Daewoo KOG-875T2S Service Manual

Service Manual

Microwave Oven

Model: KOG-875T2S

DAEWOO ELECTRONICS CO., LTD.

S/M No. : G875T2S001

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 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.

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.

TABLE OF CONTENTS

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

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

EXTERNAL VIEWS.....................................................................................................................................................................3

NAMES AND FUNCTION OF PARTS........................................................................................................................................4

CONTROL PANEL......................................................................................................................................................................5

INTERLOCK MECHANISM FUNCTIONS AND ADJUSTMENTS.............................................................................................6

PRECAUTIONS FOR DISASSEMBLY AND REPAIR...............................................................................................................8

DISASSEMBLY AND ASSEMBLY..............................................................................................................................................9

TROUBLE SHOOTING GUIDE ................................................................................................................................................17

MEASUREMENT ......................................................................................................................................................................23

COMPONENT TEST PROCEDURE........................................................................................................................................25

WIRING DIAGRAM...................................................................................................................................................................26

SCHEMATIC DIAGRAM...........................................................................................................................................................27

EXPLODED VIEWS AND PARTS LIST ...................................................................................................................................29

PRINTED WIRING BOARD......................................................................................................................................................32

P.C.B. CIRCUIT DIAGRAM ......................................................................................................................................................37

P.C.B. ASS’Y PART LIST .........................................................................................................................................................38

PROPER USE AND SERVICE PRECA UTIONS

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) This microwave oven weight 17.6kg (38.9 lbs.) and must be placed on a horizontal base strong enough to support this weight.

2) The oven should be placed as far from high temperature source and vapour as possible.

3) The power supply cord is about 1.1m (3.2ft) long. Earthing is required when connecting the power source.

4) Maximum power consumption of this oven is approximately 2.5Kw(230V). It is suggested that the unit is operated on such power line (about 13 amperes) that can provide more power than this rating.

5) Object must not be placed on the top enclosure so as not to obstruct air flow for ventilation.

The wires in this mains lead coloured in accordance with the following code.

Green-and-yellow : Earth Blue : Neutral

Brown : Live As the colours of the wires in the mains lead of this appliance may not correspond with the coloured markings identifying the terminals in your plug, proceed as follows: The wire which is coloured green-and-yellow must be connected the the terminal in the plug which is marked with the letter ‘E’ or by earth symbol or green-and-yellow. The wire which is coloured blue must be connected to the terminal which is marked with the letter ‘N’ or coloured black. The wire which is coloured brown must be connected to the terminal which is marked with the letter ‘L’ or coloured red.

WARNING : This appliance must be earthed.

NOTE : This oven is designed for counter-top use only.

IMPORTANT

POWER SUPPLY 230V ~ , 50Hz single phase with earthing

POWER CONSUMPTION 1,400 W

MICROWAVE OUTPUT POWER 900 W (IEC 705)

FREQUENCY 2,450 MHZ GRILL POWER CONSUMPTION 1,400 W COMBINATION HEATING POWER CONSUMPTION 1,400 W OUTSIDE DIMENSIONS (W X D X H ) 501 X 320 X 413 mm (19.7 X 12.6 X 16.2 in.) CAVITY DIMENSIONS (W X D X H) 310 X 229 X 320 mm (12.2 X 9.0 X 12.6 in.) NET WEIGHT 17.6 kg (38.9 Ibs.) TIMER 60 minutes SELECT FUNCTION Microwave/Grill /Combination Heating MICROWAVE POWER LEVEL 10 stages

* Specifications subject to change without notice.

501

320

413

M/W

PROGRAM

COOK

GRILL COMBI WEIGHT-TIME

DEFROST

M/W

WEIGHT DEFROST

TIME

DEFROST

GRILL COMBI

1MIN

PROGRAM COOK

1. Roast Beef

2. Roast Port

3. Roast Chicken

4. Fish Fillets

5. Vegetable SPEEDY

COOK

STOP/CLEAR START/CLOCK

Fig. 1 Front View Fig. 2 Side View

SPECIFICATIONS

EXTERNAL VIEWS

NAMES AND FUNCTION OF PAR TS

1 2 6 3 4 5

M/W

PROGRAM

COOK

GRILL COMBI WEIGHT-TIME

DEFROST

M/W

WEIGHT

DEFROST

TIME

DEFROST

GRILL COMBI

1MIN

PROGRAM COOK

1. Roast Beef

2. Roast Port

3. Roast Chicken

4. Fish Fillets

5. Vegetable SPEEDY

COOK

STOP/CLEAR START/CLOCK

Door latch

When the door is closed it will automatically lock shut. If the door is opened while the oven is operating. The magnetron will automatically shut off.

Door seal

The door seal maintains the microwave within the oven cavity and prevents microwave leakage.

Oven cavity

Spatter shield

Protects the microwave outlet from splashes of cooking foods.

Safety interlock system

Prevents the oven from operating while the door is opened.

Heater

Grill or Combi-Mode has need for the heater.

lass cooking tray

Made of special heat resistant glass. The tray must always be in proper position before operating. Do not cook food directly on the tray.

Roller guide

Supports the glass cooking tray.

Door screen

Allows viewing of food. The screen is designed so that light can pass through, but not the microwaves.

CONTROL PANEL

M/W

PROGRAM

COOK

GRILL COMBI WEIGHT-TIME

DEFROST

M/W

WEIGHT

DEFROST

TIME

DEFROST

GRILL COMBI

1MIN

PROGRAM COOK

1. Roast Beef

2. Roast Pork

3. Roast Chicken

4. Fish Fillets

5. Vegetable SPEEDY

COOK

STOP/CLEAR START/CLOCK

When blinking, the oven is operating in COMBI cooking.

When blinking, the oven is operating in GRILL cooking.

When blinking, the oven is operating in MICROWAVE cooking.

When blinking, the oven is operating in PROGRAM cook.

Microwave Power Level -

Used to select the variable microwave power level. If this button is pressed for more than 1.3 seconds, number is scrolled up automatically.

DIAL KNOB - Used to enter the cooking time and weight input.

Stop/Clear Button - Used to pause or clear all information manually put into the oven.

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.

When you touch this button, Cooking time is increased by the step of 1 minute.

Function Button - Used to select desired oven operation.

MICROWAVE GRILL WEIGHT DEFROST COMBINATION TIME DEFROST +1 MIN PROGRAM COOK

Speedy Cook Button Used to quickly program cooking time in 30 seconds increments.

Start/Clock Button Used to start operation and to set the clock.

M/W

GRILL

COMBI

1 MIN

PROGRAM

COOK

WEIGHT

DEFROST

TIME

DEFROST

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. If the door is not closed properly, the oven will not operate. When the door is closed, the hook pushes the lever downward. The lever press the button of the primary interlock switch to bring it under ‘ON’ condition.

INTERLOCK MECHANISM FUNCTIONS AND ADJUSTMENTS

Mounting screw

Hook

Primary interlock switch

(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’ condition.

- Adjustment

Interlock monitor switch

When the door is closed, the monitor switch should be opened before other switches close. When the door is opened, the monitor switch should be closed after other switches open.

Adjustment steps :

a) Loosen the two mounting screws. b) Adjust the interlock switch assembly position. c) Make sure that the latch lever moves smoothly after adjustment is completed. d) Completely tighten the two mounting screws.

PRECA UTIONS 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. 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 war rubber gloves when servicing the high voltage side.

(3)Warning about the electric charge in the high voltage capacitor. When inspecting and repairing the high voltage side,

always short the capacitor terminals and make sure of discharge.

1. Check the earthing.

Do not operate on a 2-wire extension cord. The microwave oven is designed to be used when earthed. It is imperative, therefore, to makes sure it is earthed properly before beginning repair work.

2. Warning about the electric charge in the high voltage capacitor.

For about 30 seconds after the operation stops, 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 screw driver to discharge.

(4) When the 15 Amp fuse (normal blow type) is blown out due to the operation of the monitor switch; replace primary,

secondary interlock switch and monitor switch. Refer to 7 page for the necessary adjustment.

(5)After repair or replacement of parts, make sure that the screws are properly tightened and all electrical connections are

tightened.

(6)Do not operate without cabinet.

CAUTION : Service personnel should remove their watches whenever working close to or repairing the magnetron.

WARNING : When servicing the appliance, need a care of touching or replacing high potential parts because of

electrical shock or exposing microwave. These parts are as follows - H.V. Transformer, magnetron, H.V. Diode, H.V. Capacitor.

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 2.

2) Remove back-cover 3.

3) Pull the fan 5 to the motor shaft.

4) Release two screws 1 which secure the motor shaded pole 4.

5) Reverse the above steps for reassembly.

DISASSEMBLY AND ASSEMBLY

Fig. 2

Fig. 1

54 3

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

H.V. Trans

H.V. Copacitor

Mognetron

H.V.Diode

H.V.Fuse

Fig. 3

4. To remove magnetron. (Refer to Fig. 4)

1) Remove a screw 2 which secure the magnetron 1.

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 leakage. Whenever repair work is carried out on magnetron, check the microwave leakage. It shall not exceed 4mW/cm

for a fully assembled oven with door normally closed.

Magnetron antenna

Metallic gasket plate

Cooling fin

Filament terminal

Wave guide

Magnetron antenna

Metallic gasket plate

Fig. 4

+ 28 hidden pages

Daewoo KOG-875T2S Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual