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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.
(c) Before turning on microwave power for any service test or inspection within the microwave generating com-
partments, check the magnetron, wave guide or transmission line, and cavity for proper alignment, integrity,
and connections.
(d) Any defective or misadjusted components in the interlock, monitor, door seal and microwave generation and
transmission systems shall be repaired, replaced, or adjusted by procedures described in this 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.
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Summary of Contents for Daewoo KOC-872T0S
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Page 1: 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 2: Proper Use And Service Precautions
PROPER USE AND SERVICE 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 3: Specifications
SPECIFICATIONS POWER SUPPLY 230V ~ , 50Hz 240V~, 50Hz POWER CONSUMPTION 1,500W 1,550W MICROWAVE OUTPUT POWER 900 W (IEC 705) 900W(IEC 705) FREQUENCY 2,450 MHZ 2,450MHz GRILL POWER CONSUMPTION 1,250 W 1,300W CONVECTION POWER CONSUMPTION 1,650 W 1,700W COMBINATION HEATING POWER CONSUMPTION 2,700 W 2,750W OUTSIDE DIMENSIONS (W X D X H) -
Page 4: Names And Function Of Parts
NAMES AND FUNCTION OF PARTS DEFROST GRILL COMBI WEIGHT TIME TEMP PROGRAM COOK COOK DEFROST GRILL COMBI TEMP PROGRAM COOK 1. ROAST BEEF 2. ROAST PORK 3. ROAST CHICKEN 4. FISH FILLETS 5. VEGETABLE SPEEDY COOK STOP/CLEAR START ¤ DOOR SEAL ƒ¡ Door seal maintains the ¤... -
Page 5: Control Panel
CONTROL PANEL When blinking, the oven is When blinking, the oven is operating in COMBI cooking. operating in WEIGHT DEFROST. When blinking, the oven is operating in GRILL DEFROST When blinking, the oven is GRILL COMBI WEIGHT TIME When blinking, the oven is operating in MIROWAVE operating in TIME DEFROST. -
Page 6: Operation
OPERATION TO STOP THE OVEN WHILE THE OVEN IS OPERATING 1. Press (STOP / CLEAR) button. - The (STOP) indicator starts blinking. - You can restart the oven by touching (START) button. - Touch once more to erase all instruction except clock. 2. -
Page 7: Interlock Mechanism Functions And Adjustments
INTERLOCK MECHANISM FUNCTIONS AND ADJUSTMENTS 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) Primary interlock switch When the door is closed, the hook locks the oven door. - Page 8 (2) Monitor interlock switch When the door is closed, the hook pushes the lever forward, and pushes the Latch Lever downward the lever press the button of the interlock monitor switch to bring it under ‘OFF’ condition. The latch Lever press the button on the secondary interlock switch to bring it under ‘ON’...
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Page 9: Precautions For Disassembly And Repair
PRECAUTIONS FOR DISASSEMBLY AND REPAIR - Cautions 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 in servicing the oven can result in an electric shock or possible danger from a short circuit. -
Page 10: Disassembly And Assembly
DISASSEMBLY AND ASSEMBLY 1. To remove cabinet. (Refer to Fig. 1) 1) Remove four screws on cabinet back. 2) Push the cabinet backward. Fig. 1 2. To remove guide wind assembly. (Refer to Fig. 2) 1) Release two screws ¤Ł . 2) Remove back-cover ¤Ø... - Page 11 3. To remove H.V. transformer. (Refer to Fig. 3) 1) Remove four screws ¤ which secure the H.V. Transformer bracket to the base plate. 2) Remove the H.V. Transformer ¤Ł . Fig. 3 High voltage circuit wiring Mognetron H.V. Copacitor H.V.Diode H.V.
- Page 12 4. To remove magnetron. (Refer to Fig. 4) 1) Remove three screws ¤Ł which secure the magnetron ¤ . 2) Remove the magnetron. 3) Reverse the above steps for reassembly. Fig. 4 CAUTION : Never install the magnetron without the metallic gasket plate which is packed with each magnetron to prevent microwave leakage.
- Page 13 5. To remove control panel assembly. (Refer to Fig. 5, 6) (1) Remove a screw holding control panel assembly to the oven front plate. At the same time, draw forward the control panel assembly from oven front plate. (2) Remove ten screws ¤ , ¤ which secure the main and sub PCB assembly ¤...
- Page 14 6. To remove door assembly. (Refer to Fig. 7) 1) Remove two screws 1 which secure to hinge. 2) Remove door assembly 2. 3) Remove door above for reassembly taking case to replace fixing glue. 7. To remove door part. (Refer to Fig. 8) (1) Remove the Gasket door 8.
- Page 15 8. Method to reduce the gap between the door seal and the oven front surface. (1) To reduce gap located on part ‘A’. 1) Remove the cabinet. 2) Loosen a screw on top door hinge, then push the door to contact the door seal to oven front surface.
- Page 16 9. To remove tray motor and under Heater. (Refer to Fig. 9) 1) Cut the tray motor cover parts from the base plate (Refer to Fig. 9). 2) Remove two screws 7 which secure the tray motor 6 and supporter to tray motor bracket 4 . 3) Remove three screws 1 and under heater assembly 2 in cavity.
- Page 17 10. To remove grill heater assembly. (Refer to Fig. 10) 1) Remove the cabinet. 2) Release hex nut ¤ . 3) Release two hex nuts ¤Œ . 4) Remove Heater bracket ¤º , ¤ and Top Heater Assembly. 5) Remove Top heater Assembly ¤Ø Heater holder ¤Ł . Fig.
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Page 18: Trouble Shooting Guide
TROUBLE SHOOTING GUIDE Following the procedure below to check if the oven is defective or not. 1. Check earthing before trouble checking. 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 check continuity with the AC plug removed. - Page 19 Condition Check Result Cause Remedy Outlet has Check Defective magnetron Replace proper voltage. continuitymagnetron Continuity Fuse does not blow. Check continuity of Defective line filter Replace noise filter board Continuity board Check continuity of Open power supply Adjust. Continuity cord power supply cord Defective touch control Normal...
- Page 20 (TROUBLE 3) No microwave oscillation even though fan motor rotates. Condition Check Result Cause Remedy No microwave Check continuity of oscillation high voltage fuse Continuity Replace high voltage fuse Check continuity of Defective high Replace Continuity high voltage capacitor voltage transformer terminals with wires removed Check continuity of...
- Page 21 (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. Condition Check Result Cause Remedy Turn table motor, and Check continuity Malfunction of Adjust or oven lamp do not turn on of primary Primary interlock...
- Page 22 (TROUBLE 6) The following visual conditions indicate a probable defective touch control circuit or membrance switch assembly 11. Incomplete segments, (A) Segments missing. (B) Partical segments missing. (C) Digit flickering other than normal fluorescent slight flickering. DEFROST ¡ 0:00¡– does not display when power is on. GRILL COMBI WEIGHT TIME 12.
- Page 23 BUTTON KEYBOARD CHECK PROCEDURE 1. Type of encoding and button names. SW101 SW109 SW104 GRILL STOP/ CLEAR SW107 SW108 SW111 AUTO START DEFROST COOK SW102 SW110 SW103 +min COMBI SW106 SW105 SW112 +10sec TEMP CLOCK RA3 RGLD7X104J CA1 B7102M Fig. 11 Key Matrix and circuit diagram The button keyboard consists of 12 keys whose configurations are described above and provides 8 pad terminations to be connected to the touch control circuit as in Fig.
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Page 24: Measurement
MEASUREMENT 1. Microwave Output Power CAUTION : 1-1. Standard Method 1. Water load should be measured exactly to 1 liter. Microwave output power can be checked by indirectly 2. Input power voltage should be exactly volts as measuring the temperature rise of a certain amount of water specified. - Page 25 2-2. Judgement 3-3. Procedures The value of resistance should be applied to the value 1) Prepare 600cc glass or plastic container. specified below. 2) Pour 275¡ 15 milliliters of tap water initially at 68¡ 9 ¢ (20 ¡ 5 ¡ ) in the container. Door Open Closed...
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Page 26: Component Test Procedure
COMPONENT TEST PROCEDURE 1. High voltage is present at the high voltage terminal of the high voltage transformer during any cook cycle. 2. It is neither necessary nor advisable to attempt measurement of the high voltage. 3. Before touching any oven components or wiring, always unplug the oven from its power source and discharge the capacitor (see page 20). -
Page 27: Wiring Diagram
UNDER HEATER TOP HEATER MAGNETRON... -
Page 28: Schematic Diagram
SCHEMATIC DIAGRAM IDLE CONDITION INTERLOCK PRIMARY MONITOR INTERLOCK SWITCH SWITCH (UPPER) H.V. TRANSFORMER COM. H.V. POWER SUPPLY CAPACITOR SINGLE PHASE BK BK WH THERMAL ONLY CUT-OUT H.V. FUSE FUSE LINE FILTER ASS'Y H.V. DIODE COM. RD WH SECONDARY INTERLOCK SWITCH UNDER D.O.M. -
Page 29: Grill Cooking Condition
GRILL COOKING CONDITION INTERLOCK PRIMARY MONITOR INTERLOCK SWITCH SWITCH (UPPER) H.V. TRANSFORMER COM. H.V. POWER SUPPLY CAPACITOR SINGLE PHASE BK BK WH THERMAL ONLY CUT-OUT H.V. FUSE FUSE LINE FILTER ASS'Y H.V. DIODE COM. RD WH SECONDARY INTERLOCK SWITCH UNDER D.O.M. -
Page 30: Convection Cooking Condition
CONVECTION COOKING CONDITION INTERLOCK PRIMARY MONITOR INTERLOCK SWITCH SWITCH (UPPER) H.V. TRANSFORMER COM. H.V. POWER SUPPLY CAPACITOR SINGLE PHASE BK BK WH THERMAL ~ONLY CUT-OUT H.V. FUSE FUSE LINE FILTER ASS'Y H.V. DIODE COM. RD WH SECONDARY INTERLOCK SWITCH UNDER D.O.M. -
Page 31: Exploded Views And Parts List
EXPLODED VIEWS AND PARTS LIST NAME SPEC CODE Q’TY CAVITY AS KOC-871C0S 3516108600 REAR-PLATE *O SBHG-1 T0.6 3516503900 DOOR AS KOC-872T0S 3511708810 CONTROL-PANEL AS KOC-872T0S 3516717810 COVER WAVE GUIDE MICA T0.5 3511403800 SCREW TAPPING T1 BIN 4X8 MFNI 7113400814 BRACKET MOTOR SYNCRO SBHG-1 T0.8... -
Page 33: Printed Wiring Board
PRINTED WIRING BOARD 1.CIRCUIT CHECK PROCEDURE 1) Low voltage transformer (DMR-101FS) check. The low voltage transformer is located on the P.C.B. Measuring condition: Input voltage: 230VAC/50Hz Terminal Voltage 230.0V 13.0V 35.0V 8-10 3.0V NOTE 1 : Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power source voltage. - Page 34 3) Display problems CAUSE MEASUREMENT RESULT REMEDY Poor contact between P.C.B. Check the voltage of display pin 2.6VAC Fix the pin 1 & 25 on and display filament. 1 & 25 the P.C.B. The display has some trouble Refer to “The display trouble shooting Replace P.C.B.
- Page 35 4) When there is no microwave oscillation. (1) When touching “M/W” pad, oven lamp turns on. Fan motor and turntable motor rotate and cook indicator in display comes on. * Cause : Relay 1 (RY1) dose not operate. CHECK METHOD POINT STAGE RY1 “ON”...
- Page 36 CHECK METHOD POINT STAGE RY5 “ON” £«5VDC RY5 “OFF” £«12VDC 5) When there is not upper heater. When touching “TEMP COOK & COMBI” pad, oven lamp turns on. Fan motor and turntable motor rotate and cook indicator in display comes on. * Cause : Relay 2 (RY2) dose not operate.
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Page 37: Board Diagram
7) When the door is opened during operation, the count down timer does not stop. CHECK METHOD CHECK METHOD POINT STAGE Door opened Open +5VDC Doop closed Closed NOTE : Check the state of the secondary interlock switch. 8) When “ ”... - Page 38 1. MAIN PCB(M212)
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Page 39: Circuit Diagram
2. SUB PCB(M213) -
Page 40: Ass'y Parts List
P.C.B CURCUIT DIAGRAM... - Page 41 KOC-872TOS PCB ASS'Y PART LIST NAME SYMBOL SPECIFICATION PART CODE Q'TY M212 93X197 3514314940 M213 84X192 3514314950 TRANS POWER LVT1 DMR-101FS 5EPV041401 HOLDER VFD PP KOR-9930 3513002000 BUZZER BM-20K 3515600100 DIGITRON SVM-5SS13 DSVM5SS13- RESONATOR CERA CST4.00MGW 5PCST400MG IC MICOM MB89143AP-171 141SC871CO R CABON FILM 1/4W, 1K OHM J...
- Page 42 NAME SYMBOL SPECIFICATION PART CODE Q'TY CONNECTOR WAFER 35312-0310 30166M5030 CONNECTOR WAFER 35313-0210 30166M7020 CONNECTOR WAFER 35328-0610 4CW3061MX0 CONNECTOR FILM HLEM15S-1 4CW215SBD0 TRANSISTOR KTA1270Y TZTA1270Y- TRANSISTOR Q2, 3 KTC3198GR TZTC3198GR TRANSISTOR Q4~6, 8, 9 KRC102M TZRC102M-- RELAY RY1, RY2 G5J-1-TP-M-DT-12 5SC0101112 RELAY RY4, RY5...
- Page 43 DAEWOO ELECTRONICS CO., LTD. 686, AHYEON-DONG MAPO-GU SEOUL, KOREA C.P.O. BOX 8003 SEOUL, KOREA TELEX: DWELEC K28177-8 CABLE: “DAEWOOELEC” FAX: 02) 590-6291 TEL: 02) 360-7114/590-6151~5 http://www.dwe.daewoo.co.kr PRINTED DATE: Mar.1998 S/N : C872T0S001...
- Page 44 Service Manual Microwave Oven Model : KOC-872T0S DAEWOO ELECTRONICS CO., LTD. OVERSEAS SERVICE DEPT.