Daewoo KOC-621Q User manual

Brand: Daewoo

Model: KOC-621Q

Category: Microwaves

Type: User manual

This manual is also suitable for

Service Manual

Microwave Oven

Model: KOC-621Q0S

S/M NO. : C621Q0S001

DAEWOO ELECTRONICS CO., LTD.

http://svc.dwe.co.kr Dec. 2001

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

microwave 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.

(c)Before turning on power to the microwave oven for any service test or inspection within the microwave

generating 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.

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

1. SAFETY AND PRECAUTIONS....................................................................................................................................2

2. SPECIFICATIONS ........................................................................................................................................................3

3. EXTERNAL VIEW.........................................................................................................................................................3

3-1. OUTER DIMENSION..........................................................................................................................................3

3-2. FEATURE DIAGRAM .........................................................................................................................................4

4. INSTALLATION............................................................................................................................................................5

5. CONTROL PANEL .......................................................................................................................................................6

6. DISASSEMBLY AND ASSEMBLY..............................................................................................................................7

7. INTERLOCK MECHANISM AND ADJUSTMENT.....................................................................................................15

8. TROUBLE SHOOTING GUIDE..................................................................................................................................16

9. MEASUREMENT AND TEST.....................................................................................................................................22

9-1. MEASUREMENT OF THE MICROWAVE POWER OUTPUT........................................................................22

9-2. MICROWAVE RADIATION TEST....................................................................................................................23

9-3. COMPONENT TEST PROCEDURE................................................................................................................24

9-4. COMPONENT ACTION....................................................................................................................................25

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

11. EXPLODED VIEW AND PARTS LIST ..................................................................................................................27

11-1. DOOR ASSEMBLY.........................................................................................................................................27

12-2. CONTROL PANEL ASSEMBLY.....................................................................................................................27

13-3. TOTAL ASSEMBLY........................................................................................................................................27

12. PRINTED CIRCUIT BOARD ....................................................................................................................................29

13. P.C.B CIRCUIT DIAGRAM.......................................................................................................................................33

1. 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.

(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 servicing, a microwave emission check should be performed prior to servicing the

oven.

(1) inform the manufacturer, importer or assembler,

(2) repair the unit at no cost to the owner,

(3) attempt to ascertain the cause of the excessive leakage,

(4) 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 immediately.

IMPORTANT

The wire 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 to the terminal in the plug which is marked with the

letter ‘E’, earth symbol or coloured 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.

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

3. EXTERNAL VIEW

470

285

376

2. SPECIFICATIONS

MODEL KOC-621Q0S

POWER SUPPLY 230V~50HZ, SINGLE PHASE WITH EARTHING

MICROWAVE 1250W

POWER GRILL 1250W

CONSUMPTION OVEN 1650W

COMBINATION 2500W

MICROWAVE ENERGY OUTPUT 800W(IEC705)

MICROWAVE FREQUENCY 2450MHz

OUTSIDE DIMENSIONS (W X H X D) 470X285X376mm (18.5X11.2X14.8 in.)

CAVITY DIMENSIONS (W X H X D) 295X167X300mm (11.6X6.6X11.8 in.)

NET WEIGHT APPROX. 15kg (33.1 lbs.)

TIMER Oven: 99 minutes, M/W: 60 minutes, Grill: 30 minutes

FUNCTION SELECTIONS MICROWAVE/ GRILL/ OVEN/ COMBINATION

POWER SELECTIONS 10 LEVELS

CAVITY VOLUME 0.6 Cu. Ft

* Specifications are subject to change without notice.

3-1. OUTER DIMENSION

M/W

1. Roast Beef

3. Roast Chicken

5. Vegetable

Auto Cook

M/W Def. Grill Temp g

2. Roast Pork

4. Fish Fillets

Grill

Combi

Tem p

Clock

Combi

KOC-621Q

Stop/

Clear

Defrost

1000g

100g

10m.

1m.

10s.

Auto Cook

Start/

Speedy cook

1 2

e w q 7

3 4 5

11.DOOR HOOK

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

will immediately stop operating.

12.DOOR VIEWING SCREEN

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

13.TOP HEATER

Turns on when convection, grill and combi cooking is selected.

14.OVEN LAMP

Automatically turns on during oven operating.

15.SAFETY INTERLOCK SYSTEM

16.CONTROL PANEL

17. UNDER HEATER

18. METAL RACK

19.TURNTABLE TRAY

Rotates during cooking and ensure even distribution of Microwaves.

It can also be used as a cooking utensil.

10.TRAY GUIDE

This must always be used for cooking together with the turntable tray.

11. COUPLER

This fits over the shaft in the center of the ovens cavity floor. This is to remain in the oven for all cooking.

12. OVEN FRONT PLATE

13.DOOR SEAL

Door seal maintains the microwave energy within the oven cavity and prevents microwave leakage.

3-2. FEATURE DIAGRAM

1. Steady, flat location

This microwave oven should be set on a steady, flat surface.

This microwave oven is designed for counter top use only.

2. Leave space behind and side

All air vents should be kept a clearance. If all vents are covered during operation, the oven may overheat and, eventually,

cause failure.

3. Away from Radio and TV sets

Poor television reception and radio interference may result if the oven is located close to a TV, Radio, antenna or feeder

and so on.

Position the oven as far from them as possible.

4. Away from heating appliances and water taps

Keep the oven away from hot air, steam or splash when choosing a place to position it, or the insulation might be

adversely affected and breakdowns occur.

5. Power supply

• Check your local power source. This microwave oven requires a current of approximately 12 amperes, 230V, 50Hz.

• Power supply cord is about 1.2 meters long.

• The voltage used must be the same as specified on this oven. Using a higher voltage may result in a fire or other

accident causing oven damage. Using low voltage will cause slow cooking. We are not responsible for damage

resulting from use of this oven with a voltage of ampere fuse other than those specified.

• 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.

If any of the above are visible, DO NOT INSTALL, and notify dealer immediately.

7. Do not operate the oven if it is colder than room temperature.

(This may occur during delivery in cold weather.) Allow the oven to become room temperature before operating.

This appliance must be earthed. In the event of an electrical short circuit, earthing reduces the risk of the electric shock by

providing an escape wire for the electric current. This appliance is equipped with a cord having a earthing wire with a

earthing plug. The plug must be plugged into an outlet that is properly installed and earthed.

4. INSTALLATION

EARTHING INSTRUCTIONS

WARNING

Improper use of the earthing plug can result in a risk of electric shock.

Consult a qualified electrician of serviceman if the earthing instructions are not completely understood, or if doubt

exists as to whether the appliance is properly earthed, and either:

If it is necessary to use an extension cord, use only a 3-wire extension cord that has a 3-blade earthing plug, and a

3-slot receptacle that will accept the plug on the appliance.

The marked rating of the extension cord should be equal to or greater than the electrical rating of the appliance, or

Do not use an extension cord.

5. CONTROL PANEL

M/W

1. Roast Beef

3. Roast Chicken

5. Vegetable

Auto Cook

M/W Def. Grill Temp g

2. Roast Pork

4. Fish Fillets

Grill

Combi

Temp

Clock

Combi

KOC-621Q

Stop/

Clear

Defrost

1000g

100g

10m.

1m.

10s.

Auto Cook

Start/

Speedy cook

BUTTONS

1. m/w - Press to select microwave power level.

2. defrost - Press to select weight/time defrost mode.

3. grill - Press to select grill.

4. combi - Press to select combi cooking mode.

5. temp - Press to select temperature.

6. 10m. - Press to set time and weight.

7. 1m. - Press to set time and weight.

8. 10s. - Press to set time.

9. clock - Use to set clock.

10. auto cook - Press to select auto cook menu.

11. stop/clear - Press once to stop a programme, and

twice to cancel a programme.

12. start/speedy cook - Press to start a programme,

also for speedy start (each press adds 30 seconds

microwave cooking time).

6. 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 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 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.

The microwave oven is designed to be used while grounded.

It is imperative, therefore, to 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, 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 screwdriver to discharge.

4. When the 15A fuse is blown out due to the operation of the monitor

switch; replace primary interlock switch, secondary interlock switch

and interlock monitor switch.

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 replacing the magnetron.

WARNING : When servicing the appliance, take 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.

SHORT

NOTE: After replacting the door assembly, perform a

check of correct alignment with the hinge and

cavity front plate.

1. To remove cabinet

1) Remove four screws on cabinet back.

2) Push the cabinet backward.

2. 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 for assemby.

3. To remove door parts.

REF NO. PART CODE PART NAME DESCRIPTION Q’TY REMARK

A01 3512203410 FRAME DOOR ABS 1

A02 3517004800 BARRIER-SCREEN *O TEMP GLASS T3.2 1

A03 3515203000 STOPPER HINGE *T AS KOC-621S5J 1

A04 3511709400 DOOR PAINTING AS KOC-621S5J 1

A05 3517004700 BARRIER-SCREEN *I TEMP GLASS T3.0 1

A06 3512301100 GASKET DOOR PBT 1

A07 3513101000 HOOK POM 1

A08 3515101700 SPRING HOOK PW1 1

(1) Remove the gasket door(A06) from door plate.

(2) Remove the door frame (A01) from door plate(A04).

(3) Remove the stopper hinge top(A03) from door plate(A04).

(4) Remove the spring(A08) and the hook(A07).

(5) Remove the barrier screen outer(A02) from door frame(A01).

(6) Reverse the above steps for reassembly.

4. 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.

• Tighten two screws.

(2) To reduce gap located on part ‘B’.

• Loosen two screws on stopper hinge under, and then push the

door to contact the door seal to oven front surface.

• Tighten two screws.

M/W

1. Roast Beef

3. Roast Chicken

5. Vegetable

Auto Cook

M/W Def. Grill Temp g

2. Roast Pork

4. Fish Fillets

Grill

Combi

Tem p

Clock

Combi

KOC-621Q

Stop/

Clear

Defrost

1000g

100g

10m.

1m.

10s.

Auto Cook

Start/

Speedy cook

NOTE : A small gap may be acceptable if the microwave leakage does not exceed 4mW/cm

5. To remove control panel parts.

REF NO. PART CODE PART NAME DESCRIPTION Q’TY REMARK

B01 3518523500 SWITCH MEMBRANE KOC-621Q0S 1

B02 3516715810 CONTROL-PANEL ABS 1

B03 3514325720 PCB AS KOC-621Q0S 1

B04 7112401211 SCREW TAPPING T1 TRS 4X12 MFZN 4

(1) Remove four screws(B04) which secure the PCB AS(B03).

(2) Pull out the PCB AS(B03) from control panel(B02).

(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

6. To remove high voltage capacitor.

1) Remove a screw which secure the grounding ring

terminal of the H.V. diode and the capacitor holder.

2) Remove the H.V. diode from the capacitor holder.

3) Reverse the above steps for reassembly.

◆ High voltage circuit wiring

7. To remove magnetron.

1) Remove a screw which secure the magnetron.

2) Remove the magnetron.

3) Reverse the above steps for reassembly.

8. To remove wind guide assembly.

1) Remove a screw for earthing.

2) Remove the noise filter from the wind guide.

3) Remove two screws which secure the wind guide assembly.

4) Draw forward the wind guide assembly.

5) Pull the fan from the motor shaft.

6) Remove two screws which secure the motor shaded pole.

7) Remove the motor shaded pole.

8) Reverse the above steps for reasembly.

9. To remove H.V.transformer.

1) Remove four screws holding the H.V.transformer.

2) Remove the H.V.transformer.

3) Reverse the above steps for reassembly.

10. To remove Top heater assembly parts.

1) Remove two screws

then pull out cover insulator *t as

and guide air outlet

2) Remove a hex nut

and hex nut

3) Pull out heater.

4) Reverse the above steps for reassembly.

REF NO. PART CODE PART NAME DESCRIPTION Q’TY REMARK

1 7112401011 SCREW TAPPING T1 TRS 4*10 MFZN 2

2 3511409700 COVER INSU *T AS KOC-621Q0S 1

3 3512513110 GUIDE AIR OUTLET SA1D-80 T0.5 1

4 7392500011 NUT HEX 6N-2-5 MFZN 1

5 7392500011 NUT HEX 6N-2-5 MFZN 1

6 3512803300 HEATER 230V 1150W 1B08965 1

11. To remove Motor synchro. And Under heater assembly parts.

1) Cut the cover parts from the base plate.

2) Remove a screw and then pull out Motor syncro.

3) Remove a screw

and then pull out the Under heater *U. assembly.

4) Remove a screw

5) Pull out the Heater *U

from the Cover heater *U

6) Reverse the above steps for reassembly.

REF NO. PART CODE PART NAME DESCRIPTION Q’TY REMARK

1 7122400811 SCREW TAPPING T2S TRS 4*8 MFZN 1

2 7113400814 SCREW TAPPING T1 BIN 4*8 MFNI 1

3 3512802000 HEATER *U 230V 400W R1837400 1

4 3515304000 SUPPORTER HEATER STS430 T0.5 1

5 3511404410 COVER HEATER *U STS430-2B/HL T0.6 1

CUTTING (8EA)

7. 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) 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 button of the microswitch. Then the button of the primary interlock switch

bring it under ON condition.

(2) Secondary interlock switch and interlock monitor switch

When the door is closed, the hook pushes the lock lever downward. The lock lever presses the button of the interlock

monitor switch to bring it under OFF condition and presses the button of the secondary interlock switch to bring it under

ON condition.

(3) Adjustment steps

a) Loosen the two mounting screws.

b) Adjust interlock switch assembly position.

c) Make sure that lock lever moves smoothly after adjustment is completed.

d) Tighten completely two mounting screws.

ADJUSTMENT :

Interlock monitor switch

When the door is closed, the interlock monitor switch should be opened before other switches are closed.

When the door is opened, the interlock monitor switch should be closed after other switches are opened.

NOTE :

Microwave emission test should be performed after adjusting interlock mechanism.

If the microwave emission exceed 4mW/cm

, readjust interlock mechanism.

8. TROUBLE SHOOTING GUIDE

Following the procedure below to check if the oven is defective or not.

1) Check grounding 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 tranformer, disconnect one load wire from these

parts and check continuity with the AC plug removed. To do otherwise may result in a false reading or damage to

your meter.

(TROUBLE 1) Oven does not operate at all : any inputs can not be accepted.

NOTE :

When electric parts are checked, be sure the power cord is not inserted the wall outlet.

Check wire harness, wiring and connection of the terminals and power cord before check the parts listed below.

CONDITION CHECK

Check continuity of

interlock monitor switch with

door closed

( COM↔NC )

Check continuity of

both primary and secondary

interlock switch with door closed

Malfunction of

Interlock

monitor switch

Malfunction of

interlock switch

RESULT

Continuity

No continuity

CAUSE REMEDY

Replace

(COM↔NC)

Fuse blows.

Replace

Shorted contacts

of primary

interlock Switch

Continuity Replace

Check continuity of

primary interlock switch contact with

door partially open until interlock

monitor switch contact close

( COM↔NC close )

Defective low

voltage

transformer

Defective

high voltage

transformer

0 Ωor infinite Replace

Replace

Check continuity of

primary winding of low voltage

transformer

Disconnect high voltage

fuse and operate the unit

Continuity

Approx.

790Ω

( normal )

Fuse again

blows

CONDITION CHECK

Check continuity of

magnetron Defective

magnetron.

RESULT

continuity

CAUSE REMEDY

Replace

Outlet has

proper

voltage

fuse does not

blow? Check continuity of noise filter

board Defective line

filter board

continuity Replace

Check continuity of

power supply cord

Defective touch

control circuit Replace

Open power

supply cord

continuity

Replace

NOTE : All these switches must be replaced at the same time, please refer to (7.Interlock mechanism and

adjustment) for adjustment instructions

(TROUBLE 2)

Display shows all figures selected, but oven does not start cooking, even though desired program and time

are set and start button is tapped.

CONDITION CHECK

Check continuity of

primary interlock switch Malfunction of

primary interlock

switch

RESULT

continuity

CAUSE REMEDY

Adjust or

replace

Turn table

motor and

oven lamp

not turn on

Check D.C voltage

being supplied to

RELAY(RY5) coil

Fault contacts

of RELAY

(RY5) or open

relay coil.

Replace

Check continuity of

secondary interlock

and D.O.M switch

Malfunction of

secondary

Interlock and

D.O.M switch

continuity Adjust or

replace

Defective touch

control Circuit

Approx.

13V DC

Replace

TROUBLE 3) No microwave oscillation even though fan motor rotates.

CONDITION CHECK RESULT

Check continuity of

high voltage capacitor terminals

with wires removed

Continuity

CAUSE

Defective

high voltage

transformer

Defective

high voltage

fuse

REMEDY

Replace

microwave

oscillation

Check continuity of

high voltage rectifier in forward

and backward

direction with DC megger

Continuity

in backward

direction

Defective high

voltage rectifier Replace

Connect megger leads to

magnetron terminal and

magnetron body

Continuity Defective

magnetron 2

1Check resistance of primary

and secondary coil of high

voltage transformer

0 Ωor ∞Defective

high voltage

transformer

Replace

Check continuity of

high voltage fuse

No microwave oscillation

continuity

2Check continuity of

magnetron heater with wires

removed

No continuity Defective

magnetron Replace

1Check continuity of filament

terminal of high voltage

transformer

No continuity Defective high

voltage

transformer

Replace

Check D.C voltage

being supplied to

RELAY (RY1) coil

0 V Defective

touch control

circuit

Replace

Approx.

13V DC Faulty contacts of

RELAY

(RY1) or open

relay coil

Replace

(TROUBLE 4)

Grill heater (upper heater) is not heated; food will not become hot.

CONDITION CHECK

Check continuity of

primary interlock switch Malfunction of

primary Interlock

switch

RESULT

continuity

CAUSE REMEDY

Adjust or

replace

Grill heater is

not heated.

Check D.C voltage

being supplied to

RELAY (RY3) coil

Faulty contacts of

RELAY

(RY3) or open

relay coil

Replace

Check continuity of

secondary interlock switch Malfunction of

secondary

interlock switch

continuity Adjust or

replace

Defective touch

control circuit

Approx.

13V DC

Replace

Check continuity of

heater Defective heater

continuity Replace

(TROUBLE 5)

Fan motor does no rotate.

CONDITION CHECK

Check continuity of

primary interlock switch Malfunction of

primary Interlock

switch

RESULT

continuity Adjust or

replace

Fan does

not rotate.

Check D.C voltage

being supplied to

RELAY (RY6) coil

Faulty contacts of

RELAY

(RY6) or

open relay coil

Replace

Check continuity of

secondary interlock

switch

Malfunction of

secondary

interlock switch

continuity Adjust or

replace

Defective touch

control circuit

Approx.

13V DC

Replace

Check continuity of

fan Defective fan

continuity Replace

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Daewoo KOC-621Q User manual

Brand: Daewoo

Model: KOC-621Q

Category: Microwaves

Type: User manual

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