Daewoo KOC-971C0S User manual

Service Manual
Microwave Oven
Model: KOC-971C0S
KOC-971C2S
KOC-981C1S
KOC-981C2S
DAEWOO ELECTRONICS CO., LTD.
S/M No. : R981C0S001

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  
    
  
   
    
    
  
   
    
     
 ! !  
    "
        
        
     
     
! !  #
 !  
      
 !   
 !   
 !   #
  !  $
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 allovens to be serviced before activating the magnetron or other microwave
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.
(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, oradjusted by procedures described in this manualbefore the
oven is released to the owner.
(e)A microwave leakage check to verifycompliance with the Federal performance standardshould be performed on
each oven prior to release to the owner.


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 doorhinge.
(2) A broken doorviewing screen.
(3) A broken front panel, oven cavity.
(4) A loosened door lock.
(5) A broken doorlock.
The door gasket plate and ovencavity surface should be kept clean.
No grease, soil or spatter should be allowed to build up on these surfacesor inside the oven.
DO NOTATTEMPT TO OPERATE THIS APPLIANCE WITH THE DOOROPEN.
The microwave oven has concealed switches to make sure the poweris turned off when the door is opened.
Do not attempt to defeat them.
DO NOTATTEMPT TO SERVICE THIS APPLIANCE UNTIL YOU HAVE READ THIS SERVICE MANUAL.
2. FOR SAFE SERVICE PROCEDURES
1. If the oven is operative priorto 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 emissioncheck 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.
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 terminalin the plug which is marked with the
letter 'E',earth symbolor 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 terminalwhich is marked with the letter 'L'or coloured red.
IMPORTANT
This oven is designed for counter-top use only.
NOTE


SPECIFICATIONS
SPECIFICATIONS ARE SUBJECTTO CHANGE WITHOUTNOTICE.
MODEL KOC-971C0S KOC-971C2S
POWER SUPPLY 230V~50Hz 230V~50Hz
POWER CONSUMPTION
MICROWAVE 1450W 1450W
GRILL 1200W 1200W
CONVECTION 1550W 1550W
PROGRAM COOK 1850W 1850W
COMBINATION 2600W (Simultaneous) 1550W (Sequential)
MICROWAVE ENERGY OUTPUT 950W(IEC705) 950W(IEC705)
MICROWAVE FREQUENCY 2450MHz 2450MHz
OUTSIDE DIMENSIONS (W X H X D) 526 x 345 x 387 mm (20.7 x 13.6 x 15.2 in.)
CAVITY DIMENSIONS (W X H X D) 335 x 255 x 339 mm (13.2 x 10.0 x 13.3 in.)
NET WEIGHT APPROX.20 Kg (44.2 lbs.)
TIMER 60 minutes
FUNCTION SELECTIONS MICROWAVE/GRILL/CONVECTION/COMBI
POWER SELECTIONS 10 LEVELS
CAVITY VOLUME 1.0 Cu.Ft.
MODEL KOC-981C1S KOC-981C2S
POWER SUPPLY 230V~50Hz 230V~50Hz
POWER CONSUMPTION
MICROWAVE 1450W 1450W
GRILL 1200W 1200W
CONVECTION 1550W 1550W
PROGRAM COOK 1850W 1850W
COMBINATION 2600W (Simultaneous) 1550W (Sequential)
MICROWAVE ENERGY OUTPUT 1000W(IEC705) 1000W(IEC705)
MICROWAVE FREQUENCY 2450MHz 2450MHz
OUTSIDE DIMENSIONS (W X H X D) 526 x 345 x 455 mm (20.7 x 13.6 x 17.9 in.)
CAVITY DIMENSIONS (W X H X D) 335 x 250 x 339 mm (13.2 x 9.8 x 13.3 in.)
NET WEIGHT APPROX.21 Kg (46.3 lbs.)
TIMER 60 minutes
FUNCTION SELECTIONS MICROWAVE/GRILL/CONVECTION/COMBI
POWER SELECTIONS 10 LEVELS
CAVITY VOLUME 1.0 Cu.Ft.


EXTERNAL VIEW
1. OUTER DIMENSION
KOC-971C
KOC-981C


EXTERNAL VIEW
2. FEATURE DIAGRAM
KOC-971C
1.Door seal - Door seal maintains the microwave energy within the oven cavity and prevents microwave leakage.
2.Door hook - When the door is closed, it will automatically shut. Ifthe door is opened while the oven is operating,
the magnetron will immediately stop operating.
3.Door viewing screen - Allowsviewingoffood.Thescreen is designedso thatlightcanpassthrough, but not the microwave.
4.Top heater - Turnson when convection,grill and combi cooking is selected.
5.Oven lamp - Automatically turns on during oven operating.
6.Safety interlock system
7.Control panel
8.Turntable tray - Rotates during cooking and ensure even distribution of Microwaves.
It can also be used as a cooking utensil.
9.Oven front plate
10.Rotating base - This fits over the shaft in thecenter of the ovens cavity floor.
This is to remain in the oven for all cooking. It should only be removed for cleaning.
11. Under heater
12.Door opening button - To open the door, push the door opening button.


EXTERNAL VIEW
KOC-981C
1.Door seal - Door seal maintains the microwave energy within the oven cavity and prevents microwave leakage.
2.Door hook - When the door is closed, it will automatically shut. Ifthe door is opened while the oven is operating,
the magnetron will immediately stopoperating.
3.Door viewing screen - Allowsviewingoffood.Thescreen is designedso thatlightcanpassthrough, but not the microwave.
4.Top heater - Turnson when convection,grill and combi cooking is selected.
5.Oven lamp - Automatically turns on during oven operating.
6.Safety interlock system
7.Control panel
8.Turntable tray - Rotates during cooking and ensure even distribution of Microwaves.
It can also be used as a cooking utensil.
9.Oven front plate
10.Rotating base - This fits over the shaft in thecenter of the ovens cavity floor.
This is to remain in the oven for all cooking. It should only be removed for cleaning.
11. Under heater
12.Metal rack
13.Convection Outlet & Fan
14.Door openning button - To open the door, push the door openingbutton.


INSTALLATION
1. Steady, flat location
This microwave oven should be set on a steady, flat surface.
This microwave oven is designed forcounter 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 resultif the oven is located close to a TV, radio,antenna or feeder and so on.
Position the oven as far from them aspossible.
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. Thismicrowave oven requires a current of approximately 13amperes, 230 Volts, 50 Hz.
Power supply cord is about 1.2 meters long.
The voltage used must be the same asspecified on this oven. Using a higher voltage may result in afire 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 cableof 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 iscolder 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 electricshock bypro-
viding an escape wire for the electric current. Thisappliance is equipped with
acordhaving a earthing wire withaearthing plug. The plug mustbepluggedinto an outletthatisproperlyinstalledandearthed.
EARTHINGINSTRUCTIONS
Improper use of the earthing plug can result in a risk ofelectric shock.
Consult a qualified electrician or 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 ofthe extension cord should be equalto or greater than the electrical rating of the appliance,
or Do not use an extension cord.
WARNING


CONTROL PANEL
PROGRAM
MW GLILL WEIGHT - TIMECOMBI
COOK PIE TEMP
COOK KG
DEFROST
When blinking, the oven is
operating in "COMBI"
cooking mode.
When blinking, the oven is
operating in "GRILL"
cooking mode.
operating in "MICROWAVE"
When blinking, the oven is
cooking mode.
operating in "PROGRAM COOK"
cooking mode.
When blinking, the oven is
When blinking, the oven is
operating in "PIE"
cooking mode.
operating in "CONVECTION"
When blinking, the oven is
cooking mode.
When blinking,the oven is
operating in "WEIGHT
DEFROST"cooking mode.
mode.
operating in weght input
When blinking,the oven is
operating in "TIME
When blinking,the oven is
DEFROST"cooking mode.
Used to select the variable
Microwave Power Level-
microwave power level. If
this button is pressed for
more than 1.3 sec, number
is scrolled up automatically.
is pressed for more than
scrolled up automatically.
1.3 sec, number is
temperature. If this button
Temperature Pad-
Used to set desired
cooking function.
Used to select desired
Function Pads-
M/W : MICROWAVE
GRILL
DEFROST : TIME or WEIGHT
DEFROST
TEMP :CONVECTION
COMBI : COMBINATION
PIE
PROGRAM COOK
cooking time in 30 sec
Used to program quickly
Speedy Cook Pad-
increments.
the time of day.
Clock Pad-
Used to set and recall
all information manually
Used to pause and clear
Stop/Clear Pad-
put into the oven.
cooking cycle.
Used to start the selected
Start Pad-
3. Roast Chicken
2. Roast Pork
1. Roast Beef
5. Vegetable
4. Fish Fillet
GRILL COMBI
M/W TEMP
DEFROST
PIE
Weight/Time
PROGRAM
COOK
SPEEDY COOK
STOP/ START
CLEAR
10min
1Kg 1min 0.1Kg 10sec
Numerals are used to enter
the cooking time and/or time
of day and weight input.
Used to open the door.


DISASSEMBLY ANDASSEMBLY
Cautions to be observed when trouble shooting.
Unlike many other appliances, the microwave oven is high-voltage, high-current equipment.
It is completely safety 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 observethe following precautions carefully.
1. Always remove the powerplug from the outlet before servicing.
2. Use an insulated screwdriver and ware rubber gloves when servicing the high voltage side.
3. Discharge the high voltage capacitor before touching any oven components or wiring.
(1) Check the earthed.
Do not operate on a two-wire extension cord.
The microwave oven is designed to be used with 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 stopped and electric charge
remains in the high voltage capacitor.
When replacing or checking parts, shortbetween oven chassis and
the negative high terminal of the high voltage capacitor,
by using a properly insulated screwdriver to discharge.
4. When the15A fuseis blownout due to theoperationof themonitor switch;
replace primary interlock switch, secondary interlock
switch and interlock monitor switch.
5. After repair or replacementof parts, make surethat the screws are
properly tightened, and all electrical connections are tightened.
6. Do not operate without cabinet.
Service personnel should remove their watches whenever working close to or replacing the magnetron.
CAUTION
When servicing the appliance,needa care oftouching orreplacing high potentialparts becauseofelectricalshock or
exposing microwave. These parts are as follows - HV Transformer, Magnetron, HV Capacitor, HV Diode.
WARNING


DISASSEMBLY ANDASSEMBLY
1. To remove cabinet
(1) Remove four screws on cabinetback.
(2) Push the cabinet backward.
2. To remove guide wind assembly
(1) Remove two screws for earthingand for fixing to rear-plate.
(2) Remove the noise filter from theguide wind.
(3) Pull the fan from the motor shaft.
(4) Remove two screws which secure the motor shaded pole.
(5) Remove the motor shaded pole.
(6) Reverse the above steps for reassembly.


DISASSEMBLY AND ASSEMBLY
3. To remove H.V.transformer
(1) Remove four screws which secure
the H.V.transformer to the base plate.
(2) Remove the H.V.transformer.
(3) Reverse the above steps for reassembly.
4. To remove high voltage capacitor
(1) Remove a screw which securethe 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


DISASSEMBLY ANDASSEMBLY
5. To remove magnetron
(1) Remove three screws which secure the magnetron.
(2) Remove the magnetron.
(3) Reverse the above steps for reassembly.
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
2
for a fully assembled oven with door normally closed.
CAUTION


DISASSEMBLY AND ASSEMBLY
6. To remove control panel assembly
(1) Remove a screw which securethe control panel assembly to
the oven front plate.
At the same time, draw forward the control panel assembly
from the oven front plate.
(2) Disconnect membrane tail from the connector of the
PCB main assembly.
(3) Remove three screws which secure the
PCB main assembly to control panel.
REF NO. PART CODE PART NAME DESCRIPTION QTY REMARK
B01 3516715100 CONTROL-PANEL ABS 1
B02 441B655072 SPRING DOOR BUTTON HSWR 1
B03 3516905010 BUTTON DOOR OPEN ABS 1
B04 3518518200 SWITCH MEMBRANE KOC-971C/981C 1
B05 PKMPMSQ100 PCB MAIN AS KOC-971C0S/971C2S 1PKMPMSQ150 PCB MAIN AS KOC-981C1S
PKMPMSQ160 PCB MAIN AS KOC-981C2S
B06 7S341W40B1 SCREW SPECIAL
T2S PAN 4X12 PW SE MFZN 3
B07 3513702300 LEVER DOOR OPEN POM 1


DISASSEMBLY ANDASSEMBLY
7. To remove door assembly
(1) Remove two screws which secure the stopper hinge top.
(2) Remove the door assembly fromtop plate of cavity.
(3) Reverse the above steps for reassembly.
8. To remove door parts
(1) Remove the gasket door.
(2) Remove the door seal ass’y.
(3) Remove the hook and spring.
(4) Remove the barrier-screen *o.
REF. NO. PART CODE PART NAME DESCRIPTION QTY REMARK
A01 3511708400 DOOR SEAL AS KOC-971C0S 1
A02 3513100900 HOOK POM 1
A03 3515101300 SPRING HOOK PW1 1
A04 3517004000 BARRIER-SCREEN *O TEMPERED GLASS T3.2 1
A05 3512203300 FRAME DOOR ABS XR-401 1
A06 3512300800 GASKET DOOR PBT 1
A07 3515203600 STOPPER HINGE *T AS KOC-970T1S 1
After replacing the door assembly, perform a check of
correct alignment with the hinge and cavity front plate.
NOTE


DISASSEMBLY AND ASSEMBLY
9. 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 sealto 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 sealto oven front surface.
• Tighten two screws.
(3) To reduce gap located on part ‘C’
• Loosen a screw on interlock switchassembly
located bottom of oven body.
• Draw the interlock switch assembly inward as possible to engage with hook on the door bottom.
• Tighten a screw.
(4) To reduce gap located on part ‘D’
• Loosen a screw on interlock switchassembly located top of oven body.
• Following steps are same as step (3).
Small gap may be acceptable if the microwave leakage does not exceed 1mW/cm
2
.
NOTE
The door on a microwave oven is designed to act as an electronic seal preventing the leakage of microwave energy
from the oven cavity during the cook cycle.This function does not require that the door be air-tight, moisture (conden-
sation) Tight or light-tight. Therefore, the occasionalappearance of moisture, light or the sensing of gentle warm air
movement around the oven door is not abnormal and do not of themselves, indicate a leakage of microwave energy
from the oven cavity. If such were the case, your oven could not be equipped with a bent, the very purpose of which
is to exhaust the vapor-laden air from the oven cavity.
NOTE


DISASSEMBLY ANDASSEMBLY
10. To remove motor syncro and under heater
(1) Cut the syncro motor cover partsfrom the base plate.
(2) Remove two screws which secure the motor syncro and supporter to bracket syncro motor.
(3) Remove two screws and under heater assembly in cavity
11. To remove grill heater assembly
KOC-971C
(1) Remove a nut which secure the heater holder inserting the wire of grill heater to side plate.
(2) Remove two nuts and a screw which secure the heater bracket to grill heater.
(3) Remove two heater brackets.
(4) Pull the heater holder inward and then remove the grillheater.
(5) Reverse the above steps for reassembly.


DISASSEMBLY AND ASSEMBLY
KOC-981C
(1) Remove two screws which secure the cover insulator *t to top plate.
(2) Remove the harness between heaters.
(3) Remove two screws for removing heater brackets.
(4) Remove heaters.
(5) Reverse the above steps for reassembly.
12. To remove convection part assembly (KOC-981C only)
(1) Remove cover *b and cover insulator *b protecting convection part assembly. - release two lances ofcover insulator *b.
(2) Remove four screws which secure the convection part assembly to the cavity rear plate.
(3) Remove a nut holding the convection fan and the pipe.
(4) Remove two screws which secure the bracket motor to cover insulator.
(5) Remove the cooling fan.
(6) Remove two screws which secure the motor shaded pole to the bracket motor.
(7) Reverse the above steps for reassembly.


INTERLOCK MECHANISM AND ADJUSTMENT
The door lock mechanism is adevice 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, door open monitor switch and interlockmonitor switch
When the door is closed, the hook pushes the latch lever downward.
The latch lever presses the button of the interlock monitor switch to bring it under “OFF” condition and
presses the button of the secondary interlock switch and door open monitor switch to bring it under “ON” condition.
3. Adjustment steps
(1) Loosen two mounting screws.
(2) Adjust interlock switch assembly position.
(3) Make sure that latch lever movessmoothly after adjustment is completed.
(4) Tighten completely two mounting screws.
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.
ADJUSTMENT
Microwave emission test should be performed after adjusting interlock mechanism.
If the microwave emission exceed 4mW/cm2, readjust interlockmechanism.
NOTE


TROUBLE SHOOTING GUIDE
Following the procedures below to check if the oven is defective or not.
1. Check grounding before checking trouble.
2. Be careful of the high voltagecircuit.
3. Discharge the high voltage capacitor.
4. When checking the continuityof the switches, fuse or high voltage transformer, disconnect one lead wire from these parts
and then checkcontinuity with theAC plugremoved. To do otherwise may resultin afalse reading or damageto yourmeter.
(TROUBLE 1) Oven does not operate at all; any inputs can not be accepted.
When electric parts are checked, be sure the power cord is not inserted into the wall outlet.
Check wire harness, wiring, and connected of the terminals and power cord before check parts listed below.
NOTE
CONDITION
CHECK RESULT CAUSE REMEDY
Fuse blows. Continuity
(COM NC)

(COM NC)

No Continuity
No
Continuity
Continuity
Continuity
0 infinite
Ω
or
Approx.
150~210
(normal)
Fuse again
blows
Replace
NOTE 1
Replace
NOTE 1
Replace
NOTE 1
Replace
Replace
Check continuity of
interlock monitor switch
with door closed
(COM NC)

Check continuity of both
primary and secondary
interlock switch with
door closed
Check continuity of
primary winding of low
voltage transformer
Disconnect high voltage
fuse and operate the unit
Check continuity of
primary interlock switch
contact with door
partially open until
interlock monitor switch
contact close
(COM NC close)

Malfunction
of interlock
monitor
switch
Malfunction
of interlock
switch
Shorted
contacts of
primary
interlock
switch
Defective low
voltage
transformer
Defective
high voltage
transformer