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Daewoo KOC-870T0S Service Manual - Disassembly and Assembly

Summary of KOC-870T0S

  • Page 1

    Service manual microwave oven model: koc-870t0s koc-875t0s daewoo electronics co., ltd. S/m no. : c870t0s003 ✔ 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...

  • Page 2

    1 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- w...

  • Page 3

    2 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. ...

  • Page 4: Specifications

    3 model koc-870t0s koc-870t5s power supply 230v ~ , 50hz 240v~, 50hz 230v~, 50hz microwave power consumption 1,550 w 1,550 w 1,550 w output power 900 w (iec 705) 900w(iec 706) 900 w (iec 705) frequency 2,450 mhz 2,450mhz 2,450mhz grill power consumption 1,150 w 1,200 w 1,150 w convection power consu...

  • Page 5: Names and Function of Parts

    4 3 5 6 4 2 1 9 8 8 10 7 11 grill m/w combi +1 min pie temp +10 sec grill combi weight defrost time auto cook pie temp cook kg 1. Roast beef 2. Roast pork 3. Roast chicken 4. Fish fillets 5. Vegetable auto cook time/weight speedy - + clock defrost m/w stop/ clear start 1 door seal - door seal mainta...

  • Page 6: Control Panel

    5 control panel when blinking, the oven is operating in combi cooking. When blinking, the oven is operating in weight defrost. When blinking, the oven is operating in time defrost. When blinking, the oven is operating in weight input mode. Cooking time is increased by 1 minute. Cooking time is incre...

  • Page 7: Operation

    6 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. Open the door - you can restart the oven by closing the door and t...

  • Page 8

    7 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 ho...

  • Page 9

    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 ...

  • Page 10

    9 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 sho...

  • Page 11: Disassembly and Assembly

    10 1. To remove cabinet. (refer to fig. 1) 1) remove three screws on cabinet back. 2) push the cabinet backward. 2. To remove guide wind assembly. (refer to fig. 2) 1) release two screws ¤Ł. 2) remove back-cover ¤Ø . 3) pull the fan ¤º to the motor shaft. 4) release two screws ¤ which secure the mot...

  • Page 12

    11 3. To remove h.V. Transformer. (refer to fig. 3) 1) remove four screws 1 which secure the h.V. Transformer bracket to the base plate. 2) remove the h.V. Transformer 2 . High voltage circuit wiring 2 1 h.V. Trans h.V. Copacitor mognetron h.V.Diode h.V.Fuse.

  • Page 13

    12 4. To remove magnetron. (refer to fig. 4) 1) remove one screws ¤Ł which secure the magnetron ¤ . 2) remove the magnetron. 3) reverse the above steps for reassembly. Caution : never install the magnetron without the metallic gasket plate which is packed with each magnetron to prevent microwave lea...

  • Page 14

    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 the dial knob ¤æ (3) remove nine screws ¤æ which secure the main and sub...

  • Page 15

    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 7 . (2) remove the door seal ass’y 5...

  • Page 16

    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. 3) tighten a screw. (2) to reduce gap located on part...

  • Page 17

    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. 1 2 3 4...

  • Page 18

    17 10. To remove grill heater assembly. (refer to fig. 10) 1) remove the cabinet. 2) release two screws 1 , and remove the top cover 2 . 3) release a screws 3 , and remove air guide outlet 4 . 4) release the above steps for reassembly. Fig. 10 3 4 2 1.

  • Page 19: Trouble Shooting Guide

    18 (trouble 1) oven does not operate at all ; any inputs can not be accepted. Trouble shooting guide condition check result cause remedy fuse blows check continuity of interlock monitor switch with door closed (com ¡Œ nc) check continuity of both primary and secondary interlock switch with door clos...

  • Page 20

    19 (trouble 2) grill heater (top heater) does not heat (food will not become hot). Condition check result cause remedy replace outlet has proper voltage. Fuse does not blow. Check continuitymagnetron no continuity defective magnetron replace check continuity of noise filter board no continuity defec...

  • Page 21

    20 (trouble 3) no microwave oscillation even though fan motor rotates. Condition check result cause defective high voltage transformer remedy no microwave oscillation check continuity of high voltage fuse check continuity of high voltage capacitor terminals with wires removed continuity replace repl...

  • Page 22

    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. (trouble 5) under heater does not heat (food will not become hot). Condition check result cause remedy adjust or replace adjust or replace replace...

  • Page 23

    22 1 1. Incomplete segments, (a) segments missing. (b) partical segments missing. (c) digit flickering other than normal fluorescent slight flickering. (d) ¡ 0 ¡– does not display when power is on. 1 2. A distinct change in the brightness of one or more numbers is the display. 1 3. One or more digit...

  • Page 24

    23 1. Type of encoding and button names. 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. 11. 2. Key check procedure. To determine if the but...

  • Page 25: Measurement

    24 1. Microwave output power 1-1. Standard method 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. 1) microwave power output measurement is made with the microwave oven supplied at rated voltag...

  • Page 26

    25 2-2. Judgement the value of resistance should be applied to the value specified below. 3. Microwave leakage test 3-1. Warning 1) do not place your hands into any suspected microwave leakage field unless the safe density level is known. 2) always start measuring of an unknown field to assure safet...

  • Page 27: Component Test Procedure

    26 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 di...

  • Page 28: Wiring Diagram

    27 wiring diagram.

  • Page 29: Schematic Diagram

    28 idle condition microwave cooking condition schematic diagram.

  • Page 30

    29 grill cooking condition combi cooking condition.

  • Page 31

    30 convection cooking condition.

  • Page 32

    31 exploded views and parts list no name specification part code q'ty 1 cavity as koc-870t0s 3516108630 1 2 rear-plate *0 sbhg-1 t0.6 3516503900 1 3 door as koc-870t0s 3511708840 1 4 control-panel as koc-870t0s pckpswp700 1 koc-870t5s pkcpswp720 1 5 cover wave guide mica to.5 3511403800 1 6 screw ta...

  • Page 33: Printed Wiring Board

    32 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 2) voltage check kmicom pin> display pin check method terminal 1-2 4-5 6-7 8-10 voltage 230.0v 13.0v 35...

  • Page 34

    33 3) display problems the display trouble shooting data. No cause 1 poor contact between p.C.B. And display filament. 2 the display has some trouble in its segment or gril. 3 loss vacumm in the display. Measurement check the voltage of display pin 1 & 25 refer to “the display trouble shooting data”...

  • Page 35

    34 fig. 18 measurement point mp1 mp3 mp2.

  • Page 36

    35.

  • Page 37

    36 4) when there is no microwave oscillation. (1) when touching “m/w” button, oven lamp turns on. Fan motor and turntable motor rotate and cook indicator in display comes on. * cause : relay 3 (ry3) dose not operate. Check method (2) when touching “m/w” button, oven lamp dose not turn on. Turntable ...

  • Page 38

    37 check method 5) when there is not upper heater. When touching “temp cook & combi” button, oven lamp turns on. Fan motor and turntable motor rotate and cook indicator in display comes on. * cause : relay 2 (ry2) dose not operate. Check method 6) when there is not lower heater. When touching “temp ...

  • Page 39

    38 7) when the door is opened during operation, the count down timer does not stop. Check method 8) when “ ” comes on display. Check method if clock does not keep exact time, you must check. Diode d7, transistor q2. Point waveform a b c t: 20ms (60 hz) a ac c 45 b v1 q2 a1266y c4 104 r6 4.7k r4 10k ...

  • Page 40: P.C.B  Curcuit Diagram

    39 p.C.B curcuit diagram 4148 106 106 1266 1266 1266 106 106 106 106 4148 4148 4148 4148 4148 106 106.

  • Page 41: P.C.B. Location No.

    40 p.C.B. Location no. No. Symbol symbol specification part code q’ty remark 1 pcb main m208 92x195 3514314920 1 2 trans power lvt1 dmr-101fs 5epv041351 1 3 holder vfd pp 3513002600 1 4 r carbon film r17 1/4w, 4.7k ohm j rd-4z472j- 1 5 r carbon film r22 1/4w, 100k ohm j rd-4z104j- 1 6 r carbon film ...

  • Page 42

    41 no. Symbol symbol specification part code q’ty remark 38 connector wafer cn4 35328-0610 4cw3061mx0 1 39 tramsostpr q1,q2,q10 kta1266y tzta1266y- 3 40 transistor q3,q4 krc106m tzrc106m-- 2 41 transistor q6,q7,q8,q9,q11 kra106m tzra106m-- 5 42 resonator cr1 cst4.00mgw 5pcst400mg 1 43 ic micom ic1 m...

  • Page 43

    S/m no. : c870t0s003 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) 360-8184 tel: 02) 360-8183 e-mail : g7f00e@web.Dwe.Co.Kr printed date: nov. 1999.