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Daewoo KOT-170U0A Service Manual

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Service Manual
Microwave Oven
Model: KOT-170U0A
KOT-170S0A
KOT-174S0A
KOT-175S0A
DAEWOO ELECTRONICS CO., LTD.
http : //svc.dwe.co.kr
S/M No. : T170U0A002
Mar. 2002

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Summary of Contents for Daewoo KOT-170U0A

  • Page 1 S/M No. : T170U0A002 Service Manual Microwave Oven Model: KOT-170U0A KOT-170S0A KOT-174S0A KOT-175S0A DAEWOO ELECTRONICS CO., LTD. http : //svc.dwe.co.kr Mar. 2002...

  • 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 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.

  • Page 3: Safety And Precautions

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

  • Page 4: Specifications

    SPECIFICATIONS Model KOT-170U, KOT-170S, KOT-174S, KOT-175S Power Supply 120V ~ 60 Hz Rated Current 15A (microwave oven only). Power Consumption 1700W, Max. Microwave Output Power (IEC 705) 1100W Frequency 2450 MHz ±50 MHz Outside Dimensions (WxHxD) 760x427x381 mm Cavity Dimensions (WxHxD) 506x256.5x348 mm Net Weight 24.5Kg...

  • Page 5: External View

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

  • Page 6: Disassembly And Assembly

    DISASSEMBLY AND ASSEMBLY Caution to be observed when trouble shooting Unlike many other appliances, the microwave 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 CN2. b) 2-Pin connector on relay RY1. c) 3-Pin connector at CN5. d) 6-Pin connector at CN4. e) 6-Pin connector at CN3 (Only sensor type model). f) Lift the end of the locking arm on the ribbon cable at CN1, then lift the ribbon cable out of the socket.
  • 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 shock or other per- sonal 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 : Persona 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 : Persona 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 could result in electrical shock or other personal injury. -REPLACING A SWITCH FIG. 7 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. 12 for the following steps: FIG. 12 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 FIG. 13-1 FIG. 13-2...
  • Page 23 13. REPLACING THE VENTILATION MOTOR FIG. 14 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 24 14. REPLACING THE FAN 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 25 15. PEPLACING 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 26 16. REPLACING THE HIGH-VOLTAGE TRANSFORMER WARNING : Personal Injury Hazard Disconect 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 3. Discharge the high-voltage capacitor. 4. Remove 4 screws from the H.V. Transformer and save the screws. Refer to FIG. 17-1 for the following steps: 5. Unplug the five high-voltage transformer wire connectors and remove high voltage transformer. 6. Mount the new high-voltage transformer to the plate with 4 mounting screws you removed earlier. 7.
  • Page 28 17. 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 29 18. 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 30 7. Position the new high-voltage capacitor with the round blister (between the leads). Make sure that the flange on the strap is against the front end of the capacitor, and tighten the screw just enough to hold the capacitor in place. 8.
  • Page 31 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 32 9. Mount the magnetron cover lamp to the new magnetron with its 1 mounting screw. 10. Position the new magnetron so that the magnetron the cover lamp the front of the oven, and mount the magnetron to the top of the chassis with its four mounting hex unts. Make sure that you tighten the nuts securely. 11.

  • Page 33: Trouble Shooting Guide

    TROUBLE SHOOTING GUIDE Following the procedure 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 34 CONDITION CHECK RESULT CAUSE REMEDY Replace Defective mag- Outlet has Check continuity of magnetron Continuity netron proper volt- age Fuse does not Replace blow. Open power sup- Check continuity of Continuity power supply cord ply cord Replace Normal Defective touch control circuit Replace Display do not shown...

  • Page 35: 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 36 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 37 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 38 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 39 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 40 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 41 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 gradual- across the capacitor terminals. ly returns to infinity. b) Abnormal - The meter indicates infin- ity, or zero ohms (a short) immediately.

  • Page 42: Wiring Diagram

    WIRING DIAGRAM 1. WIRING DIAGRAM...
  • Page 43 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 44 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 45 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 46: Printed Circuit Board

    PRINTED CIRCUIT BOARD 1. CIRCUIT CHECK PROCEDURE 1) Low Voltage Transformer (DMR-210P) Check The low voltage transformer is located on the PCB Measuring condition : Input voltage : 120 V Frequency : 60Hz Voltage LOAD NO LOAD Terminal 6 - 7 AC 17V AC 20V 8 - 10...
  • Page 47 3) Display problems CAUSE MEASUREMENT RESULT REMEDY Poor contact between PCB Check the voltage of PIN 1, 2 2.6 VAC Fix the PIN 1,2 & and display filament & PIN 32, 33 32, 33 on the PCB Defective display Refer to the display trouble Replace PCB shooting data below.
  • Page 48 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 6 does not operate. - CHECK METHOD STAGE POINT RELAY 6 ON +5VDC...
  • Page 49 5)When the door is opened during operation, the Count down timer does not stop. - CHECK METHOD STAGE POINT 1) DOOR OPEN OPEN +5VDC 2) DOOR CLOSED CLOSED CHECK NO. Check the stage (ON, OFF) of the secondary interlock Replace secondary interlock switch. switch by resistance measurement.
  • Page 50 6) When Er01 & Er03 come on display. -CHECK METHOD In AUTO REHEATING just operating. checking point A, B, C, & D after 1~2 minutes. CHECK POINT REMARK Tolerance 0.5V≤VALUE≤3.5V – 11.3Vdc ±5% 4.4Vdc ±5% 2.2Vdc ±5% R 6~10 & connecting status of humidity sensor must be checked before checking point A, B, C & D. * The Method of connecting humidity sensor * IC2(LM358)
  • Page 51 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 52 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. MEMBRANE KEYBOARD CHECK PROCEDURE 1. Check the pad termination order and nomenclature KOT-170S0A/KOT-174S0A/KOT-175S0A KOT-170U0A...
  • Page 53 2. Type of encoding and pad names The membrane keyboard consists of 33 keys whose configurations are described above and provide 12 pad termintions to be connected to the touch control circuit. 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.
  • Page 54 20) POPCORN pad : Between F and J 21) BEVERAGE pad : Between G and J 22) START pad : Between A and K 23) FAVORITE CHOICE pad : Between B and K 24) TURNTABLE ON/OFF pad : Between C and K 25) CLOCK/AUTO START pad : Between D and K 26) AUTO DEFROST...
  • Page 55 2. COMPONENT INFORMATION 2. COMPONENT INFORMATION 1) TRANSISTOR 1) TRANSISTOR 2) DIODE AND ZENER DIODE...
  • Page 56 3. PRINTED CIRCUIT BOARD FILM...
  • Page 58 4. PCB CIRCUIT DIAGRAM...
  • Page 59 5. PCB LOCATION NO NAME SYMBOL SPECIFCATION PART CODE Q’TY REMARK BUZZER BM-20K 3515600100 CAPACITOR ARRAY 6P(5) 102 M 50V CN5XB-102M CAPACITOR CERAMIC C1, C2, C7, C8, 104 50V Z AXIAL CCZF1H104Z C10~13 CAPACITOR CERAMIC 102 50V Z AXIAL CCZB1H102K KOT-170S CAPACITOR CERAMIC C4, C5, C6, C9...
  • Page 60 NAME SYMBOL SPECIFCATION PART CODE Q’TY REMARK RESISTOR METAL FILM R17 1/6W 357K Ohm 1% RN-AZ3573F KOT-170S RESISTOR CARBON FILM R19 1/6W 100K Ohm 5% RD-AZ104J- RESISTOR CARBON FILM R22 1/6W 4.7K Ohm 5% RD-AZ472J- RESISTOR CARBON FILM R23 1/2W 270 Ohm 5% RD-2Z271JS RESISTOR CARBON FILM R25 1/4W 1K Ohm 5%...

  • Page 61: Exploded View And Parts List

    EXPLODED VIEW AND PARTS LIST 1. DOOR ASSEMBLY 1) KOT-170U0A, KOT-170S0A REF. NO. PART NAME DESCRIPTION PART CODE Q’TY REMARK BLACK FRAME DOOR 3512205000 BISQUE WHITE BLACK HANDLE DOOR *O 3512603800 BISQUE WHITE 3517007200 BLACK BARRIER SCREEN *O TEMP GLASS T3.2...
  • Page 62 2) KOT-174S0A REF. NO. PART NAME DESCRIPTION PART CODE Q’TY REMARK FRAME DOOR 3512205000 BLACK HANDLE DOOR *O 3512603800 BLACK BARRIER SCREEN *O TEMP GLASS T2.8 3517007220 BLACK HANDLE DOOR *I 3512603900 BLACK DOOR PAINTING AS KOT-150S0A 3511712300 BLACK HOOK 3513101200 SPRING HOOK 3515101800...
  • Page 63 4) KOT-175S0A REF. NO. PART NAME DESCRIPTION PART CODE Q’TY REMARK BLACK FRAME DOOR 3512204430 BISQUE WHITE BLACK HANDLE DOOR 3512604400 BISQUE WHITE BLACK BARRIER SCREEN *O TEMP GLASS T3.2 3517006280 BISQUE WHITE BLACK SUPPORTER HANDLE 3515307910 BISQUE WHITE BLACK DOOR PAINTING AS KOT-150S0A 3511712300...
  • Page 64 2. CONTROL PANEL ASSEMBLY 1) KOT-170U0A, KOT-170S0A, KOT-174S0A REF. NO. PART NAME DESCRIPTION PART CODE Q’TY REMARK BLACK KOT-170U0A 3518522600 BISQUE WHITE SWITCH MEMBRANE BLACK KOT-170S0A 3518522610 BISQUE WHITE KOT-174S0A 3518522610 BLACK BLACK KOT-170U0A CONTROL PANEL 3516725900 BISQUE KOT-170S0A WHITE BACK PLATE SECC T0.6...
  • Page 65 1) KOT-175S0A REF. NO. PART NAME DESCRIPTION PART CODE Q’TY REMARK BLACK SWITCH MEMBRANE KOT-175S0A 3518522620 BISQUE WHITE DECORATOR C-PANEL STS430 T0.5 3511609200 BLACK CONTROL PANEL 3516722730 BISQUE WHITE BACK PLATE SECC T0.6 3516802110 KOT-155S0A PCB AS KOT-175S0A PKMPMSAE10 SCREW TAPPING T2S TRS 4X12 MFZN 7122401211...
  • Page 66 3. TOTAL ASSEMBLY...
  • Page 67 REF. NO. PART NAME DESCRIPTION PART CODE Q’TY REMARK BLACK KOT-170U0A, 170S0A 3511715800 BISQUE WHITE BLACK DOOR AS KOT-174S0A 3511715810 BISQUE WHITE BLACK KOT-175S0A 3511712250 BISQUE WHITE BLACK KOT-170U0A PKCPSWAE00 BISQUE WHITE BLACK KOT-170S0A PKCPSWAE10 BISQUE CONTROL PANEL ASSY WHITE...
  • Page 68 SBHG T0.8 3515306900 SCREW SPECIAL T1 TRS 4X16 SE MFZN 7S312X40D1 NUT HEX NUT FLANGE M5X0.8P MFZN 7S627W50X1 MOTOR VENTILATON OBB-2232X1 3964821900 KOT-170U0A 3516112500 170U CAVITY AS KOT-170S0A 3516112510 170S, 174S only GUIDE TRAY RACK POLYSULFONE 3512515900 COVER WAVE GUIDE...
  • Page 69 GUIDE AIR *T PP TB53 8512521500 MOTOR SHADED POLE 120V 60HZ MW15XA-P03 3963822500 SCREW TAPPING T2S PAN 4X30 MFZN 7121403011 HARNESS THERMOSTAT KOT-170U0A 3512767300 BLACK CABINET PCM OR PAINTED STEEL 3510802900 BISQUE WHITE SCREW TAPPING TI TRS 4X10 MFZN BK...
  • Page 70 DAEWOO ELECTRONICS CO., LTD. 686, AHYEON-DONG MAPO-GU SEOUL, KOREA C.P.O. BOX 8003 SEOUL, KOREA TELEX: DWELEC K28177-8 CABLE: “DAEWOOELEC” S/M NO. : T170U0A002 PRINTED DATE: Mar, 2002...

This manual is also suitable for:

Kot-170s0aKot-174s0aKot-175s0a

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