Daewoo KOT-150S0A, KOT-151S0A, KOT-152U0A, KOT-152C0A, KOT-155S0A Service Manual

Service Manual

Microwave Oven

Model: KOT-150S0A

KOT-151S0A

KOT-152U0A

KOT-152C0A

KOT-155S0A

DAEWOO ELECTRONICS CO., LTD.

S/M No. : T150S0A003

http : //svc.dwe.co .kr Feb. 2002

PRECA UTIONS T O BE OBSERVED BEFORE AND DURING SER VICING T O AVOID POSSIBLE EXPOSURE T O EXCESSIVE MICROW AVE 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.

erating compartments, 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 per-

formed on each oven prior to release to the owner.

TABLE OF CONTENTS

PROPER USE AND SERVICE PRECAUTIONS.................................................................................................................2

SPECIFICATIONS...............................................................................................................................................................3

EXTERNAL VIEW................................................................................................................................................................4

INSTALLATION...................................................................................................................................................................4

OPERATIONS AND FUNCTIONS.......................................................................................................................................4

DISASSEMBLY AND ASSEMBLY......................................................................................................................................5

TROUBLE SHOOTING GUIDE .........................................................................................................................................33

MEASUREMENT AND TEST............................................................................................................................................34

WIRING DIAGRAM............................................................................................................................................................42

PRINTED CIRCUIT BOARD..............................................................................................................................................46

EXPLODED VIEW AND PARTS LIST...............................................................................................................................61

PROPER USE AND SERVICE PRECA UTIONS

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.

CAUTION :

Microwave Radiation Personnel Should not Be Exposed to the Microwave Energy Which May Radiate from the Magnetron or Other Microwave Generating device if it is Improperly Used or Connected. All Input and Output Microwave Connections. Wave-Guides, Flanges and Gaskets Must be Secured. Never Operate the Device Without a Microwave Energy Absorbing Load Attached. Never Look Into an Open waveguide or Antenna While the Device is Energized.

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.

2) A broken door viewing screen.

3) A broken front panel, oven cavity.

4) A loosened door lock.

5) A broken door lock. The door gasket plate and oven cavity surface should be kept clean. No grease, soil or spatter should be allowed to build up on these surfaces or inside the oven. DO NOT ATTEMPT TO OPERATE THIS APPLIANCE WITH THE DOOR OPEN. The microwave oven has concealed switches to make sure the power is turned off when the door is opened. Do not attempt to defeat them. DO NOT ATTEMPT TO SERVICE THIS APPLIANCE UNTIL YOU HAVE READ THIS SERVICE MANUAL.

2. FOR SAFE SERVICE PROCEDURES

1) If the oven is operative prior to servicing, a microwave emission check should be performed prior to servicing the oven.

2) If any certified oven unit is found to have excessive emission level 5mW/cm

, the service person should: (a) inform the manufacturer, importer or assembler, (b) repair the unit at no cost to the owner, (c) attempt to ascertain the cause of the excessive leakage, (d) tell the owner of the unit not to use the unit until the oven has been brought into compliance.

3) If the oven operates with the door open, the service person should tell the user not to operate the oven and contact the manufacturer and CDRH immediately.

Model

KOT-150S, KOT-151S, KOT-152U, KOT-152C, KOT-155S

Power Supply 120V ~ 60 Hz Rated Current 14.0 A (microwave oven only).

Power Consumption 1600W, Max.

Microwave Output Power (IEC 705) 1000W

Frequency 2450 MHz ±50 MHz Outside Dimensions (WxHxD) 760x427x375 mm Cavity Dimensions (WxHxD) 492x240x340 mm Net Weight 24.5Kg Timer Digital, 99 min 99sec Power Selections 10 Levels Cavity Volume 1.5 ft

Magnetron cooling Forced air Microwave Distribution Stirring fan disk and turntable Rectification voltage doubler, half-wave. Door Sealing Choke System Safety Device Cavity Thermostat open : 194/90, reset : 32/0

Bottom Thermostat open : 194/90, reset : 32/0 Hood Thermostat open : 104/40, reset : 132.8/56 Line Fuse 20 A Door Interlock Switches Primary Interlock Switch.

Secondary Interlock Switch.

Interlock Monitor. Magnetron type 2M218 High Voltage Capacitor 0.98 2.1KV AC High Voltage Diode 350 mA, 9.0 KV Cook-top Lamp 125V, 30W Cavity Lamp 125V, 30W Tray Glass

* SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE.

SPECIFICATIONS

EXTERNAL VIEW

; REFER TO THE INSTALLATION GUIDE

INSTALLATION

; REFER TO THE INSTALLATION GUIDE

OPERATIONS AND FUNCTIONS

; REFER TO THE USE AND CARE MANUAL

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. You are asked to observe the following precautions carefully.

1. Always remove the power plug from the outlet before servicing.

2. Use an insulated screwdriver and wear rubber gloves when servicing the high voltage side.

3. Discharge the high voltage capacitor before touching any oven components or wiring.

1) Check the grounding. Do not operate on a two-wire extension cord. It is imperative, therefore, make sure it is grounded properly before beginning repair work.

2) Warning about the electric charge in the high voltage capacitor. For about 30 seconds after the operation has stopped an electric charge remains in the high voltage capacitor. When replacing or checking parts, short between oven chassis and the negative high terminal of the high voltage capacitor by using a properly insulated screwdrive to discharge.

4. When the 20A fuse is blown due to the operation for the monitor switch; replace primary interlock switch, secondary interlock switch and interlock monitor switch.

5. After repair or replacement of parts, make sure theat the screws are properly tightened, and all electrical connections art tightened.

6. Do not operate without cabinet.

CAUTION :

Service personnel should remove their watches whenever working close to or replacing the magnetron.

CAUTION :

When servicing the appliance, take a care when touching or replacing high potential parts because of electrical shock or exposing microwave. These parts are as follows-HV Transformer, Magnetron, HV Capacitor, HV Diode.

1. GENERAL

-REMOVING/REINSTALLING

-CABINET

CABINET REMOVAL

Refer to FIG. 1 for the following steps:

1. Remove the microwave oven from its mounting location and set it on a protected (padded) work surface.

2. Remove the two screws from the top of the microwave oven that secure the vent grille to the oven, and pull the top of the vent grille out so the tabs are from their slots, and remove it.

3. Remove 2 screw from the vent motor cover.

4. Remove the remaining 9screws from the top side and rear of the cabinet. Slide the cabinet back and unhook it from the side tabs, then slide the power cord into the cabinet, and lift the cabinet off the oven. Proceed to the section for the component you wish to service.

CABINET INSTALLATION

Refer to FIG. 1 for the following steps:

1. Position the cabinet over the top of the microwave oven and slide the power cord all the way through the top opening.

2. Slide the cabinet forward so that the tabs along the sides of the microwave fit into the corresponding slots in the cabinet.

3. Loosely mount the screws to the top and sides of the cabinet. When all of the screws are installed, tighten them securely.

4. Install the vent grille on the oven with the two long screws.

5. Install the oven in its mounting location.

W ARNING :

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.

FIG. 1

2.THE OPERATING CONTROL SYSTEMS

-REPLACING THE CONTROL CIRCUIT BOARD

1. Remove the two screws from the top of the microwave oven for the vent grille and remove the grille(See FIG. 1).

Refer to FIG. 2, FIG. 2-1 for the following steps:

2. Remove the screw from the front of the microwave oven for wire protector and remove the wire protector(see FIG. 1).

3. Remove the screw from the top center tab of the control panel.

4. From the top and back of the control panel, lift the top locking tab and pull the top of the panel out slightly, then lift the bottom tabs of the panel out of the slots and pull it forward.

W ARNING :

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.

FIG. 2

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.

5. Remove 4 screws from the control circuit board and lift the board off the mounting bracket.

6. Clean the surface of the new display and the inside of the control panel window with a soft, damp cloth to remove any dirt, smudges, or lint.

7. Mount the new control circuit board to the mounting bracket with 4 screws.

8. Plug the following connectors over their control circuit board plugs so that they lock into place: a) 2-Pin connector at CN2. b) 2-Pin connectors 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) Insert the end of the ribbon cable into the narrow slot of connector CN1 as far as it will go(See FIG. 2-2).

Lower the locking arm so that the two small tabs fit into the cutouts of the ribbon cable, then press down so that it locks into place.

9. Mount the control panel to the oven and secure it with its mounting screw.

10. Mount the vent grille to the microwave oven and check out the operation.

FIG. 2-1 FIG. 2-2

3. REPLACING STIRRER MOTOR

1. Remove the vent grille from the microwave oven (See Cabinet Removal for this procedure). Refer to FIG. 3 and the insets for the following steps:

2. Remove the screw from the lamp bracket(stirrer motor cover).

3. Pull the connectors off the stirrer motor terminals.

4. Remove 2 mounting screws from the stirrer motor and remove the motor.

5. Mount the new stirrer motor to the oven with its two mounting screws.

6. Connect the wires to the stirrer motor terminals.

7. Reinstall stirrer motor cover.

8. Refer to Cabinet Installations and reinstall the vent grille on the microwave oven.

W ARNING :

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.

FIG. 3

4. REPLACING AN OVEN LIGHT SOCKET

1. Remove the screws for the vent grille and remove the grille.(See FIG. 1 on page)

2. Remove the screw from cavity lamp bracket and pull out.

3. Remove the socket mounting screw from the cavity lamp bracket.

4. Remove the old light socket, and mount the new socket in its place with its mounting screw.

5. Reattach the wire connectors over the light socket terminals.

6. Reinstall the cavity lamp bracket into its air guide top and secure the cavity lamp bracket with its mounting screw.

7. Mount the vent grille to the microwave oven and check out the operation.

W ARNING :

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.

FIG. 4

5. REPLACING THE LINE FUSE

1. Remove 2 screws from the vent grille and remove the grille (See FIG. 1).

2. Remove the screw from the front of the microwave oven for wire protector and remove the wire protector(see Fig. 1).

3. Remove the screw from the top center tab of the control panel (See FIG. 2).

4. From the top and back of the control panel, pull out the Fuse Holder.

5. Without touching the metal ends, remove the defective line fuse from its holder and install a new one in its place.

6. Mount the control panel to the oven and secure it with its mounting screw.

7. Mount the vent grille to the microwave oven and check out the operation.

W ARNING :

Personal Injury Hazard Disconnect from the electrical supply before srvicing the unit. Failure to do so could result shock or other personal injury.

FIG. 5

6. REPLACING THE VENT MOTOR CAPACITOR

1. Remove the vent grille from the microwave oven (See Cabinet Removal).

2. Remove the screw from the top center tab of the control panel.(See FIG. 2)

3. Remove the screw from the top center tab of wire protector.

4. Disconnect the two wire connectors from the vent motor capacitor terminals.

5. Remove the screw for vent motor capacitor and remove it, then install a new capacitor in its place.

6. Reconnect the wires to the new vent motor capacitor terminals, as shown in the FIG. 6.

7. Reinstall the control panel and the vent grille on the microwave oven.

W ARNING :

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.

FIG. 6

7. REPLACING/ADJUSTING - INTERLOCK SWITCHES

-REPLACING A SWITCH

1. Disconnect the electrical supply to the microwave oven.

2. Remove the vent grille and the cabinet from the microwave oven (See cabinet removal on FIG. 1).

3. Remove the screw from the center of wire protector.

4. Remove the screw from the top center tab of the control panel (See FIG. 2).

5. From the top and back of the control panel, lift the top locking tab and Pull the top of the panel out slightly, then lift the bottom tabs of the panel out of the slots and pull it forward. Set the panel inside the oven cavity while you work. Refer to FIG. 7 for the following steps:

6. Remove the two mounting screws from the interlock switch assembly, and position the assembly so you can easily access the switches and wiring.

7. Refer to REMOVE SWITCH in FIG. 7-1 for the interlock switches the interlock switch housing assembly, and remove the switch from the housing as shown.

8. One at a time, pull the wire connectors off the defective switch, and reconnect them to the same terminals on the replacement switch (See FIG. 7-1).

9. Sanp the new switch into place on the switch housing.

10. Mount the interlock switch assembly to the chassis flange with two screws (See FIG. 7).

W ARNING :

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.

FIG. 7

-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.

2. Mount the control panel to the oven with the screw you removed earlier.

3. Mount the vent grille to the microwave oven and check out the operation of the switches.

W ARNING :

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.

NOTE :

Interlock switch replacement Whenever safty interlock switches are replaced: Refer to the following diagram. Check the connection of monitor switch after replacement. Perform the electrical continuity check of interlock switches and microwave emission test mentioned in this manual.

FIG. 7-1

8. REPLACING THE THERMOSTAT (BOTTOM/VENT)

1. Disconnect the electric supply to the microwave oven.

2. Remove the vent grille and the cabinet from the microwave oven (See cabinet removal on FIG. 1).

3. Remove the wire protector(see Fig. 4).

4. Remove the screw from the top center tab of the control panel. (See FIG. 2).

5. From the top and back of the control panel, lift the top locking tab and pull the top of the panel out slightly, then lift bottom tabs of the panel out of the slots and pull it forward. Set the panel inside the oven cavity while you work.

Refer to FIG. 8 and the inset for the following steps:

6. Remove the mounting screw from the bottom thermostat and lift the bottom flange out at slot in the chassis (See FIG. 8)

7. Unplug the two wire connectors from the bottom thermostat.

8. Connect the two wires to the new bottom thermostat.

9. Insert the bottom tab of the bottom thermostat into the chassis slot, and secure the thermostat with its mounting screw.

10. Mount the Control panel to the oven and screw it with its mounting screw.

11. Mount the vent grille to the microwave oven and check out the operation.

* Vent thermostat is same as bottom thermostat method. (See FIG. 8-2)

W ARNING :

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.

FIG. 8

9. REPLACING THE TRAY MOTOR

1. Remove 4 screws from the base plate and remove it. Refer to the FIG. 9 for the following steps:

2. Pull the connectors off the tray motor terminal.

3. Remove the screws from the tray motor and remove the motor.

4. Install the coupler onto the new tray motor shaft.

5. Mount the new motor to the oven with its the screws.

6. Connect the wires to the tray motor terminal.

7. Reinstall the base plate in the oven.

8. Secure its 4 screws.

W ARNING :

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.

FIG. 9

10. REPLACING A COOKTOP LIGHT SOCKET

1. Pull the connectors off the cook-top light socket terminals set the base plate aside.

2. Remove the screw for the cook-top light socket and remove it.

3. Mount the new light socket into the holder.

4. Reattatch the connectors with the orange and brown wires over the light socket terminals.

5. Mount the base plate to the microwave oven.

W ARNING :

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.

FIG. 10

11. REPLACING THE DOOR ASSEMBLY

Refer to FIG. 11 for the following steps:

1. Remove the Grille.

2. Open the door and lift the door.

W ARNING :

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.

FIG. 11

12. REPLACING THE GASKET

Refer to FIG. 12 for the following steps:

1. Open the oven door.

2. Pry out the gasket along the edges of the door with a putty knife.

3. Install the new gasket so that it fits tightly into place inside the door.

W ARNING :

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.

FIG. 12

13. REPLACING

-THE CAVITY THERMOSTAT

1. Remove the microwave oven from the microwave oven location.

2. Remove the vent grille and cabinet from the microwave oven. (See the cabinet removal)

3. Remove the 2 screws for supporter from the microwave oven.

4. Remove the power cord (see the replacing the powercord, Fig. 16)

5. Remove 4 screws for the vent motor and air guide top.

6. Remove the vent motor and lift the air guide top. (See FIG. 13-1)

7. Unplug and replace the two wire connectors from the cavity thermostat. (See FIG. 13-2)

8. Install the new cavity thermostat and reinstall the air guide top, vent motor, cabinet and vent grille on the microwave oven.

W ARNING :

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.

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 personal injury.

FIG. 13

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