Daewoo KOC-621Q0S Schematic

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Service Manual

Microwave Oven

Model: KOC-621Q0S

S/M NO. : C621Q0S001

DAEWOO ELECTRONICS CO., LTD.

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

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

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 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. 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

Temp

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 INSTR UCTIONS

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. V egetab le

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

Temp

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/cm2.

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.

6. T o remo ve high v oltage 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. T o remo ve magnetr on.

1) Remove a screw which secure the magnetron.

2) Remove the magnetron.

3) Reverse the above steps for reassembly.

Metallic gasket

Magnetron antenna

plate

Cooling fin

Filament terminal

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 1then pull out cover insulator *t as 2and guide air outlet 3.

2) Remove a hex nut

and hex nut 5.

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 assembl y 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 5.

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 SHOO TING 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 Ω or 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

1 Check resistance of primary

and secondary coil of high voltage transformer

0 Ω or ∞

Defective

high voltage

transformer

Replace

Check continuity of

high voltage fuse

No microwave oscillation

continuity

2 Check continuity of

magnetron heater with wires removed

No continuity

Defective

magnetron

Replace

1 Check 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

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

(TROUBLE 6) Lower 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

Lower heater Is not heated

Check D.C voltage

Being supplied to

RELAY (RY4) coil

Faulty contacts of

RELAY

(RY4) 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

CONDITION CHECK

Check each pad for continuity

of the pad

Malfunction of

Membrane.

RESULT

Normal

CAUSE REMEDY

Replace

C/PANEL

assembly.

Display does

not show

programming

at all, even if

keyboard is

touched.

(TROUBLE 7) The following visual conditions indicate a probable defective touch control Circuit or Membrane.

1. Incomplete segments.

1) segment missing

2) partial segments missing

3) digit flickering other than normal fluorescent slight flickering

2. A distinct change in the brightness of one or more numbers exists in the display

3. One or more digits in the display are not on when they should be.

4. Display does not count down or up with time cooking or clock operation.

5. Oven is programmable and cooks normally but no display shows.

6. Display obviously jumps in time while counting down.

7. Display counts down noticeably too fast while cooking.

M/W Def. Grill Temp g

CAUSE

REMEDY

(TROUBLE 8) When “Err 2” or “Err 3” come on display.

CONDITION CHECK

Check continuity of thermistor

(resistance of thermistor)

Defective

thermistor

RESULT

0Ω or infinite

Replace

“Err 2” or

“Err 3” come

on display

Check continuity of heater

(upper, lower)

Defective touch

control circuit

Replace

Approx

200k~300kΩ

(room

temperature)

Defective

heater

continuty

continuity

Replace

9. MEASUREMENT AND TEST

9-1. MEASUREMENT OF THE MICROW AVE POWER OUTPUT

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.

PROCEDURE

1. Microwave power output measurement is made with the microwave oven supplied at rated voltage and operated at its maximum microwave power setting with a load of 1000 ± 5cc of potable water.

2. The water is contained in a cylindrical borosilicate glass vessel having a maximum material thickness of 3 mm and an outside diameter of approximately 190 mm.

3. The oven and the empty vessel are at ambient temperature prior to the start of the test. The initial temperature of the water is 10 ± 2°C (50 ± 3.6°F). If is measured immediately before the water is added to the vessel. After addition of the water to the vessel, the load is immediately placed on the center of the shelf, which is in the lowest normal position.

4. Microwave power is switched on.

5. Heating time should be exactly A seconds. (Refer to table as following) Heating time is measured while the microwave generator is operating at full power. The filament heatup time for magnetron is not included.

6. The initial and final temperature of water is selected so that the maximum difference between the ambient and final water temperature is 5K.

7. The microwave power output P in watts is calculated from the following formula:

• ∆ T is difference between initial and ending temperature.

• t is the heating time.

The power measured be B (Refer to SPECIFICATIONS) W ± 10.0 %.

✻ Power level table

CAUTION

1. Water load should be measured exactly to 1 liter.

2. Input power voltage should be exactly specified voltage (Refer to SPECIFICATIONS).

3. Ambient temperature should be 20 ± 2°C (68 ± 3.6°F)

P = 4187 X ∆ T/t

Power level

High

Sauté

Reheat

Medium high

Simmer

percentage

100% (P-Hi)

90% (P-90) 80% (P-80) 70% (P-70) 60% (P-60)

Output

800W 720W 630W 550W 470W

Power level

Medium

Medium low

Low

Defrost

Warm

percentage

50% (P-50) 40% (P-40) 30% (P-30) 20% (P-10) 10% (P-10)

Output

390W 300W 220W 140W

90W

9-2. MICROW AVE RADIATION TEST

PROCEDURE

1. Prepare Microwave Energy Survey Meter, 600cc glass beaker, and glass thermometer 100°C (212°F).

2. Pour 275cc ± 15cc of tap water initially at 20 ± 5°C (68 ± 9°F) in the 600 cc glass beaker with an inside diameter of approx. 95 mm(3.5 in.).

3. Place it at the center of the tray and set it in a cavity.

4. Close the door and operate the oven.

5. Measure the leakage by using Microwave Energy Survey Meter with dual ranges, set to 2450MHz.

1) Measured radiation leakage must not exceed the value

prescribed below. Leakage for a fully assembled oven with door normally closed must be less than 4mW/Cm

2) When measuring the leakage, always use the 5 cm (2 in.)

space cone with probe. Hold the probe perpendicular to the cabinet and door. Place the space cone of the probe on the door, cabinet, door seem, door viewing screen, the exhaust air vents and the suction air vents.

3) Measuring should be in a counter-clockwise direction at a rate of 1 in./sec. If the leakage of the cabinet door

seem is unknown, move the probe more slowly.

4) When measuring near a corner of the door, keep the probe perpendicular to the areas making sure the probe

end at the base of the cone does not get closer than 2 in. from any metal. If it does not, erroneous reading may result.

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

WARNING

1. Make sure to check the microwave leakage before and after repair of adjustment.

2. Always start measuring of an unknown field to assure safety for operating personnel from microwave energy.

3. Do not place your hands into any suspected microwave radiation field unless the safe density level is known.

4. Care should be taken not to place the eyes in direct line with the source of microwave energy.

5. Slowly approach the unit under test until the radiometer reads an appreciable microwave leakage from the

unit under the test.

9-3. COMPONENT TEST PROCEDURE

• High voltage is present at the high voltage terminal of the high voltage transformer during any cooking cycle.

• It is neither necessary nor advisable to attempt measurement of the high voltage.

• Before touching any oven components or wiring, always unplug the oven from its power source and discharge the

capacitor.

1. High voltage transformer

1) Remove connections from the transformer terminals and check continuity.

2) Normal readings should be as follows : Secondary winding ... Approx. 100 Ω±10% Filament winding ... Approx. 0 Ω Primary winding ... Approx. 1.2 Ω

2. High voltage capacitor

1) Check continuity of capacitor with meter on the highest OHM scale.

2) A normal capacitor will show continuity for a short time, and then indicate 10MΩ once the capacitor charged.

3) A shorted capacitor will show continuous continuity.

4) An open capacitor will show constant 10MΩ.

5) Resistance between each terminal and chassis should be infinite.

3. High voltage diode

1) Isolate the diode from the circuit by disconnecting the leads.

2) With the ohmmeter set on the highest resistance scale measure the resistance across the diode terminals. Reverse the meter leads and again observe the resistance reading. Meter with 6V, 9V or higher voltage batteries should be used to check the front-back resistance of the diode, otherwise an infinite resistance may be read in both directions. A normal diode's resistance will be infinite in one direction and several hundred k Ω in the other direction.

4. Magnetron

For complete magnetron diagnosis, refer to "Measurement of the Microwave Power Output." Continuity checks can only indicate and open filament or a shorted magnetron. To diagnose for an open filament or a shorted magnetron,

1) Isolate magnetron from the circuit by disconnecting the leads.

2) A continuity check across magnetron filament terminals should indicate 0.1 Ω or less.

3) A continuity check between each filament terminal and magnetron case should read open.

5. Fuse

If the fuse in the primary and monitor switch circuit is blown when the door is opened, check the primary and monitor switch before replacing the blown fuse. In case the fuse is blown by an improper switch operation, replace the defective switch and fuse at the same time. Replace just the fuse if the switches operate normally.

4. COMPONENT ACTION

COOKING MODE

MANUAL M/W MODE GRILL

COMBI TEMP DEFROST

AUTO ROAST BEEF COOK ROAST PORK

ROAST CHICKEN FISH FILLETS VEGETABLE

MAGNETRON

●

UPPER ELEMENT

●

LOWER ELEMENT

●

10. WIRING DIA GRAM

11. EXPLODED VIEW AND PARTS LIST

1. DOOR ASSEMBLY

Refer to 6. Disassembly and assembly.

2. CONTROL PANEL ASSEMBLY

Refer to 6. Disassembly and assembly.

3. TOTAL ASSEMBLY

NO PART NAME DESCRIPTION PART CORD Q'TY

A00 DOOR AS KOG-62150S 3511709210 1 B00 CONTROL-PANEL AS KOC-621Q0S 3516726550 1 F01 CABINET AS KOC-621Q0S 3510806710 1 F02 SCREW TAPPING T1 TRS 4*10 MFZN 7112401011 3 F03 SENSOR TEMPERATURE PTM-K312-D7 3514801400 1 F04 SCREW TAPPING T1 TRS 4*10 MFZN 7112401011 1 F05 SCREW TAPPING T2S TRS 4*12 MFZN 7122401211 1 F06 SCREW TAPPING T1 TRS 4*10 MFZN 7112401011 4 F07 SCREW TAPPING T2S TRS 4*12 MFZN 7122401211 2 F08 SCREW TAPPING T1 TRS 4*10 MFZN 7112401011 1 F09 CORD POWER AS 3X1.5 80X80 120-RTML 1.4M 35113A5QJ5 1 F10 NOISE-FILTER DWLF-M02 3518603710 1 F11 SCREW TAPPING T1 TRS 4*10 MFZN 7112401011 1 F12 SCREW TAPPING T2S PAN 4X30 MFZN 7121403011 2 F13 MOTOR SHADED POLE 230V 25W MW15CA-K01 3963512910 1 F14 GUIDE WIND PP 5113MF6 A353B 3512513700 1 F15 FAN P.P GF20 3511800100 1 F16 NUT HEX 6N-2-5 MFZN 7392500011 1 F17 SCREW TAPPING T2S TRS 4*12 MFZN 7122401211 2 F18 MAGNETRON 2M218H(F) 3518002200 1 F19 SPECIAL SCREW T2 FLANGE 4X13 PW SE M 3516002700 1 F20 SCREW TAPPING T1 BIN 4*8 MFNI 7113400814 1 F21 HEATER *U 230V 400W R18374001 3512802000 1 F22 SUPPORTER HEATER *U STS430 T0.5 3515304000 1 F23 SCREW TAPPING T2S TRS 4*8 MFZN 7122400811 1 F24 COVER HEATER *U STS430-2B/HL T0.6 3511404410 1 F25 SCREW TAPTITE TT3 TRS 4X8 MFZN 7272400811 1 F26 HOLDER HV CAPACITOR SECC T0.6 3513003200 1 F27 CAPACITOR HV 2100VAC 0.98UF #187 3518302200 1 F28 DIODE HV "HVR-1X-3AB 12KV #187" 3518400400 1 F29 FUSE HV 5KV 0.7A HV-41A70-1 #187 3518700230 1 F30 TRANS HV DW-R80S0-62T 3518118710 1 F31 SPECIAL SCREW TT3 HEX 4X8 FLG MFZN 3516003700 4 F32 BASE SBHG T0.8 3510310800 1 F33 FOOT DASF-310 3512101400 4 F34 SCREW TAPPING T1 TRS 4*10 MFZN 7112401011 5 F35 SCREW TAPTITE TT3 TRS 4X8 MFZN 7272400811 2 F36 STOPPER HINGE *U AS KOR-121M0A 3515202800 1 F37 HARNESS MAIN KOC-621Q0S 3512718900 1 F38 SW MICRO VP-533A-OF SPNO #187 200G 4415A17352 1 F39 SW MICRO VP-531A-OF/SZM-V16-FA-61 4415A66910 1 F40 SW MICRO VP-533A-OF SPNO #187 200G 4415A17352 2 F41 LEVER LOCK POM 3513701300 1 F42 LOCK POM 3513807900 1 F43 LAMP BL 240V 25W T25 C7A H187 3513601600 1 F44 MOTOR SYNCRO 100/240V 4W GM-16-24FD16 3966030500 1 F45 SCREW TAPPING T2S PAN 4X10 MFZN 7121401011 1 F46 SCREW TAPTITE TT3 TRS 4X8 MFZN 7272400811 2 F47 COVER WAVE GUIDE MICA T0.35 3511404710 1 F48 COUPLER PTFE 3517401900 1 F49 GUIDE TRAY SPP T1.0 3512512810 1 F50 TRAY METAL SPP T0.6 3517205500 1 F51 TRAY RACK AS KOC-621Q0S 3517208400 1 F52 SCREW TAPPING T2S PAN 3X6 MFZN 7121300611 1 F53 THERMOSTAT OFF:145 ON:135 V #187 3518903200 1 F54 SCREW TAPPING T1 TRS 4*10 MFZN 7112401011 1 F55 COVER INSULATOR *T SECC T0.5 3511404500 1 F56 SCREW TAPPING T1 TRS 4*10 MFZN 7112401011 1 F57 CLAMP WIRE SBHG 3511200400 1 F58 HEATER 230V 1150W 1B08965001 3512803300 1 F59 SCREW TAPTITE TT3 TRS 4X8 MFZN 7272400811 2 F60 GUIDE AIR OUTLET SA1D-80 T0.5 3512513110 1 F61 NUT HEX 6N-2-5 MFZN 7392500011 1 F62 CAVITY JOINT AS KOC-621Q0S 3516107530 1 F63 REAR-PLATE *O SBHG T0.6 3516503700 1

12. PRINTED CIRCUIT BO ARD

CIRCUIT CHECK PROCEDURE

1. Low voltage transformer check

The low voltage transformer is located on the P.C.B. Measuring condition: Input voltage: 230V / Frequency: 50Hz

2. Voltage Check

- Key check point

- Check method

NOTE

1. Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power source voltage.

2. The allowable tolerance of the secondary voltage is within ± 5% of nominal voltage.

NOTE: Each measure point must be measured with GND points.

Terminal

6-10

Voltage(olad)

DC 13V

Voltage(no load)

DC 14V

NO CHECK POINT REMARK

1 IC1 PIN 55, 64 5VDC±5% 2 IC1 PIN 17

3 IC1 PIN 30 OR 31

T : 20 ms(50Hz)

5V 0V

T : 250 ns(4MHz)

NO MEASURE POINT WAVE FORM REMEDY REMARK

1 A DC 5V±5% Replace C13, C3 NO LOAD 2 B DC 17V±20% Replace D10~D13, EC4 NO LOAD

510

LVT1

DMR-621FS

AS 230V/50Hz

3. Case of no microwave oscillation

1) When touching M/W button, oven lamp turns on and Fan motor and turntable rotate, and cook indicator in display comes on. *Cause: RELAY 1 does not operate.

2) When touching M/W button, oven lamp does not turn on and turntable motor does not rotate but cook indicator in display comes on. *Cause: RELAY 1 does not operate.

3) When touching M/W button, oven lamp turn on and turns on and fan motor does not rotate but cook indicator in display comes on. *Cause: RELAY 6 does not operate.

STATE

RELAY 1 ON

RELAY 1 OFF

POINT A

+5V DC

GND

POINT B

GND

+13V DC

STATE

RELAY 5 ON

RELAY 5 OFF

POINT A

+5V DC

GND

POINT B

GND

+13V DC

STATE

RELAY 6 ON

RELAY 6 OFF

POINT A

+5V DC

GND

POINT B

GND

+13V DC

M/W

RY1

1N4148

G5G-1A-DT 12V

Q10

C106M

LAMP,

TRAY

RY5

D15

1N4148

CS11-12SH 12V

Q7 C106M

FAN

RY6

D16

1N4148

CS11-12SH 12V

Q12

C106M

4. Case of no heating of upper grill

When touching GRILL or COMBI button, oven lamp turns on and Fan motor and turntable rotate, and cook indicator in display comes on. *Cause: RELAY 3 does not operate.

5. Case of no heating of lower grill When touching TEMP button, oven lamp turns on and Fan motor and turntable rotate and cook indicator in display comes on. *Cause: RELAY 4 does not operate.

STATE

RELAY 3 ON

RELAY 3 OFF

POINT A

+5V DC

GND

POINT B

GND

+13V DC

STATE

RELAY 4 ON

RELAY 4 OFF

POINT A

+5V DC

GND

POINT B

GND

+13V DC

UPPER

GRILL

RY3

1N4148

G5G-1A-DT 12V

Q11

C106M

LOWER

GRILL

RY4

D14

1N4148

CS11-12SH- 12V

C106M

6. Case of no stopping of the count down timer

When the door is opened during operation, the count down timer does not stop.

POINT

STATE

DOOR OPEN

DOOR CLOSED

OPEN

+5V DC

GND

CHECK NO METHOD REMEDY

1 Check the stage(ON,OFF) of the door open Replace door open monitor swith.

monitor switch by resistance measurement.

35313-0210

CN1

D.O.M SW

1N4148

R1 1K

10K

+5V

104Z

13. P.C.B. CIRCUIT DIA GRAM

NO NAME SYMBOL SPECIFCATION PART CODE Q'TY

1 BUZZER BZ1 BM-20K 3515600100 1 2 CAPACITOR CERAMIC C1,C3,C8,C9,C13 104 50V Z AXIAL CCZF1H104Z 5 3 CAPACITOR CERAMIC C11,C12 473 50V Z AXIAL CCZF1H473Z 2 4 C ARRAY CA1 1000pF, 2.54MM CN4XB-102M 1 5 CAPACITOR ELECTRO EC2 10V RSS 470uF CEXF1A471V 1 6 CAPACITOR ELECTRO EC3 25V RSS 470uF CEXF1E471V 1 7 CAPACITOR ELECTRO EC4 25V RSS 1000uF CEXF1E102V 1 8 CONNECTOR WAFER CN1 35313-0210 30166M7020 1

9 CONNECTOR WAFER CN2 35312-0310 30166M5030 1 10 CONNECTOR WAFER CN4 FCZ254-8 441M367130 1 11 CONNECTOR WAFER CN5 35328-0610 4CW3061MX0 1 12 DIODE SWITCHING D2,D4,D14~D16 1N4148 AUTO 52mm DZN4148--- 5 13 DIODE SWITCHING D1,D7,D8,D9 1N4148M 5MM DZN4148M-- 4 14 DIODE RECTIFYING D5,D6,D10~D13 1N4004A AUTO 52mm DZN4004A-- 6 15 DIODE ZENER ZD2 UZ -3.9BSB DZUZ3R9BSB 1 16 LED DISPLAY DP1 DDRG-621S-1 DDDRG621S1 1 17 IC MICOM IC1 TMP87CK40AN- 13GS621Q00 1 18 REGULATOR VL1 MC7805C 1CPMC7805C 1 19 PCB MAIN M235 81.5 X 214 3514325200 1 20 RESISTOR R4,R30,R36,R37 1/6W 10K Ohm 5% RD-AZ103J- 4 21 RESISTOR R1,R32,R34 1/6W 1K Ohm 5% RD-AZ102J- 3 22 RESISTOR R40 1/6W 2K Ohm 5% RD-AZ202J- 1 23 RESISTOR R38,R39 1/6W 4.7K Ohm 5% RD-AZ472J- 2 24 RESISTOR R5,R9,R17,R18 1/6W 100K Ohm 5% RD-AZ104J- 4 25 RESISTOR R31 1/6W 1M Ohm 5% RD-AZ105J- 1 26 RESISTOR R33 1/6W 200 Ohm 5% RD-AZ201J- 1 27 RESISTOR R10~R16 1/6W 330 Ohm 5% RD-AZ331J- 7 28 RESISTOR R41~R43 1/2W 27 Ohm 5% RD-2Z270JS 3 29 RESISTOR R6 1/6W 5.88K Ohm 1% RN-AZ5881F 1 30 RESISTOR R7 1/6W 16.9K Ohm 1% RN-AZ1692F 1 31 RESISTOR R8 1/6W 1.30K Ohm 1% RN-AZ1301F 1 32 RESISTOR ARRAY RA1 5P(4) 1/8 100K 5% RA-85X104J 1 33 RESONATOR CERAMIC CR1 CRT-4.00MS 5P4R00MTS- 1 34 SW RELAY RY1,RY3 G5G-1A-DT 12V 5SC0101123 2 35 SW RELAY RY4~RY6 CS11-12SH 5SC0101128 3 36 TRANSISTOR Q8 KTA1266Y AUTO TZTA1266Y- 1 37 TRANSISTOR Q15 KTC3198GR AUTO TZTC3198GR 1 38 TRANSISTOR Q1~Q5 KRA106M AUTO TZRA106M-- 5 39 TRANSISTOR Q6,Q7,Q10~Q13 KRC106M AUTO TZRC106M-- 6 40 TRANS POWER LVT1 DMR-621FS 5EPV041412 1 41 WIRE COPPER 5mm J1,J2,J6,J8,J9 1/0.52 TIN COATING 85801052GY 10

J11~J13,J15.J19 42 WIRE COPPER 10mm J7,J14,J16~J18 1/0.52 TIN COATING 85801052GY 5 43 WIRE COPPER12.5mm J3,J4 1/0.52 TIN COATING 85801052GY 2 44 RESISTOR SJ2 1/6W 1K Ohm 5% RD-AZ102J- 1

PCB ASS’Y PART LIST

S/M NO.:C621Q0S001

DAEW OO ELECTRONICS CO., LTD.

686, AHYEON-DONG MAPO-GU SEOUL, KOREA C.P.O. BOX 8003 SEOUL, KOREA TELEX: DWELEC K28177-8 CABLE: “DAEWOOELEC”

http://www.daewoo.co.kr

PRINTED DATE: DEC. 2001

Daewoo KOC-621Q0S Schematic

Specifications and Main Features

Frequently Asked Questions

User Manual