 Lay the set down on its back 3 Remove the turntable motor cover of the baseplate The turntable motor cover is easily re
15. so that TV and RADIO programs are not impaired by noise WHEN TOUCHING THE START PAD WITH THE CONVECTION COOKING FUNCTION SELECTED Relay 2 is closed to provide a current path to the Convection Heater The microwave does not emit with Relay 1 open The Relay 3 4 and primary switch are closed to provide a current path to the oven lamp the turn table motor the fan motor and the circulation motor WHEN THE OVEN IS SET AT SOME COOKING POWER EXCEPT MAX COOKING POWER Micom controller controls the ON OFF time of the RELAY by the applied gets signal to vary the aver age output power of microwave oven from COOK ING POWER 10 to COOKING POWER One complete cycle of Relay is 22 seconds WHEN THE DOOR IS OPENED DURING COOKING Both primary switch and relay open to cut off primary winding voltage to the high voltage trans former ON OFF of relay is coupled electrically with open and close of secondary switch When the door is opened secondary switch is closed and when the door is closed secondary Switch is opened Function indicator light and colon turn off and dis play stops counting down Relay stops functioning As the door is opened if the contact of primary switch and relay and or secondary switch fail to open the 15 A fuse opens due to the large current surge caused by the monitor switch activation and then stops magnetron oscillation 18 MAGNETRON TUBE The magn
16. terminal of the magnetron and the outer case of the magnetron If the ohmmeter reads infinity go to below If the ohm meter reads less than infinity the magnetron is shorted Connect an ohmmeter across the terminals of the magnetron The ohmmeter should read less than one ohm If the ohmmeter reads over one ohm or infinity the tube is defective MAGNETRON WITHOUT MAGNETIC FIELD ELECTRONS CATHODE ANODE Fig 9 MAGNETRON WITH MAGNETIC FIELD 2 450 MHz ANTENNA ELECTRONS CATHODE ANODE PERMANENT MAGNET Fig 10 19 DESCRIPTION AND FUNCTION OF COMPONENTS OVEN LAMP The oven lamp illuminates the interior of the oven during cooking so that food can be seen without opening the door The oven lamp will turn off when the cooking time is ended TURNTABLE MOTOR The turntable motor rotates the turntable located on the bottom of the oven cavity during the cooking operation to cook the foods evenly Turntable will rotate in either direction OVEN THERMOSTAT The oven thermostat located on the insulator T is designed to prevent damage to the components and acts when heater overheats to abnormally high tem peratures Under normal convection operation the heater thermostat remains closed However when abnormal condition within the convection chamber approaches a critical level 130 C the oven ther mostat will open and interrupt the circuit to the oven causing it to shut down MAGNETRON
17. 36 Low AC input voltage Use the microwave oven at adequate line voltage Open or loose wiring to above components Oven operates properly on P HI but does not cook properly using another cooking power Check and repair wiring Defective relay 1 of P C B Test procedure relay 1 of P C B See page 40 Defective membrane key of P C B 34 Test procedure membrane key of P C B See page 41 CONDITION CONVECTION CAUSE CONV indicator lights but oven does not go into cook cycle when START pad is touched TEST PROCEDURE OR CORRECTION Child Lock is set This is not a defect Touch 0 key pad till a beep sounds See page 14 Defective relay 2 of P C B Test procedure relay 2 of P C B See page 40 Defective thermistor Test procedure thermistor See page 40 Open or loose wire connection to the above components Check and repair wiring Open or loose connection to P C B Temperature in the oven cavity is lower or higher than preset Check and repair wiring Defective relay 4 or 2 of P C B Test procedure relay 4 and 2 of P C B See page 40 Defective convection heater element Test procedure convection heater
18. BOARD ARI AR2 206 205 J104 88 64 564 55 54 45 44 s 3 J101 TEST POINT E J100 E EM 5580 LO 5247W2YA25 gt Jr Y vot gt SU qq 75 10 7 32 CN LAIA JN EA J02 ST TTS 9 peas R08 162 y OS 0 R02 CN LO slolgl lol M M oToToToToT 53 10 CIRCUIT BOARD SCHEMATIC DIAGRAM ROI 47K 54 020 1266 E i 10x CN2 3 E gt gt m7 DOOR A T 144148 100 si as 8 LN t ia E I J i 1 A TH D n A 223 7 bos 3 29 1K T 5 LG
19. I 2 2m o gt o 5 ze Nee a o A 2 4 RECTIFIRE FUSE z ie 1 CONVECTION HEATER n O O E 9 D RELAY2 9 52 MONITOR SWITCH 2 lt D T LS dz 5 gt 2 De 10000000007 53 z 21 5 z 8 3 9 Dm U a gt lt 1 gt li 37 1 gt Sco HIGH VOLTAGE FO E gm 108 Es DIODE Od m TIT o oc SR Ls 4 2 o9 m 15 Fig 6 SYSTEM 2 MICROWAVE COOKING CONDITION Set up Door is closed START is touched Normal operation Oven light turns on Turntable operates Fan motor operates 2 OVEN FUSE 5 OX NP 2 ero 33 538 3 59 OVEN LAMP z 5 z de m 5 O 2 r I 5 2 3 TURNTABLE MOTOR p TI O lt 2 MOTOR z O O RELAY4 P wm e z EN 5 CIRCULATION MOTOR HRE gt m m o m dE EZ 014044 gt RECTIFIRE FUSE paa 5 oy 5 O Els al 7 1 4 O O am lt A O PA m 59 RELAY2 s 9 L MONITOR SWITCH A E HOLSIWH3HL EV uaWHOdsNVvuL ADVLIOA HDIH 2 I 3 o5 m 2I gt Z5 Q IOO E gt 000 O
20. IGH VOLTAGE TRANSFORMER Wire leads removed Primary winding Secondary winding Filament winding Measure the resistance Ohm meter scale R x 1000 Primary winding to ground Filament winding to ground Approx 0 37 ohm at 20 C Approx 90 ohm at 20 C Less than 0 9 ohm Normal Infinite Normal Infinite MAGNETRON Wire leads removed See Fig 25 1 Measure the resistance Ohm meter scale R x 1 Filament terminal 2 Measure the resistance Ohm meter scale R x 1000 Filament to chassis B Normal Less than 1 ohm Normal Infinite COMPONENTS TEST PROCEDURE RESULTS ANTENNA GASKET FILAMENT NOTE When testing the magnetron be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition HIGH VOLTAGE CAPACITOR Measure the resistance Ohm meter scale Rx1000 Terminal to terminal Normal Momentary 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 Rx1000 Normal Continuity Abnormal Infinite Measure the continuity Reverse Ohm meter scale Rx1000 Normal Infinite Abnormal C
21. S 41 PROCEDURE FOR MEASURING MICROWAVE ENERGY LEAKAGE CAUTIONS Be sure to check a microwave emission prior to servicing the oven if the oven is operative prior to servicing The service personnel should inform the manufacturer importer or assembler of any certified oven unit found to have a microwave emission level in excess of 4 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 f the oven operates with door open the service personnel should Tell the user not to operate the oven Contact the manufacturer and CDRH Center for Devices and Radiological Health immediately NOTE Address on CDRH Office of Compliance HFZ 312 Center for Devices and Radiological Health 1390 Piccard Drive Rockville Maryland 20850 The service personnel should check all surface and vent openings for microwave emission testing Check for microwave energy leakage after every servicing The power density of the microwave radiation leakage emitted by the microwave oven should not exceed 2 mW cm sq And always start measuring of an unknown field to assure safety for operating personnel from radiation leakage NOTE The standard is 4 mW cm sq while in the customer s home 2 mW cm sq stated
22. U PRIMARY SWITCH LATCH BOARD L OVEN LAMP SWITCH MONITOR SWITCH SECONDARY SWITCH SWITCH LEVER 23 Fig 13 After the adjustment make sure to perform the following test This test should only be performed by authorized service personnel 1 The in and out play of the door must be less than This COM NO test should be performed with the 0 5mm when latched First check the latch board U door being opened very slowly position pushing and pulling the upper portion of 3 Re install the outer case and check for microwave door toward the oven face Then check the lower leakage Makes sure the microwave leakage is portion ot door toward the oven face Both results below the limit of 4mW cm with a 275 ml water should be less than 0 5mm load 2 Make sure the door latch closes the monitor switch and oven lamp switch after the primary switch is open NOTE A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON 24 INTERLOCK CONTINUITY TEST The service personnel should replace all of the monitored safety interlock switches and monitor switch if the oven has been rendered inoperative due to the failure of the monitored safety interlock s Be sure to connect the monitor switch after replacement and to check interlock monitor continuity COMPONENTS TEST PROCEDURE RESULTS SWITCHES Wire leads removed with an Ohm meter Check for continuity of the
23. Website http biz Igservice com LG MICROWAVE OVEN MODEL MH 1355M MH 1356M MH 1357M CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL July 1998 P NO 3828W5S6174 Printed in Korea 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 procedu
24. ble cooking power for the best results CONVECTION COOKING This is a way of cooking with hot air from the convec tion heater on the back side of the unit This method allows food to be browned evenly without losing any of the juices Heated air is circulated in the oven by a fan to enable the heating and cooking of food Since hot air remains in the oven as it circulates cooking is very efficient The temperature inside the oven can be con trolled according to the type of food being cooked COMBINATION COOKING With microwave energy and hot air this solid state control can cook alternately according to the cycles programmed between microwave and hot air to pro vide efficient cooking fully utilizing the advantages of two functions Convection rack is also used in Combi nation Cooking 10 Magnetron Circulation Convection Rack Motor Convection Heater Circulation Motor Convection Rack Fig 5 COOKING FLOW CHART CLOCK E TT A 1 ES D AUTO HOLD WEIGHT STAGE 1 STAGE2 STAGE3 WARM DEFROST AUTO WEIGHT POPCORN REHEAT COMBINATION A ES 5 Pees B 1 START Cooking procedure have five sequential programs AUTO WEIGHT DEFROST STAGE 1
25. cate a setting has been entered NOTE 1 Beep Sound The beep sound is activated under the following conditions Conditions Beep Sound Signal When the control key is touched When the cooking stage is changed pu When the preheat is ended and the holding time is begun gt When cooking is ended When an error occurs When foods need to be turned over during auto weight defrost or auto weight combination operation 2 Microwave Cooking Power Microwave cooking power can be chosen from one of the 10 cooking powers listed below If cooking power is not programmed the oven operates at cooking power HI Microwave Microwave Numbers Cooking Emission Time Numbers Cooking Emission Time of sec cycle of sec cycle Touch Pads Power Touch Pads Power OFF ON OFF 3 Digital Readout Display Time Time Temperature Clock Example 99 min Example 2 hours Example 300 F Example 12 hours and 99 sec and 30 min and 30 min Cooking Power Weight End Error Example cooking Example 4 5 Ibs power 50 HOW THE MICROWAVE CONVECTION OVEN WORKS MICROWAVE COOKING Using microwave energy only food is cooked quickly without altering its color or shape The food is evenly cooked on a rotating turntable as the microwaves produced by the magnetron Power Control can be adjusted in 10 steps enabling the various kinds of foods to cook at most desira
26. e 18 DESCRIPTION AND FUNCTION OF COMPONENTS eeee nennen nnne nnns 20 NECESSARY TOOLS AND MEASURING INSTRUMENTS 22 INSTALLATION AND ADJUSTMENT OF THE INTERLOCK SYSTEM sass 23 INTERLOCK CONTINUITY TEST Rs He 25 DISASSEMBLY AND PARTS REPLACEMENT PROCEDURE 26 TROUBLESHOOTING A tana mlt 30 COMPONENT TEST PROCEDURE 2 1 nnnnnnnnnnnnnn nennen nnn hh nnn nnn nini nnne nnn 36 PROCEDURE FOR MEASURING MICROWAVE ENERGY LEAKAGE 42 EXPEODED VIEW AND PARTS LIST estaciona 44 INTRODUCTION nennen nennen nnne nennen nnne nennen enne ens 44 1 DOOR PARTS nennen eene nnne nnne nennen nennen nennen nnne nenne 45 2 CONTROL PANEL PARTS eene 46 OVEN CAVITY PARTS nennen nennen nennen nennen nnne 47 4 OVEN INTERIOR PARTS 1 nnne 48 5 OVEN INTERIOR PARTS 2 menn 49 6 LATCH PARTS nennen innen nnne nnne nennen nnne annee enne nnne nennen 50 7 BASE PLATE PARTS nnne nnne nnne enne nnne nennen annee 51 8 WIRING HARNESS PARTS eene eene 52 9 CIRCUIT BOARD 53 10 CIRCUIT BOARD SCHEMATIC DIAGRAM m 54 REPLACEMENT PARTS LIST as EEE 55 SPECIFICATIONS Power Supply Power Consumption eeeeeneennennnennnnnnnnnn
27. eter should indicate an open circuit When the secondary switch operation is abnormal make the necessary adjustment or replace the switch only with the same type of switch MONITOR SWITCH TEST Isolate the monitor switch by disconnecting it from leadwire Connect the ohmmeter leads to the common COM and normally closed NC terminals of the Switch The meter should indicate a closed circuit in the door open condition When door is closed the meter should indicate an open circuit When the monitor switch operation is abnormal replace 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 25 DISASSEMBLY AND PARTS REPLACEMENT PROCEDURE CAUTION Before touching any oven component or wiring first of all disconnect the power supply cord and wait for about 5 minutes in order to discharge the high voltage capacitor A REMOVING OUTER CASE FIG 14 1 Remove four screws from the side section 2 Remove seven screws from the rear section 3 Push the outer case back about 1 inch 3cm to free it from the front plate 4 Lift the case from the set B REMOVING CONTROL PANEL ASSEM BLY AND PCB ASSEMBLY FIG 15 1 Disconnect the wire leads from relay 3 4 power trans connector 5 pin thermistor con nector 2 pin temperature probe jack connec tor 8 pin and connector 5 pin 2 Remove one screw secu
28. etron tube is the heart of the microwave oven lt is basically a diode with the addition of a magnetic field The magnetron tube assembly con sists of cylindrical cathode negative terminal enclosed within a cylindrical anode positive termi nal evacuated of all air and surrounded by a perma nent magnet In order to create an electron flow from cathode to anode the cathode must be heated and a potential difference must exist between the two This is accomplished by heating the cathode with 3 15 VAC from the filament winding of the high voltage trans former and applying a negative 4000 VDC from the voltage doubler circuit to the cathode Originally the electrons would travel in a straight line from the cathode to the anode see Fig 9 However with the addition of a permanent magnet surrounding the anode creating a magnetic field the electrons travel an orbital path between the cathode and anode see Fig 10 As the electrons approach the anode their orbital path takes them past small resonant cavities that are part of the anode The passing notion of the electrons induces electron cur rent to oscillate in the resonant cavities at the very high frequency or 2 450 megahertz This RF energy is then transferred to the antenna TESTING MAGNETRON TUBE Disconnect power remove the wrapper and dis charge the capacitor Remove the two leads from the magnetron ter minals Connect the ohmmeter between one
29. here is manufacturer s own voluntary standard for units in customer s home EQUIPMENT Electromagnetic energy leakage monitor NARDA 8100B HOLADAY HI 1501 600 cc glass beaker Glass thermometer 100 C or 212 F Fig 42 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 in the center of the oven 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 the probe Operate the oven at its maximum output Measure the microwave radiation using an electromagnetic radiation monitor by holding the probe perpendicular to the surface being measured Move probe along shaded area Probe scanning speed Less than 2 0 cm sec Fig 43 MEASUREMENT WITH THE OUTER CASE REMOVED When you replace the magnetron measure 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 Around the magnetron The waveguide WARNING AVOID CONTACTING ANY HIGH VOLTAGE PARTS 42 MEASUREMENT WITH A FULLY ASSEMBLED OVEN After all components including the outer case are fully asse
30. in the display window Current temperature of oven will be displayed in rising 5 increments If oven temperature is lower than 200 F the display window will show LO F until oven temperature reaches 200 F 12 COMBINATION COOKING 1 Touch COMBINATION HIGH or LOW 2 Touch numbers for desired cooking time 3 Touch START NOTE Output is fixed as follows MICROWAVE CONVECTION COOKING TIME COOKING TIME COMBI HIGH 8 Sec COMBI LOW 8 Sec 14 Sec 375 F 14 Sec 350 F AUTOMATIC DEFROST BY WEIGHT 1 Touch MEAT POULTRY or FISH of AUTO WEIGHT DEFROST 2 Touch numbers for desired weight 3 Touch START NOTE f you input over the acceptable weight E will show in the display window It means error and the oven does not operate When five short beeps sound during Auto Weight Defrost please turn over foods Each category can defrost food with the weight of the defrosting food input The cooking power will automatically be fixed in proportion to the time Categories for Auto Weight Defrost and the maximum weights are 9 9 Ibs AUTOMATIC COMBINATION COOKING 1 Touch AUTO COOK 2 Touch number for desired category 3 Touch numbers for desired cooking weight 4 Touch START NOTE f you input over the acceptable weight E will show in the display window It means error and the oven does not operate When five short beeps sound during cooking please t
31. ing for other trouble 2 Be careful of the high voltage circuit 3 When checking the continuity of the switches or transformer disconnect one lead wire from these parts and then check continuity without turning the power source on 4 Do not touch any part of the circuitry on the control circuit board since electrostatic discharge may damage this control circuit Always touch yourself to ground while working on this circuit to discharge any static charge built up in your body 5 First operate the microwave oven following the correct operating procedures 6 lf the oven becomes inoperative because of a fuse check the primary the secondary and the monitor switches before replacing the fuse TEST PROCEDURE OR CONDITION CAUSE CORRECTION OFF CONDITION The fuse opens when power Shorted wire in power cord Or 7 Replace power cord or check wire harness and repair wire harness Defective monitor switch or out of adjustment Test procedure monitor switch See page 25 0 does not appear in display window when power cord is first plugged into wall outlet Microwave oven plug is not inserted tightly Insert microwave oven plug securely No power at outlet Check home fuse Open fuse Perform fuse test procedure See page 39 Open wire in power cord wiring harness or wiring between control panel assembly unit
32. inside it with a soft damp cloth Check for damage such as misaligned door damage around the door or dents inside the cavity or on the exterior Put the oven on a counter table or shelf that is strong enough to hold the oven and the food and utensils you put in it The control panel side of the oven is the heavy side Use care when handling 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 Make sure the microwave oven legs are in place to ensure proper air flow The oven should not be installed in any area where heat and steam are generated because they may damage the electronic or mechanical parts of the unit Do not install the oven next to a conventional surface unit or above a conventional wall oven Use microwave oven in an ambient temperature less than 104 F 40 C Place the microwave oven on a sturdy and flat surface at least 10 cm 4 inches from the wall Place the microwave oven as far away as possible from TV RADIO COMPUTER etc to prevent interference This oven must be plugged into a 15A outlet Do not touch the front glass during or after cooking of the Grill and Combination mode This glass is very hot during heater operating 10 Do not operate the oven at microwave and combination mode with Grill rack placed in the cavity when the oven is empty EARTHING INSTRUCTIONS This microwave ove
33. mbled 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 NOTES Leakage with the out case removed less than 4 mW cm sq Leakage for a fully assembled oven Before the latch switch primary interrupted with the door in a slightly opened position less than 2 mW cm sq NOTE WHEN MEASURING Do not exceed meter full scale deflection The test probe must be removed no faster than 1 inch sec 2 0 cm sec along the shaded 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 When high leakage is suspected do not move the probe horizontally aiong the oven surface this may possibly cause 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 e Should the microwave energy leakage not be more than 2 mW cm sq after determining that all parts are in good condition
34. moved by pinching the six parts with a wire cutter Fig 20 4 Disconnect the lead wires from the turntable motor terminals 5 Remove two screws securing the turntable motor to the oven cavity assembly 6 Lift the turntable motor V TRANSFORMER H V CAPACITOR BRACKEY Fig 18 7 After repairing the motor rotate the removed turntable motor cover Fig 20 8 Fit the turntable motor cover s projecting part to the base plate s slit Fig 21 NOTE 1 Remove the lead wire from the turntable motor VERY CAREFULLY with long nose pliers 2 Be sure to grasp the connector and not the wires when removing 3 In assembling insert the slit part of turntable motor cover and secure it by using two screws Fig 19 28 Fig 20 Fig 21 1 REMOVING CIRCULATION MOTOR FIG 22 1 Disconnect the wire leads from the circulation motor terminal 2 Remove the screws securing the supporter bracket insulator R and the chamber gross assembly to the oven cavity 3 To remove the chamber gross assembly lift the chamber gross assembly up 4 Remove one hex nut securing the circulation fan to shaft of the circulation motor 5 Remove three screws securing the motor bracket to the chamber 6 Remove two hex nuts securing the circulation motor to the motor bracket J REMOVING CONVECTION HEATER AND THERMISTOR FIG 22 CONVECTION HEATER 1 Follow section 1
35. n is designed to be used in a fully earthed condition It is imperative therefore to make sure it is properly earthed before servicing WARNING THIS APPLIANCE MUST BE EARTHED IMPORTANT The wires in this mains lead are colored in accordance with the following code Green and yellow Earth Blue Neutral Brown Live As the colors of the wires in the mains lead of this appliance may not correspond with the colored markings identifying the terminals in your plug proceed as follows The wire which is colored green and yellow must be connected to the terminal in the plug which is marked with the letter E or by the earth symbol or colored green or green and yellow 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 The wire which is colored brown must be connected to the terminal in the plug which is marked with the letter L or colored red FEATURE DIAGRAM AIR VENTS SEE THROUGH CONTROL PANEL SAFETY INTERLOCK SYSTEM TURNTABLE ROTATING RING ASM CONVECTION RACK Remove your Microwave Convection Oven and all material from the shipping carton Your oven will be packed with the following material Turntable lt 55 nennen 1 Each Rotating Ring ASM 1 Each Convection Rack 1 Each Cookb
36. ntroller when power cord is plugged in As the door is opened the contact of MONITOR SWITCH short This switch creates the short circuit to blow 15 A fuse during operation under abnormal condition i e should the contacts of primary switch and relay and or secondary switch fail to open the circuit WHEN COOKING POWER AND COOKING TIME ARE SET BY TOUCHING THE TIME AND THE POWER PAD The micom controller memorizes the function you set The time or cooking power you set appears in the dispaly window Each indicator light turns on to indicate that stage has been set WHEN TOUCHING THE START PAD WITH THE MICROWAVE FUNCTION SELECTED The oven lamp fan motor and turntable motor oper ate by closing the relay 3 and primary switch The 120 Volts AC is supplied to the high voltage transformer through the contact of the relay 1 and primary switch 3 5 Volt AC generated from the fila ment winding of the high voltage transformer applied to the magnetron to heat magnetron fila ment through two noise suppression chock coils A high voltage 2100 Volts AC is generated in the secondary winding of the high voltage transformer and this secondary voltage is increased by action of the diode and charging of the high voltage capacitor This resultant is then applied to the magnetron via the filament The disturbance wave generated by the magnetron is suppressed by the choke coils filter capacitors and the magnetron shielded case
37. ontinuity COMPONENTS TEST PROCEDURE RESULTS OVEN LAMP SWITCH Wire leads removed Check for continuity of the switch with an Ohm meter Door Door open close NOTE After checking for the continuity of switches make sure that they are correctly connected FAN MOTOR Wire leads removed Measure the resistance Ohm meter scale Rx1 Normal Approx 51 ohm Abnormal Infinite or Several ohms TURNTABLE MOTOR Wire leads removed Measure the resistance Ohm meter scale Rx1000 Normal Approx 2800 ohm Abnormal Infinite or Several ohms CIRCULATION MOTOR Wire leads removed Measure the resistance Ohm meter scale Rx1 Normal Approx 26 ohm Abnormal Infinite or Several ohms COMPONENTS TEST PROCEDURE RESULTS FUSE Check for continuity of the fuse with an Ohm meter Normal Abnormal SESS E MI me Fig 33 NOTE If the fuse is blown check the primary the secondary and the monitor switches before replacing the fuse Refer to Test Procedure Switches on page 25 If the fuse is blown by improper switch operation replace the defective switch and the fuse at the same time Replace just the fuse if the switches operate normally HEATER ELEMENT Measure the resistance Normal Approx 9 3 ohm Wire leads removed Ohm meter scale Rx1 at 20 30 Measure the resistance with 500V 100M Normal more than 0 5
38. ook HH HM 1 Each Owner s lt lt lt lt lt 1 Do not use this Microwave Convection Oven for commercial purposes This Microwave Convection Oven is made for household use only Fig 3 INDICATOR LIGHTS When cooking operations are set lights will go on indicating the cycle in which your oven is cooking CONVECTION Used in setting convection cooking or pre heat REHEAT Used to reheat foods easily Reheat Guides is next to the pad COOK Used to cook foods easily Cook guide is next to the pad MICRO TIME Used in setting microwave cooking time MICRO POWER Used to select cooking power levels CLOCK Used to set the time of day STOP CLEAR Stops the oven and Clears all entries except TIME OF DAY Once cooking has begun however CLEAR will function only after STOP has been touched CONTROL PANEL ENTER POWER lud SENSOR f M fM DE M n vos EE EN Eu EN weicht DEF TEMP START TIME COMBI REHEAT CONVECTION CONTROL solt CONVEC COMBI HIGH COMBI LOW J j a oon BEEF sel LAMB des 1 RARE 4 MEDIUM AUTO COOK Ali 2 MEDIUN 5 WELL DONE c lage
39. oven wall Do not use metallic ware for cooking except where noted in the cookbook Ceramic ware trimmed in gold or silver powder is used Uneven cooking Do not use any type of cookware with metallic trimming Inconsistent intensity of microwave due to their characteristics 1 Wrap the thinner food with aluminum foil 2 Use plastic wrap or with a lid 3 Stir once or twice while cooking soup cocoa Or milk etc Food does not turn during cooking cycle Food or cookware extending oven edges of turntable prevents turning rearrange food Turntable motor does not operate Refer to preceding turntable motor problem CONDITION CAUSE No microwave oscillation TEST PROCEDURE OR CORRECTION Child Lock is set This is not a defect Touch 0 key pad till a beep sounds See page 14 Defective relay 1 of P C B Test procedure relay 1 of P C B See page 40 Defective high voltage transformer Test procedure high voltage transformer See page 36 Defective high voltage capacitor Test procedure high voltage capacitor See page 37 Defective high voltage diode Test procedure high voltage diode See page 36 Defective magnetron Test procedure magnetron See page
40. pacitor 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 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 INSTALLATIONS BEFORE YOU BEGIN READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY INSTALLING 1 Empty the microwave oven and clean
41. rate Check connector and repair wiring Defective relay 4 of P C B Test procedure relay 4 of P C B See page 40 Defective circulation motor Test procedure circulation motor See page 38 Open or loose wiring to the circulation motor Turntable drags or makes noise Check and repair wiring Check receptacles of wire Excessive weight on tray or improperly balanced ee Distribute food evenly cook smaller portions and or use lighter weight cookware CONDITION No input can be programmed Some inputs can not be programmed Display shows a number or figure different from one touched Random programming when pressing other than touch pads Display fixes some figure and can not accept any input Setting time does not count down when touch Start gt CAUSE TEST PROCEDURE OR CORRECTION Defective membrane key of P C B Test procedure membrane key of P C B See page 41 Loose connection Connect them tightly Defective secondary switch or out of adjustment Test procedure secondary switch See page 25 Defective membrane key of P C B Test procedure membrane key of P C B See page 41 Loose connection 32
42. res described in 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 Proper operation of the microwave ovens requires that the magnetron be assembled to the wave guide 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 Routine service safety procedures should be exercised at all times Untrained personnel should not attempt service without a thorough review of the test procedures and safety information contained in this manual TABLE OF CONTENTS SPECIFICATIONS CETT E m 4 CAUTIONS ox cst tatu t cat CE cet ED cs aa aes ts RUN eM te Mode 5 INSTALLATIONS sen as E 6 FEATURE DIAGRAM ee 7 CONTROL PANEL nione det neto ae vetns ausi ctia euenit ea ee 8 HOW THE MICROWAVE CONVECTION OVEN WORKS mnes 10 COOKING EEOW CHART ae ON tM 11 OPERATING INSTRUCTIONS Hr 12 SCHEMATIC DIAGRAM ERE 15 CIRCUIT DESCRIPTION ee me toii ir te cue enean unite decided audae e ted
43. ring the P C B earth wire lead and key pad earth bend to the front plate 3 Remove two screws securing the control panel to the front plate 4 Lift the control panel slightly and remove from the front plate 5 Remove the F P C connector the terminal socket 6 Remove three screws securing the P C B assembly to the control panel NOTE Remove the wire leads and connector VERY CAREFULLY Be sure to grasp the connector and not the wires KEY PAD PCB SUB ASM CONTROL PANEL RELEASE BUTTON Fig 15 C REMOVING DOOR ASSEMBLY FIG 16 1 Remove three tap tite screws securing the V E PLATE hingeplate U to the hinge supporte HING y 2 To remove the door tilt the top of the door DQ towards you and lift the door up gt d 2 NOTES 1 After replacing the door be sure to check that the primary switch monitor switch oven lamp switch and secondary switch operate normally 2 After replacing the door check for microwave energy leakage with a survey meter Refer to the test procedure on page 43 C Fig 16 26 D REMOVING MAGNETRON FIG 17 1 Disconnect the wire leads from the magnetron terminals 2 Remove the two screws holding the air duct to magnetron 3 Remove four screws securing the magnetron to the wave guide NOTE 1 When removing the magnetron make sure its dome does not hit any adjacent parts or it may be damaged 2 When
44. s Replace or repair wiring Display does not operate properly when Clock is touched Defective membrane key of P C B Test procedure membrane key of P C B See page 41 30 CONDITION CAUSE Oven light does not light with door opened TEST PROCEDURE OR CORRECTION No power in home Check wall outlet Open wire in power cord or wire harness Replace or repair wiring Defective oven lamp switch or out of adjustment Test procedure oven lamp switch See page 38 Defective oven light Replace Open or loose wire connection to the above components Check wiring Blown fuse or Oven light Oven light does not light in cook cycle Oven light lights when door is opened COOKING CONDITION Test procedure fuse See page 39 Defective relay 3 of P C B Test procedure relay 3 of P C B See page 40 Defective primary switch or out of adjustment Oven light lights but turntable motor does not operate Test procedure primary switch See page 25 Defective turntable motor Test procedure turntable motor See page 38 Open wiring of turntable motor Turntable motor operates normally but circulation motor does not ope
45. switch Door Door open closed Primary Switch eS 2 Monitor Switch Switch EN PRIMARY INTERLOCK UPPER LATCH SWITCH TEST When the door button is slowly depressed with the door closed an audible click should be heard at the same time or successively at intervals When the button is slowly released 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 adjusted in accordance with adjustment procedure Isolate the primary switch by disconnecting it from leadwire Connect the ohmmeter leads to the common COM and normally open NO terminal of the switch The meter should indicate an open circuit in 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 NOTE After checking for the continuity of switches make sure the wires are correctly connected SECONDARY INTERLOCK LOWER LATCH SWITCH TEST Isolate the secondary switch by disconnecting it from leadwire Connect the ohmmeter leads to the common COM and normally open NO terminals of the switch The meter should indicate a closed circuit in the door open condition When door is closed the m
46. t Nutdriver size 5 mm Adjustable wrench Soldering iron e Solder Vinyl insulation tape Polishing cloth 22 INSTALLATION AND ADJUSTMENT OF THE INTERLOCK SYSTEM A INSTALLATION CAUTION FOR CONTINUED PROTECTION AGAINST RADIATION EMISSION REPLACE ONLY WITH THESE TYPES OF SWITCHES PRIMARY INTERLOCK SWITCH SZM V16 FA 63 or VP 533A OF SECONDARY INTERLOCK SWITCH SZM V01 FA 33 INTERLOCK MONITOR SWITCH SZM V16 FA 62 or VP 532A OF OVEN LAMP SWITCH SZM V6 FA 31 or VP 331A OD The installation of PRIMARY SECONDARY MONI LATCH TOR and OVEN LAMP SWITCH is as shown Fig 13 D PROCEDURE D p amp 5 _ B ADJUSTMENT PROCEDURE TO AVOID POSSIBLE EXPOSURE TO MICRO WAVE ENERGY LEAKAGE THE FOLLOWING ADJUSTMENT OF THE INTERLOCK SWITCHES SHOULD BE MADE ONLY BY AUTHORIZED SERVICE PERSONNEL 1 Loosen the two screws 1 holding the latch board U to the oven cavity front flange 2 With the door closed adjust the latch board by moving it back and forth or up and down 3 Secure the screws firmly 4 Loosen the two screws 3 holding the latch board L to the oven cavity front flange 5 With the door closed adjust the latch board by moving it back and forth or up and down 6 In and out play of the door allowed by the latch board U and L should be less than 0 5 mm 7 Secure the screws firmly FRONT PLATE LATCH BOARD
47. tch board L with monitor switch is activated by latch on the door while the door is closed PRIMARY SWITCH OVEN LAMP SWITCH MONITOR SWITCH SECONDARY SWITCH Fig 11 20 CONVECTION COOKING SYSTEM FIG 12 Convection cooking is not performed by direct heat from the heating elements but by forced circulation of the hot air produced by the heating elements located at the back side of the oven cavity The air heated by the heating elements heater is circulated through the convection chamber of the oven cavity by means of the circulation fan which is driven by the circulation motor Then the hot air enters the inside of oven through the vent holes provided in the back plate of the oven cavity Next the hot air heats up the food on the turn table and leaves the oven cavity through the vent in the centre of the oven cavity back side In a continuous cycle this hot air is reheated by the heater passes through the back chamber convection chamber and enters the inside of the oven cavity again In this way the hot air raises inside air temperature of the oven cavity and thus the food is being cooked Convection heater will heat continuously before the setting tem perature is reached and alternates on and off accord ing to temperature after the setting temperature is reached The on off of the convection heater is controlled by thermistor CONVECTION HEATER CIRCULATION FAN CHAMBER ASSEMBLY FIG 12
48. urn over foods Don t cook with plugging in the temperature probe If you touch Auto Weight Combination Cook key the cooking data input already in each stage is cancelled f you are going to reprogram a certain cooking function after programming Auto Weight Combination data STOP CLEAR must always be touched before Weight can be programmed in pounds and tenths of a pound Categories for Auto Weight Combination Cooking and the maximum weights are 5 9 Ibs REHEAT 1 Touch REHEAT 2 Touch REHEAT repeatedly for desired category of Reheat Touch 1 or 2 3 Touch START NOTE e f you touch Reheat key the cooking data input already in each stage is cancelled f you reprogram a certain cooking function after programming Reheat data STOP CLEAR must always be touched before HOLD WARM 1 Touch HOLD WARM 2 Touch START NOTE The time of HOLD WARM is 60 minutes With temperature probe foods will be held at 120 F Take care that the temperature probe is not removed from foods ad POPCORN 1 Put a micro proof rack on the turntable 2 Touch POPCORN 3 Touch START NOTE f additional time is required micro HI power in increments of 20 sec Elevate popcorn packages on a micro proof rack Do not leave oven unattended while popping corn This feature can only be used for popping packaged CHILD LOCK To Set Child Lock 1 Touch 0 more than 2 seconds
49. x ZEF HIGH VOLTAGE 20 alg Ios DIODE ns lt O RFP d pre 0 zx lu 5 zo TOMO 6 3 O m Fig 7 16 SYSTEM 3 CONVECTION COOKING CONDITION Set up Door is closed START is touched Normal operation Oven light turns on Turntable operates Fan motor and circulation motor operate THERMOSTAT 2 5 NP gt H co 22 5852 OVEN LAMP Q O lt Q 483 ES TURNTABLE_MOTOR de 2 lt LL FAN MOTOR Q O n z 25 In X CIRCULATION MOTOR gt m o O u y m TEN o 30 T lt w y Se gt 2 zn RECTIFIRE FUSE z Ne O AA ale 9 CONVECTION HEATER e z Ol O z O O ES RELAY E 2 95 1 MONITOR SWITCH I gt gt m lt 2 lt HOLSINHSHL CAN U3SNHOJSNYVHL ADVLIOA HDIH z O sE 4 2I gt Ss e 1 gt Os ZER HIGH VOLTAGE 20 3 DJ m 2m3oo DIODE w lt O GB op RRS SS u lt w e E 5 O 5 A z lt 253 4 pe Fig 8 cs CIRCUIT DESCRIPTION The low voltage transformer supplies the necessary voltage to the micom co
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