Daewoo KOT-1G1A Service Manual
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Daewoo KOT-1G1A Service Manual

Daewoo KOT-1G1A Service Manual

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S/M No. :
Service Manual
Microwave Oven
Model: KOT-1G1A
MCO165UW/UB
Caution
: In this Manual, some parts can be changed for improving,
their performance without notice in the parts list. So, if you
need the latest parts information, please refer to PPL(Parts
Price List) in Service Information Center (http://svc.dwe.co.kr).
May. 2009

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Summary of Contents for Daewoo KOT-1G1A

  • Page 1 S/M No. : Service Manual Microwave Oven Model: KOT-1G1A MCO165UW/UB Caution : In this Manual, some parts can be changed for improving, their performance without notice in the parts list. So, if you need the latest parts information, please refer to PPL(Parts Price List) in Service Information Center (http://svc.dwe.co.kr).

  • Page 2: Table Of Contents

    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 micro- wave source, and make repairs if 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.

  • Page 3: Proper Use And Service Precautions

    PROPER USE AND SERVICE PRECAUTIONS CAUTION : This Device is to be Serviced Only by Properly Qualified Service Personnel. Consult the Service Manual for Proper Service Procedures to Assure Cotinued Safey Operation and for Precautions to be Taken to Avoid Possible Exposure to Excessive Microwave Energy. 1.

  • Page 4: Specifications

    SPECIFICATIONS Model KOT-1G1A Power Supply 120V ~ 60 Hz, SINGLE PHASE WITH GROUNDING Rated Current Power Consumption 1600W, Max. Microwave Output Power (IEC 705) 1000W Frequency 2450 MHz Outside Dimensions (WxHxD) 760x427x373 mm ( 29.9" x 16.8" x 14.7" ) Cavity Dimensions (WxHxD) 514x248x347 mm ( 20.2"...

  • Page 5: External View

    EXTERNAL VIEW ; REFER TO THE INSTALLATION GUIDE INSTALLATION ; REFER TO THE INSTALLATION GUIDE OPERATIONS AND FUNCTIONS ; REFER TO THE USE AND CARE MANUAL...

  • Page 6: Disassembly And Assembly

    DISASSEMBLY AND ASSEMBLY Caution to be observed when trouble shooting Unlike many ther applicances, the microvave oven is high-voltage, high-current equipment. It is completely safe during normal operation. However, carelessness is servicing the oven can result in an electronic shock or possible danger from a short circuit.
  • Page 7 1. GENERAL -REMOVING/REINSTALLING WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. CAUTION : Personal Injury Hazard Because of the weight and size of the microwave oven, two people are required to safely move and install it. Failure to do so could result in personal injury.
  • Page 8 FIG. 1...
  • Page 9 2.THE OPERATING CONTROL SYSTEMS -REPLACING THE CONTROL CIRCUIT BOARD WARNING : 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. 1.
  • Page 10 4. Unplug the following connectors from the control circuit board: a) 2-Pin connector at CN1. b) 2-Pin connector on relay RY1. c) 7-Pin connector at CN3. d) Lift the end of the locking arm on the ribbon cable at CN2, then lift the ribbon cable out of the socket. 5.
  • Page 11 3. REPLACING AN OVEN LIGHT SOCKET WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. 1. Remove the screws for the vent grille and remove the grille.(See FIG.1) 2.
  • Page 12 4. REPLACING THE LINE FUSE WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. 1. Remove 2 screws from the vent grille and remove the grille (See FIG. 1). 2.
  • Page 13 5. REPLACING THE VENT MOTOR CAPACITOR WARNING : Personal Injury Hazard Disconnect from the electrical supply before srvicing the unit. Failure to do so could result shock or other personal injury. CAUTION : Personal Injury Hazard Because of the weight and size of the microwave oven, two people are required to safely move and install it. Failure to do so could result in personal injury.
  • Page 14 6. REPLACING/ADJUSTING - INTERLOCK SWITCHES WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so coud result in electrical shock or other personal injury. -REPLACING A SWITCH FIG. 6 1. Disconnect the electrical supply to the microwave oven. 2.
  • Page 15 -MAKING ADJUSTMENTS Refer to FIG. 7-1 for the following steps: 1. If necessary, adjust the interlock switch housing so that the switches operate properly. WARNING : The interlock Monitor Switch provides an added safety check on the Primary and Secondary Interlock Switches. If the Primary and Secondary Interlock Switches allow the oven to operate with the door open, the Monitor Interlock Switch will blow the line fuse.
  • Page 16 7. REPLACING THE THERMOSTAT (BOTTOM/VENT) WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. 1. Disconnect the electric supply to the microwave oven. 2.
  • Page 17 8. REPLACING THE TRAY MOTOR WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. CAUTION : Personal Injury Hazard Because of the weight and size of the microwave oven, two people are required to safely move and install it. Failure to do so could result in personal injury.
  • Page 18 9. REPLACING A COOK-TOP LIGHT SOCKET WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. CAUTION : Personal Injury Hazard Because of the weight and size of the microwave oven, two people are required to safely move and install it. Failure to do so could result in personal injury.
  • Page 19 10. REPLACING THE DOOR ASSEMBLY WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. CAUTION : Personal Injury Hazard Because of the weight and size of the microwave oven, two people are required to safely move and install it. Failure to do so could result in personal injury.
  • Page 20 11. REPLACING THE GASKET WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. Refer to FIG. 11 for the following steps: FIG. 11 1.
  • Page 21 12. REPLACING -THE CAVITY THERMOSTAT WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. Discharge the high voltage capacitor before working inside the oven. Failure to do so could result in electrical shock.
  • Page 22 13. REPLACING THE VENTILATION MOTOR FIG. 13 CAUTION : Personal Injury Hazard Because of the weight and size of the microwave oven, two people are required to safely move and install it. Failure to do so could result in personal injury. 1.
  • Page 23 14. REPLACING THE POWER CORD WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. CAUTION : Personal Injury Heazard Because of the weight and size of the microwave oven, two people are required to safely move and install it. Failure to do so could result in personal injury.
  • Page 24 15. REPLACING THE HIGH-VOLTAGE TRANSFORMER WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. CAUTION : Personal Injury Hazard Because of the weight and size of the microwave oven, two people are required to safely move and install it. Failure to do so could result in personal injury.
  • Page 25 16. REPLACING THE HIGH VOLTAGE RECTIFER WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. CAUTION : Personal Injury Hazard Because of the weight and size of the microwave oven, two people are required to safely move and install it. Failure to do so could result in personal injury.
  • Page 26 17. REPLACING THE HIGH VOLTAGE CAPACITOR WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. CAUTION : Personal Injury Hazard Because of the weight and size of the microwave oven, two people are required to safely move and install it. Failure to do so could result in personal injury.
  • Page 27 19. REPLACING THE MAGNETRON WARNING : Personal Injury Hazard Disconnect from the electrical supply before servicing the unit. Failure to do so could result in electrical shock or other personal injury. CAUTION : Personal Injury Hazard Because of the weight and size of the microwave oven, two people are required to safely move and install it. Failure to do so could result in personal injury.
  • Page 28 8. Mount the new magnetron with its mounting screw. 9. Reinstall the Air guide top, powercord, case blow fan under, vent motor, the case blow fan top and the vent grille on the microwave. 10. Secure the magnetron thermostat to the magnetron using 2 screws. 11.

  • Page 29: Trouble Shooting Guide

    TROUBLE SHOOTING GUIDE Following the procedures below to check if the oven is defective or not. 1. Check grounding before checking trouble. 2. Be careful of the high voltage circuit. 3. Discharge the high voltage capacitor. 4. When checking the continuity of the switches, fuse or high voltage transformer, disconnect one lead wire from these parts and the check continuity with the AC plug removed.
  • Page 30 CONDITION CHECK RESULT CAUSE REMEDY Replace Defective Outlet has Check continuity of magnetron Continuity magnetron proper volt- Fuse Replace does not Check continuity of Open power blow. Continuity supply cord power supply cord Replace Normal Defective touch control circuit Replace Malfunction of Display do not shown countdown...
  • Page 31 (TROUBLE 3) No microwave oscillation even though vent motor rotates. CONDITION CHECK RESULT CAUSE REMEDY Continuity Replace Check continuity if high Defective high microwave voltage capacitor terminals voltage oscillation with wires removed transformer Continuity in Replace Check continuity of high voltage Defective high backward rectifier in forward and backward...

  • Page 32: Measurement And Test

    MEASUREMENT AND TEST 1. MEASUREMENT OF THE MICROWAVE POWER OUTPUT Microwave output power can be checked by indirectly measuring the temperature rise of a certain amount of water exposed to the microwave as directed below. PROCEDURE 1. Microwave power output measurement is made with the microwave oven supplied at rated voltage and operated at its maximum microwave power setting with a load 1000±...
  • Page 33 2. MICROWAVE RADIATION TEST On every service call, checks for microwave energy emission must be made according to the following manner. 1. Remove the cooking rack from the oven cavity, if the microwave oven is, so equipped. 2. Place 275mL(9. oz.) glass of water in the center of the oven bottom. 3.
  • Page 34 If a microwave oven is found to operate with the door open, report to Department of Service, the manufacturer and CDRH* immediately. Also tell the owner not to use the oven. The interlock monitor switch acts as the final safety switch protecting the customer from microwave radiation. It the interlock monitor switch operates and opens the line fuse, the interlock switches have failed, and you must replace all of them(primary and secondary interlock switches, and the monitor switch), because their contact may be melted and welded together.
  • Page 35 3. COMPONENT TEST PROCEDURE THE THERMOSTAT AND THERMAL CUT OUT There are Two thermostats and Two Thermal Cut Out in the OTR Microwave Oven. They are the cavity thermal cut out and the bottom thermal cut out. The cavity thermal cut out is located air guide top. This thermal cut out is “normally- closed”, and will open at a set temperature to disable the oven.
  • Page 36 VENT MOTOR CAPACITOR the Vent motor capacitor is located directly behind the control panel. It is in use any time the Vent motor is on. The capacitor helps to maintain a constant voltage to the Vent motor so that it runs more efficiently.
  • Page 37 COMPONET TEST PROCEDURE RESULT N. O. and C Terminals a) Normal - The meter Switches (with wire leads removed). All of the switches Set the ohmmeter to the R X 1 indicates infinity. are measured in the same manner. scale, and measure the resistance b) Abnormal - The between the normally-open (N.O.) meter indicates zero...
  • Page 38 COMPONET TEST PROCEDURE RESULT Terminal-To-Terminal a) Normal - The meter High Voltage Capacitor Set the ohmmeter to the Rx10k indicates several scale, and measure the resistance ohms, then gradually across the capacitor terminals. returns to infinity. b) Abnormal - The meter indicates infinity, or zero ohms (a short) immediately.

  • Page 39: Wiring Diagram

    WIRING DIAGRAM 1. WIRING DIAGRAM...
  • Page 40 2. CIRCUIT DESCRIPTION MICROWAVE COOKING - TIME COOKING 1. When the food is placed inside the oven and door is closed. 1) The low voltage transdormer supplies the necessary voltage to the touch control circuit when the power cord is plugged in.
  • Page 41 The Touch control circuit controls the ON-OFF time of RELAY 1 in order to vary the output power of the microwave oven from power level 1 to HI (100%) power. One complete ON and OFF cycle of the RELAY 1 is 29 seconds. The relation between indications on the control panel and the output of the microwave oven is as shown.
  • Page 42 3) Fan motor and turn table stop rotating 4) the oven lamp turns off. 5) As soon as the door is opened, the interlock monitor switch contacts close and creates the short circuit. 6) If the contacts of primary interlock switch malfunction the 20A fuse blows open due to the large current surge caused by the short circuit activation, and this in turn stops magnetron oscillation.

  • Page 43: Printed Circuit Board

    PRINTED CIRCUIT BOARD 1. CIRCUIT CHECK PROCEDURE 1) Low Voltage Transformer (DMR-161P) Check The low voltage transformer is located on the PCB Measuring condition : Input voltage : 120 V Frequency : 60Hz Voltage LOAD NO LOAD Terminal 7 - 8 AC 11V AC 14.5V NOTE :...
  • Page 44 MEASURE POINT 4) When there is no microwave oscillation When touching START pad, oven lamp does not turn on. Fan motor does not rotate, but cook indicator in display comes on. *Cause: RELAY 1,2,4 does not operate. -> refer to Circuit Diagram (point 2,3,4) - CHECK METHOD STAGE POINT RELAY 2,4,5 ON...
  • Page 45 TROUBLE SHOOTING Following the procedures below to check if the oven is defective or not. 1. Check grounding before checking trouble. 2. Be careful of the high voltage circuit. 3. Discharge the high voltage capacitor. 4. When checking the continuity of switches or of the high voltage transformer, disconnect one lead wire from these parts and then check conitnuity with the AC plug removed.
  • Page 46 (TROUBLE 2) Digital readout display does not show programming, even if the membrane keyboard is programmed by touching proper pads. NOTE : Before following the particular steps listed above in the trouble shooting guide for the membrane keyboard, fail- ure, please check for the continuity of each wire-harness between the membrane keyboard and control box assembly.
  • Page 47 3. Key check procedure To determine if the membrane keyboard is defective or not, check the continuity of each pad(key) contacts with a multi- meter. 1) 0 pad : Between A and J 2) 1 pad : Between B and J 3) 2 pad : Between C and J 4) 3...
  • Page 48 2. COMPONENT INFORMATION 2. COMPONENT INFORMATION 1) TRANSISTOR 1) TRANSISTOR KRA106M R1 = 4.7 Kohm Kohm Kohm Kohm 2) DIODE AND ZENER DIODE...
  • Page 49 3. PRINTED CIRCUIT BOARD FILM...
  • Page 50 4. PCB CIRCUIT DIAGRAM...
  • Page 51 5. PCB LOCATION NO NAME SYMBOL SPECIFICATION PART CODE QT'Y REMARK BUZZER BM-20K 3515600100 C ARRAY 7P(6) 1000PF M 50V CN6XB-102M CAPACITOR CERA 102 50V Z AXIAL CCZB1H102K CAPACITOR CERA C1~4,C6,C7 104 50V Z AXIAL CCZF1H104Z CAPACITOR ELEC 50V RS 10uF CEXE1H100A CAPACITOR ELEC 25V RSS 1000MF...

  • Page 52: Exploded View And Parts List

    EXPLODED VIEW AND PARTS LIST 1. DOOR ASSEMBLY (KOT-1G1A) REF NO. PART NAME DESCRIPTION PART CODE Q'TY REMARK DOOR PAINTING AS KOT-150S0A 3511712300 HOOK 3513101200 SPRING HOOK 3515101800 BARRIER-SCREEN *I PE T0.1 3517006300 HANDLE DOOR *O 3512606410 HANDLE DOOR *I...
  • Page 53 2. CONTROL PANEL ASSEMBLY (KOT-1G1A) REF NO. PART NAME DESCRIPTION PART CODE Q'TY REMARK CONTROL-PANEL 3516733780 SWITCH MEMBRANE KOT-1G1A9A 3518572120 BACK-PLATE SECC T0.5 3516802200 PCB MAIN MANUAL AS KOT-1G0A9A PKMPMSF200 SCREW TAPPING T2S TRS 4X12 MFZN 7122401211...
  • Page 54 3. TOTAL ASSEMBLY (KOT-1G1A)
  • Page 55 REF NO. PART NAME DESCRIPTION PART CODE Q'TY REMARK CONTROL-PANEL AS KOT-1G1A9A PKCPSWF250 DOOR AS KOT-1G1A9A 3511726110 CAVITY AS KOT-1G0A9A 3516118200 COVER WAVE GUIDE HEATPROOF PP 3511406200 MOTOR SYNCRO 120V 2W GM-16-12F17 3966820200 SCREW TAPPING T2S PAN 4X6 MFZN 7121400611 COUPLER XAREC 3517400600...
  • Page 56 REF NO. PART NAME DESCRIPTION PART CODE Q'TY REMARK THERMOSTAT OFF:160 ON:115 V #187 3518903800 SCREW TAPPING T2S PAN 3X6 MFZN 7121300611 GUIDE AIR *T 3512526200 THERMOSTAT OFF:100 ON:60 V #187 3518906310 HARNESS THERMOSTAT KOT-1G0A9A 3512782100 COVER CAVITY LAMP SBHG T0.4 3511411800 SCREW TAPPING T2S TRS 4*8 MFZN...
  • Page 57 DAEWOO ELECTRONICS CORP. 1-2, Jeo-dong 1(il)-ga, Jung-gu, Seoul, Korea C.P.O. BOX 8003 SEOUL, KOREA TELEX: DWELEC K28177-8 CABLE: “DAEWOOELEC” S/M NO. : PRINTED DATE: May. 2009...
  • Page 58 ABOUT THIS MANUAL ABOUT THIS MANUAL " " # # $ $ # # % % & & ! ' ' ( ( ) ) * * + + # # " " ) ) , , ! ! # # & & ' ' - - ./ 012 345 6 78 9:;<...

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