Daewoo KOC-971C0S Service Manual
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Daewoo KOC-971C0S Service Manual

Daewoo KOC-971C0S Service Manual

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Service Manual
Microwave Oven
Model: KOC-971C0S
DAEWOO ELECTRONICS CO., LTD.
S/M No. : R981C0S001
KOC-971C2S
KOC-981C1S
KOC-981C2S

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Summary of Contents for Daewoo KOC-971C0S

  • Page 1 S/M No. : R981C0S001 Service Manual Microwave Oven Model: KOC-971C0S KOC-971C2S KOC-981C1S KOC-981C2S DAEWOO ELECTRONICS CO., LTD.
  • Page 2 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 w ith the door open. (b) M ake the following safety checks on all ovens to be serviced before activating the m agnetron or other m icrowave source, and m ake repairs as necessary: (1) Interlock operation, (2) Proper door closing, (3) S eal and sealing surfaces (arcing, wear, and other dam age), (4) Dam age to or loosening of hinges and latches, (5) Evidence of dropping or abuse.

  • Page 3: Safety And Precautions

    SAFETY AND PRECAUTIONS 1. FOR SAFE OPERATION Damage that allows the microwave energy (that cooks or heats the food) to escape will result in poor cooking and may cause serious bodily injury to the operator. IF ANY OF THE FOLLOWING CONDITIONS EXIST, OPERATOR MUST NOT USE THE APPLIANCE. (Only a trained service personnel should make repairs.) (1) A broken door hinge.

  • Page 4: Specifications Are Subject To Change Without Notice

    SPECIFICATIONS M O D E L K O C-971C0S KO C -971C 2S P O W E R SU P P LY 230V ~50H z 230V ~50Hz M IC R O W AV E 1450W 1450W G R ILL 1200W 1200W CO N V EC T IO N 1550W...

  • Page 5: External View

    EXTERNAL VIEW 1. OUTER DIMENSION KOC-971C KOC-981C...

  • Page 6: Feature Diagram

    EXTERNAL VIEW 2. FEATURE DIAGRAM KOC-971C 1. Door seal - Door seal maintains the microwave energy within the oven cavity and prevents microwave leakage. 2. Door hook - When the door is closed, it will automatically shut. If the door is opened while the oven is operating, the magnetron will immediately stop operating.
  • Page 7 EXTERNAL VIEW KOC-981C 1. Door seal - Door seal maintains the microwave energy within the oven cavity and prevents microwave leakage. 2. Door hook - When the door is closed, it will automatically shut. If the door is opened while the oven is operating, the magnetron will immediately stop operating.

  • Page 8: Installation

    This appliance is supplied with cable of special type, which, if damaged, must be repaired with cable of same type. Such a cable can be purchased from DAEWOO and must be installed by a Qualified Person. 6. Examine the oven after unpacking for any damage such as: A misaligned door, broken door or a dent in cavity.

  • Page 9: Control Panel

    CONTROL PANEL When blinking, the oven is When blinking, the oven is operating in "COMBI" operating in "WEIGHT cooking mode. DEFROST" cooking mode. When blinking, the oven is When blinking, the oven is operating in "GRILL" operating in "TIME cooking mode. DEFROST"...

  • Page 10: Disassembly And Assembly

    DISASSEMBLY AND ASSEMBLY Cautions to be observed when trouble shooting. Unlike many other appliances, the microwave oven is high-voltage, high-current equipment. It is completely safety during normal operation. However, carelessness in servicing the oven can result in an electric shock or possible danger from a short circuit. You are asked to observe the following precautions carefully.

  • Page 11: To Remove Cabinet

    DISASSEMBLY AND ASSEMBLY 1. To remove cabinet (1) Remove four screws on cabinet back. (2) Push the cabinet backward. 2. To remove guide wind assembly (1) Remove two screws for earthing and for fixing to rear-plate. (2) Remove the noise filter from the guide wind. (3) Pull the fan from the motor shaft.

  • Page 12: To Remove H.v.transformer

    DISASSEMBLY AND ASSEMBLY 3. To remove H.V.transformer (1) Remove four screws which secure the H.V.transformer to the base plate. (2) Remove the H.V.transformer. (3) Reverse the above steps for reassembly. 4. To remove high voltage capacitor (1) Remove a screw which secure the grounding ring terminal of the H.V.

  • Page 13: To Remove Magnetron

    DISASSEMBLY AND ASSEMBLY 5. To remove magnetron (1) Remove three screws which secure the magnetron. (2) Remove the magnetron. (3) Reverse the above steps for reassembly. CAUTION N ever install the m agnetron w ithout the m etallic gasket plate which is packed w ith each m agnetron to prevent m icrow ave leakage.

  • Page 14: To Remove Control Panel Assembly

    DISASSEMBLY AND ASSEMBLY 6. To remove control panel assembly (1) Remove a screw which secure the control panel assembly to the oven front plate. At the same time, draw forward the control panel assembly from the oven front plate. (2) Disconnect membrane tail from the connector of the PCB main assembly.

  • Page 15: To Remove Door Assembly

    DISASSEMBLY AND ASSEMBLY 7. To remove door assembly (1) Remove two screws which secure the stopper hinge top. (2) Remove the door assembly from top plate of cavity. (3) Reverse the above steps for reassembly. NOTE A fter replacing the door assem bly, perform a check of correct alignm ent with the hinge and cavity front plate.

  • Page 16: Method To Reduce The Gap Between The Door Seal And The Oven Front Surface

    DISASSEMBLY AND ASSEMBLY 9. Method to reduce the gap between the door seal and the oven front surface. (1) To reduce gap located on part ‘A’ • Loosen two screws on stopper hinge top, and then push the door to contact the door seal to oven front surface. •...

  • Page 17: To Remove Motor Syncro And Under Heater

    DISASSEMBLY AND ASSEMBLY 10. To remove motor syncro and under heater (1) Cut the syncro motor cover parts from the base plate. (2) Remove two screws which secure the motor syncro and supporter to bracket syncro motor. (3) Remove two screws and under heater assembly in cavity 11.
  • Page 18 DISASSEMBLY AND ASSEMBLY KOC-981C (1) Remove two screws which secure the cover insulator *t to top plate. (2) Remove the harness between heaters. (3) Remove two screws for removing heater brackets. (4) Remove heaters. (5) Reverse the above steps for reassembly. 12.

  • Page 19: Interlock Mechanism And Adjustment

    INTERLOCK MECHANISM AND ADJUSTMENT The door lock mechanism is a device which has been specially designed to completely eliminate microwave radiation when the door is opened during operation, and thus to perfectly prevent the danger resulting from the leakage of microwave. 1.

  • Page 20: Troubleshooting 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 then check continuity with the AC plug removed.
  • Page 21 TROUBLE SHOOTING GUIDE CON DITION CHECK RESULT CAUSE REM EDY R eplace C heck con tinuity of D efective O utlet has m agn etron C ontinuity m agn etron proper voltage Fuse does not blow. R eplace D efective C heck con tinuity of noise C ontinuity noise filter board...
  • Page 22 TROUBLE SHOOTING GUIDE (TROUBLE 3) No microwave oscillation even though fan motor rotates. CON DITION CHECK RESULT CAUSE REM EDY N o m icrowave C heck continuity of high oscillation Continuity voltage fuse R eplace high voltage fuse Replace Continuity Defective C heck continuity of high high voltage...
  • Page 23 TROUBLE SHOOTING GUIDE (TROUBLE 4) Display shows all figures selected, but oven does not start cooking, even though desired program and time are set and start pad is tapped. CON DITION CHECK RESULT CAUSE REM EDY A djus t or C heck con tinuity of M alfunction Turn table...
  • Page 24 TROUBLE SHOOTING GUIDE (TROUBLE 6) The following visual conditions indicate a probable defective touch control circuit or button P.C.B. assembly. 1. Incomplete segments (1) Segments missing (2) Partial segments missing (3) Digit flickering other than normal fluorescent slight flickering (4) 0 does not display when power is on. 2.
  • Page 25 TROUBLE SHOOTING GUIDE MEMBRANE KEYBOARD CHECK PROCEDURE 1. Check the pad termination order and nomenclature.
  • Page 26 TROUBLE SHOOTING GUIDE 2. Type of button names (key Matrix and circuit diagram) The membrane keyboard consists of 14 keys whose configurations are described above and provides 8 pad terminations to be connected to the touch control circuit as in above. 3.

  • Page 27: 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 wit the microwave oven supplied at rated voltage and operated at its maximum microwave power setting with a load of 1000 ±...

  • Page 28: Electrical Continuity Check Of Interlock Switch

    MEASUREMENT AND TEST 2. ELECTRICAL CONTINUITY CHECK OF INTERLOCK SWITCH NOTE R em ove the pow er plug from the w all receptacle before testing. PROCEDURE 1. Primary interlock switch (1) Disconnect two connectors from primary interlock switch. (2) Connect the ohm-meter leads between the terminals of the primary interlock switch. 2.

  • Page 29: Microwave Radiation Test

    MEASUREMENT AND TEST 3. MICROWAVE RADIATION TEST WARNING M ake sure to check the m icrow ave leakage before and after repair of adjustm ent. A lw ays start m easuring of an unknow n field to assure safety for operating personnel from m icrow ave energy. D o not place your hands into any suspected m icrow ave radiation field unless the safe density level is know n.

  • Page 30: Component Test Procedure

    MEASUREMENT AND TEST 4. COMPONENT TEST PROCEDURE • High voltage is present at the high voltage terminal of the high voltage transformer during any cooking cycle. • It is neither necessary nor advisable to attempt measurement of the high voltage. •...

  • Page 31: Wiring Diagram

    WIRING DIAGRAM...

  • Page 32: Schematic Diagram

    SCHEMATIC DIAGRAM *KOC-971C *KOC-981C *KOC-971C *KOC-981C...
  • Page 33 SCHEMATIC DIAGRAM * KOC-971C : * KOC-981C : * KOC-971C * KOC-981C...
  • Page 34 SCHEMATIC DIAGRAM * KO C-971C : * KO C-981C :...

  • Page 35: Exploded Views And Parts List

    EXPLODED VIEWS AND PARTS LIST 1. KOC-971C EXPLODED VIEW...
  • Page 36 EXPLODED VIEWS AND PARTS LIST PARTS LIST REF NO. PAR T CODE PART NAM E DES CRIPTION Q TY REMA RK A 00 3511708300 D O O R A S K O C -971C P K CP S W Q 180 C O NT R O L-PAN E L AS KO C -971C 0S B 00...
  • Page 37 EXPLODED VIEWS AND PARTS LIST REF NO. PAR T CODE PART NAM E DES CRIPTION Q TY REMA RK F 35 3513002900 H O LD E R H E AT E E R B RA S S C3604B D F 36 7391800011 N UT H E X 6N -1-8 M F Z N...
  • Page 38 EXPLODED VIEWS AND PARTS LIST 2. KOC-981C EXPLODED VIEW...
  • Page 39 EXPLODED VIEWS AND PARTS LIST PARTS LIST REF NO. PART C ODE PART NAM E DESC RIPTION RE MARK A 00 3511708300 D O O R A S K O C -981C P K C P SW Q 150 C O NT R O L-PA N E L AS K O C -981C (SIM U LTA N E O U S ) B 00 P K C P SW Q 150...
  • Page 40 EXPLODED VIEWS AND PARTS LIST REF NO. PART C ODE PART NAM E DESC RIPTION RE MARK F 38 3512765100 H AR N E S S H E AT E R #187 F LA G 65M M F 39 3517302500 FO A M CR 10T *180*30 F 40...

  • Page 41: Printed Wiring Board

    PRINTED WIRING BOARD 1. CIRCUIT CHECK PROCEDURE 1. Low Voltage Transformer check • The low voltage transformer is located on the P.C.B. • Measuring condition (input voltage) : 230 VAC / 50 Hz KOC-971C/981C L.V.T. : DMR -101FS Term inal Voltage 1 - 2 230VAC /50Hz...
  • Page 42 PRINTED WIRING BOARD 3. Display Problems CA USE MEASUREME NT RESULT R EMEDY Poor contact betw een C heck the voltage of display pin 1 & F ix the pin 1 & P.C .B . and display 2.6 VAC 25 on the P.C .B. filam ent The display has som e R efer to T he display trouble...
  • Page 43 PRINTED WIRING BOARD 4. Case of no microwave oscillation (1) Situation : When touching M/W pad, oven lamp turns on, fan motor and turntable motor rotate and cook indicator in the display comes on. • CAUSE : Relay 2 (RY2) does not operate. KOC-971C/981C 1N4148 •...
  • Page 44 PRINTED WIRING BOARD • Check method STAGE POINT A POINT B RE LAY O N +5 VD C G N D RE LAY O F F G N D +12 V DC 5. Case of no heating of upper heater When touching TEMP COOK &...
  • Page 45 PRINTED WIRING BOARD 7. Case of no stopping of the count down timer When the door is opened during operation, the count down timer does not stop. KOC-971C/981C • Check method STAGE POIN T A POINT B D oor opened O pen +5 V DC D oor closed...

  • Page 46: Circuit Diagram

    P.C.B. CIRCUIT DIAGRAM...
  • Page 47 P.C.B. CIRCUIT DIAGRAM PCB ASS’Y PART LIST Q ′ ′ ′ ′ TY NAM E SYMBOL SPECIFCATION PART CODE P CB M 206-2 94X 181 3514312652-3 T RA N S PO W E R LV T 1 DM R -101F S 5EP V 041401 H O LD E R V F D D PH...

This manual is also suitable for:

Koc-971c2sKoc-981c1sKoc-981c2s

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