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S/M No. : C922T9S001
Service Manual
Microwave Oven
Model: KOC-922T9S
KOC-922T9R
KOC-923T9S
KOC-923T9R
Caution
: In this Manual, some parts can be changed for improving,
their performance without notice in the parts list. So, if you
need the latest parts information, please refer to PPL(Parts
Price List) in Service Information Center (http://svc.dwe.co.kr).
DAEWOO ELECTRONICS CORP.
http : //svc.dwe.co.kr Oct. 2003
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.
TABLE OF CONTENTS
1. SAFETY AND PRECAUTIONS....................................................................................................................................2
2. SPECIFICATIONS ........................................................................................................................................................3
3. EXTERNAL VIEW.........................................................................................................................................................4
3-1. OUTER DIMENSION ..........................................................................................................................................4
3-2. FEATURE DIAGRAM .........................................................................................................................................5
4. INSTALLATION ............................................................................................................................................................6
5. CONTROL PANEL .......................................................................................................................................................7
6. DISASSEMBLY AND ASSEMBLY ..............................................................................................................................9
7. INTERLOCK MECHANISM AND ADJUSTMENT.....................................................................................................19
8. TROUBLE SHOOTING GUIDE ..................................................................................................................................20
9. MESUREMENT AND TEST .......................................................................................................................................25
9-1. MEASUREMENT OF THE MICROWAVE POWER OUTPUT ........................................................................25
9-2. MICROWAVE RADIATION TEST ....................................................................................................................26
9-3. COMPONENT TEST PROCEDURE................................................................................................................27
9-4. COMPONENT ACTION....................................................................................................................................28
10. WIRING DIAGRAM...................................................................................................................................................29
11. EXPLODED VIEW AND PARTS LIST .....................................................................................................................30
11-1. DOOR ASSEMBLY.........................................................................................................................................30
11-2. CONTROL PANEL ASSEMBLY.....................................................................................................................30
11-3. TOTAL ASSEMBLY........................................................................................................................................30
12. PRINTED CIRCUIT BOARD ....................................................................................................................................33
13. P.C.B CIRCUIT DIAGRAM.......................................................................................................................................39
1
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.
2
2. SPECIFICATIONS
MODEL KOC-922T9S/923T9S
POWER SUPPLY 230V~50HZ, SINGLE PHASE WITH EARTHING
MICROWAVE 1500W
POWER GRILL 1150W
CONSUMPTION CONVECTION 2550W
COMBINATION 3000W
MICROWAVE ENERGY OUTPUT 1000W(IEC705)
MICROWAVE FREQUENCY 2450MHz
OUTSIDE DIMENSIONS (W X H X D) 542X329X503mm (21.3X13.0X19.8 in.)
CAVITY DIMENSIONS (W X H X D) 350X230X355mm (13.8X9.1X14.0 in.)
NET WEIGHT APPROX. 20kg (44.1 lbs.)
TIMER 60 minutes
FUNCTION SELECTIONS MICROWAVE / GRILL / CONVECTION / COMBINATION
POWER SELECTIONS 10 LEVELS
CAVITY VOLUME 1.0 Cu. Ft
MODEL KOC-922T9R/923T9R
POWER SUPPLY 230V~50HZ, SINGLE PHASE WITH EARTHING
MICROWAVE 1500W
POWER GRILL 1150W
CONSUMPTION CONVECTION 1450W
COMBINATION 1500W
MICROWAVE ENERGY OUTPUT 1000W(IEC705)
MICROWAVE FREQUENCY 2450MHz
OUTSIDE DIMENSIONS (W X H X D) 542X329X503mm (21.3X13.0X19.8 in.)
CAVITY DIMENSIONS (W X H X D) 350X230X355mm (13.8X9.1X14.0 in.)
NET WEIGHT APPROX. 20kg (44.1 lbs.)
TIMER 60 minutes
FUNCTION SELECTIONS MICROWAVE / GRILL / CONVECTION / COMBINATION
POWER SELECTIONS 10 LEVELS
CAVITY VOLUME 1.0 Cu. Ft
* Specifications are subject to change without notice.
3
3. EXTERNAL VIEW
1. OUTER DIMENSION
542 503
329
4
2. FEATURE DIAGRAM
2 34 56
7
1
e w q 09 8
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.METAL RACK
14.TOP HEATER
Turns on when convection, grill and combi cooking is selected.
15.OVEN LAMP
Automatically turns on during oven operating.
16.SAFETY INTERLOCK SYSTEM
17.CONTROL PANEL
18.TURNTABLE TRAY
Rotates during cooking and ensure even distribution of Microwaves.
It can also be used as a cooking utensil.
19.ROLLER GUIDE
This must always be used for cooking together with the turntable tray.
10. COUPLER
This fits over the shaft in the center of the ovens cavity floor. This is to remain in the oven for all cooking.
11. CONVECTION OUTLET & FAN
12. OVEN FRONT PLATE
13.DOOR SEAL
Door seal maintains the microwave energy within the oven cavity and prevents microwave leakage.
5
4. INSTALLATION
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 15(KOC-922T9S/923T9S)
12(KOC-922T9R/923T9R) 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.
EARTHING INSTRUCTIONS
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.
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.
6
5. CONTROL PANEL
KOC-922T9S, KOC-922T9R
1 Display : Cooking time, power level, indicators and
present time are displayed.
MW : When blinking, the oven is operating in
MICROWAVE COOK.
Grill : When blinking, the oven is operating in GRILL.
Combi : When blinking, the oven is operating in
COMBI.
Defrost Weight : When blinking, the oven is
operating in WEIGHT DEFROST.
Time : When blinking, the oven is operating in TIME
DEFROST.
Auto-cook : When blinking, the oven is operating
AUTO COOK.
Lock : When lighting, the oven is CHILD LOCK.
Con-vection : When blinking, the oven is operating
in CONVECTION.
g : When blinking, the oven is operating in weight
input mode.
2 Auto cook : Used to cook or reheat.
1. Roast pork 2. Roast beef 3 Clock : Used to set clock.
3. Roast chicken 4. Baked fish 5. Fresh vegetable
4 Time Defrost : Used to defrost foods.
5 Weight Defrost : Used to defrost foods.
6 MW : Used to set power level of micro wave.
7 Convection : Used to select convection and selected
temp.
8 Combi : Used to select combi.
9 Grill : Used to select grill.
0 Dial knob : Used to set time, weight and quantity.
q START/SPEEDY COOK : Used to start a
programmed, also for speedy start(each press adds
30 seconds microwave cooking time).
w STOP/CLEAR : Used to stop the oven operation or
to delete the cooking data.
7
KOC-923T9S, KOC-923T9R
1 Display : Cooking time, power level, indicators and
present time are displayed.
MW : When blinking, the oven is operating in
MICROWAVE COOK.
Grill : When blinking, the oven is operating in GRILL.
Combi : When blinking, the oven is operating in COMBI.
Defrost Weight : When blinking, the oven is
operating in WEIGHT DEFROST.
Time : When blinking, the oven is operating in TIME
DEFROST.
Auto-cook : When blinking, the oven is operating
AUTO COOK.
Lock : When lighting, the oven is CHILD LOCK.
Con-vection : When blinking, the oven is operating
in CONVECTION.
g : When blinking, the oven is operating in weight
input mode.
2 Auto cook : Used to cook or reheat.
3 Combi : Used to select combi.
4 Convection : Used to select convection and
selected temp.
5 MW : Used to set power level of micro wave.
6 Grill : Used to select grill.
7 Time Defrost : Used to defrost foods.
8 Weight Defrost : Used to defrost foods.
9 Clock : Used to set clock.
0 Pizza : Used to cook or reheat pizza.
q Time set pad : Used to set time, weight and quantity.
w START/SPEEDY COOK : Used to start a
programmed, also for speedy start(each press adds
30 seconds microwave cooking time).
e STOP/CLEAR : Used to stop the oven operation or
to delete the cooking data.
8
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 20A 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.
9
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.
NOTE: After replacing the door assembly, perform a check
of correct alignment with the hinge and cavity front
plate.
10
3. To remove door parts.
REF NO. PART CODE PART NAME DESCRIPTION Q TY REMARK
A01 3512204830 FRAME DOOR ABS SR-0320 1
A02 3517007150 BARRIER-SCREEN*0 GLASS T3.2 MIRROR 1
A03 3515304800 SUPPORTER HINGE*T SCP-1 T2.0 1
A04 3516602200 DOOR PLATE SBHG-3A T0.7 1
A05 3517007000 BARRIER-SCREEN*I TEMP GLASS T2.0 1
A06 3512302400 GASKET DOOR PBT 1
A07 3513101200 HOOK POM 1
A08 3515101800 SPRING HOOK PW1 1
11
(1) Remove the gasket door from door plate.
(2) Remove the door frame from door plate.
(3) Remove the stopper hinge top from door plate.
(4) Remove the spring and the hook.
(5) Remove the barrier screen outer from door frame.
(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.
NOTE : A small gap may be acceptable if the microwave leakage does not exceed 4mW/cm2.
12
Caution : In this Manual, some parts can be changed for improving, their performance without notice in the
parts list. So, if you need the latest parts information, please refer to PPL(Parts Price List) in Service
Information Center (http://svc.dwe.co.kr).
5. To remove control panel parts.
REF NO. PART CODE PART NAME DESCRIPTION Q'TY REMARK
B01 3515501320 WINDOW DISPLAY SAN 1
B02 3516725230 CONTROL-PANEL ABS SR-0320 1
B03 3516911900 BUTTON FUNCTION-A ABS SR-0760D SPRAY 1
B04 3516909970 BUTTON FUNCTION-C ABS SR-175 SG-0760D SPRAY 1
B05 3516909960 BUTTON FUNCTION-B ABS SR-175 SG-0760D SPRAY 1
B06 3513406600 KNOB VOLUME ABS SR-175 SG-0760D 1
B07 PKMPMSYQ00 PCB MAIN MANUAL AS KOC-922T9S 1 922T9S
PKMPMSYQ10 KOC-922T9R 922T9R
B08 7121301011 SCREW TAPPING T2S PAN 3X10 MFZN 7
B09 PKBPMSYQ00 PCB BUTTON MANUAL AS KOC-922T9S 1
B10 7122401211 SCREW TAPPING T2S TRS 4X12 MFZN 4
B11 3516909980 BUTTON FUNCTION-D ABS SG-175 SG-0760D SPRAY 1
(1) Remove the screw which secure the control panel, push up two snap fits and draw forward the control panel assembly.
(2) Remove four screws(B10) which secure the PCB Main ASS'Y.
(3) Pull out the Main PCB assembly(B09).
(4) Remove seven screws(B08) which secure the PCB Sub ASS'Y.
(5) Pull out the Sub PCB assembly(B07).
(6) Pull out the Knob volume(B06) from the Sub PCB assembly.
(7) Pull out buttons from the control panel.
(8) Pull out Window display(B01) from the control panel.
(9) Reverse the above steps for reassembly.
13
Caution : In this Manual, some parts can be changed for improving, their performance without notice in the
parts list. So, if you need the latest parts information, please refer to PPL(Parts Price List) in Service
Information Center (http://svc.dwe.co.kr).
REF NO. PART CODE PART NAME DESCRIPTION Q'TY REMARK
B01 3518524300 SWITCH MEMBRANE KOC-923T9S 1
B02 3516725250 CONTROL-PANEL ABS SR-0320 1
B03 PKMPMSAS00 PCB MAIN MANUAL AS KOC-923T9S 1 923T9S
PKMPMSAS10 KOC-923T9R 923T9R
B04 7122401211 SCREW TAPPING T2S TRS 4X12 MFZN 4
(1) Remove the screw which secure the control panel, push up two snap fits and draw forward the control panel assembly.
(2) Remove four screws which secure the PCB assembly to control panel.
(3) Disconnect membrane tail from the connector of the PCB assembly.
(4) Detach membrane from the control panel.
(5) Reverse the above steps for reassembly.
14
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.
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/cm2 for a fully assembled oven with door normally closed.
Metallic Magnetron
gasket antenna
plate
Cooling fin
Filament
terminal
15
8. To remove wind guide assembly.
1) Remove a screw for earthing.
2) Remove the noise filter from the wind guide.
3) Remove a screw 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.
16
Caution : In this Manual, some parts can be changed for improving, their performance without notice in the
parts list. So, if you need the latest parts information, please refer to PPL(Parts Price List) in Service
Information Center (http://svc.dwe.co.kr).
10. To remove Top heater assembly parts.
5
6
7
1
8 2
3
4
REF NO. PART CODE PART NAME DESCRIPTION Q TY REMARK
1 7112401011 SCREW TAPPING T1 TRS 4X10 MFZN 1
2 3512520500 GUIDE AIR OUTLET SA1D T0.5 1
3 3513303000 INSULATOR HEATER*T SECC T0.5 1
4 7112401011 SCREW TAPPING T1 TRS 4X10 MFZN 2
5 3512767000 HARNESS HEATER KOC-1B0K0S 1
6 3510607700 BRACKET HEATER *T SA1D T0.5 1
7 3512803800 HEATER MIRACLON 115V 550W 270MM 2
8 3511407600 COVER HEATER *T STS430 T0.5 1
1) Remove a screw 1 and pull out Guide air outlet 2.
2) Remove two screws4 and pull out insulator heater *t3.
3) Pull out the Top heater assembly.
4) Pull out the Harness heater5.
5) Pull out the Braket heater*t from the Cover heater*t8.
6) Pull out the Heater miraclon7 from the Cover heater*t8.
7) Reverse the above steps for reassembly.
17
Caution : In this Manual, some parts can be changed for improving, their performance without notice in the
parts list. So, if you need the latest parts information, please refer to PPL(Parts Price List) in Service
Information Center (http://svc.dwe.co.kr).
11. To remove Rear heater assembly parts.
14 15 16 17 1
13 12 11 10 9 8 7 6 5 4 3 2
REF NO. PART CODE PART NAME DESCRIPTION Q TY REMARK
1 3511407300 COVER MOTOR*B SA1D-80 T0.5 1
2 7112401011 SCREW TAPPING T1 TRS 4*10 MFZN 1
3 7112401011 SCREW TAPPING T1 TRS 4*10 MFZN 1
4 3511407900 COVER*B SA1D-80 T0.5 1
5 3512767600 HARNESS CONVECTION KOC-924T0S 1
6 7113400814 SCREW TAPPING T1 BIN 4*8 MFNI 4
7 3511409800 COVER HEATER*B SA1D-80 T0.5 1
8 3513303400 INSULATOR HEATER*B SBHG-1 T0.5 1
9 7113400814 SCREW TAPPING T1 BIN 4*8 MFNI 3
10 3511800700 FAN CONVECTION SA1D-80 T0.5 1
11 3513002300 HOLDER HEATER SUS430 T-.5 3
12 3512801800 HEATER 230V 1400W 1R18344 1
13 7400104011 WASHER PLAIN PW-1-4 MFZN 1
14 7051400811 SCREW MACHINE PAN 4*8 SW MFZN 2
15 3963514300 MOTOR SHADED POLE 230V 50HZ MW10CA-T02 1
16 3511800800 FAN P.P GF20 1
17 7402704600 RING C CR-5 SK5 1
1) Remove a screw 1 and pull out Cover motor *B2.
2) Remove a screw 3 and pull out Cover *B4.
3) Pull out the Harness convection-B 5.
4) Remove four screws 6 and then pull out the Rear heater assembly.
5) Remove a Nut e and the pull out the Fan convection 0.
6) Remove three screws 9 and then separate the Cover heater *B 7 and the lnsulator heater *B8.
7) Pull out the Heater w from the Cover Heater *B 7.
8) Remove two screw r and then separate the lnsulator heater *B 8 and Motor shaded polet.
9) Remove the C-Ring u and then pull out the Fan y from Motor shaft.
10)Reverse the above steps for reassebly.
18
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.
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.
(3) Adjustment steps
a) Loosen the one mounting screw.
b) Adjust interlock switch assembly position.
c) Make sure that lock lever moves smoothly after adjustment is completed.
d) Tighten completely two mounting screws.
NOTE :
Microwave emission test should be performed after adjusting interlock mechanism.
If the microwave emission exceed 4mW/cm2, readjust interlock mechanism.
19
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.
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.
(TROUBLE 1) Oven does not operate at all : any inputs can not be accepted.
CONDITION CHECK RESULT CAUSE REMEDY
Fuse blows. Continuity Replace
Check continuity of Malfunction of
interlock monitor switch with Interlock
door closed (COM NC) monitor switch
( COM NC ) No continuity
No Replace
Check continuity of Malfunction of
both primary and secondary Continuity
interlock switch
interlock switch with door closed
Continuity
Continuity Replace
Check continuity of Shorted contacts
primary interlock switch contact of primary
with door partially open until interlock Switch
interlock monitor switch contact
close
( COM NC close )
or infinite Replace
Check continuity of Defective low
primary winding of low voltage voltage
transformer Approx. transformer
480 ~620
( normal )
Disconnect high voltage Fuse again Defective Replace
fuse and operate the unit blows high voltage
transformer
20
CONDITION CHECK RESULT CAUSE REMEDY
Outlet has Check continuity of No Defective
Replace
proper magnetron continuity magnetron.
voltage
fuse does not
blow? Check continuity of noise filter No Defective line
Replace
board continuity filter board
Check continuity of No Open power Replace
power supply cord continuity supply cord
No Defective touch
Replace
continuity control circuit
NOTE : All these switches must be replaced at the same time, please refer to (7.Interlock mechanism and
adjust) 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 RESULT CAUSE REMEDY
Turn table Check continuity of No Malfunction of Adjust or
motor and primary interlock switch continuity primary interlock replace
oven lamp switch
do
not turn on Check continuity of No Malfunction of Adjust or
secondary interlock continuity secondary replace
and D.O.M switch Interlock and
D.O.M switch
Check D.C voltage Defective touch Replace
0V
being supplied to control Circuit
RELAY(RY4) coil
Approx. Fault contacts Replace
24V DC of RELAY
(RY4) or open
relay coil.
21
TROUBLE 3) No microwave oscillation even though fan motor rotates.
CONDITION CHECK RESULT CAUSE REMEDY
No Check continuity of No Defective Replace
microwave high voltage fuse continuity high voltage
oscillation fuse
No microwave oscillation
Check continuity of Continuity Defective 1
high voltage capacitor terminals high voltage
with wires removed transformer
Check continuity of Continuity Defective high Replace
high voltage rectifier in forward in backward voltage rectifier
and backward direction
direction with DC megger
Connect megger leads to Continuity Defective 2
magnetron terminal and magnetron
magnetron body
Check D.C voltage 0V Defective Replace
being supplied to touch control
RELAY (RY1) coil circuit
Approx. Faulty contacts of Replace
24V DC RELAY
(RY1) or open
relay coil
1 Check resistance of primary 0 or Defective Replace
and secondary coil of high high voltage
voltage transformer transformer
1 Check continuity of filament No continuity Defective high Replace
terminal of high voltage voltage
transformer transformer
2 Check continuity of Defective Replace
No continuity
magnetron heater with wires magnetron
removed
22
(TROUBLE 4)
Grill heater (upper heater) is not heated; food will not become hot.
CONDITION CHECK RESULT CAUSE REMEDY
Check continuity of No Malfunction of Adjust or
Grill heater is continuity primary Interlock replace
primary interlock switch
not heated. switch
Check continuity of No Malfunction of Adjust or
secondary interlock switch continuity secondary replace
interlock switch
Check continuity of No Replace
Defective heater
heater continuity
Check D.C voltage 0V Defective touch Replace
being supplied to control circuit
RELAY (RY2) coil
Approx. Faulty contacts of Replace
24V DC RELAY
(RY2) or open
relay coil
(TROUBLE 5)
1) Convection heater is not heated; food will not become hot.
2) Convection fan motor does no rotate.
CONDITION CHECK RESULT CAUSE REMEDY
1)Convection Check continuity of No Malfunction of Adjust or
heater is not primary interlock switch continuity primary Interlock replace
heated. switch
2)Convection
fan and Check continuity of No Malfunction of Adjust or
motor does secondary interlock continuity secondary replace
not rotate. switch interlock switch
Check continuity of No Replace
Defective motor
(heater or motor) continuity
Check D.C voltage 0V Defective touch Replace
being supplied to control circuit
RELAY (RY3, RY6) coil
Approx. Faulty contacts of Replace
24V DC RELAY
(RY3,RY6) or
open relay coil
23
(TROUBLE 6)
The following visual conditions inditions indicate a probable defective touch control Circuit or button P.C.B.
assembly
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.
8. Display does not show the time of day when clear button is touched.
9. Oven lamp and turn table motor do not stop although cooking is finished.
Check if the RELAY(RY4) contacts close and if they are close, replace touch control circuit.
CONDITION CHECK RESULT CAUSE REMEDY
Display does Normal Replace
Check each button for Malfunction of sub
not show continuity of the button pcb assembly control box
programming sub-assembly
at all, even if
keyboard is
touched.
(TROUBLE 7)
When ERROR 2 ERROR 3 come on display.
CONDITION CHECK RESULT CAUSE REMEDY
ERROR 2 & Check continuity of thermistor 0 or infinite Replace Replace
ERROR 3 (resistance of thermistor)
come on
display
Approx
200~300k
(room
temperature)
No Defective
Check continuity of heater Replace
continuty heater
(convection, upper, lower)
continuity Defective touch Replace
control circuit
24
9. MEASUREMENT AND TEST
1. MEASUREMENT OF THE MICROWAVE 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. A cylindrical container of borosilicate glass is used for the test. It has a maximum thickness of 3mm, an external
diameter of approximately 190mm and a height of approximately 90mm.
The mass of the container is determined.
2. At the start of the test, the oven and the empty container are at ambient temperature. Water having an initial
temperature of 10 C 1 C is used for the test. The water temperature is measured immediately before it is poured
into the container.
3. A quantity of 1000g 5g of water is added to the container and its actual mass obtained.
The container is then immediately placed in the centre
of the oven shelf, which is in its lowest normal position.
The oven is operated and the time for the water
temperature to attain 20 C 2 C is measured. The
oven is then switched off and the final water
temperature is measured within 60s.
NOTE 1 - The water stirred is before its temperature is
measured.
NOTE 2 - Stirring and measuring devices are to have a
low heat capacity.
4. The microwave power output is calculated from the
formula
P = 4,187 mW (T2 -T1) + 0.55 mC(T2 - T0)/t
where
P is the microwave power output, in watts ;
mW is the mass of the water, in grams ;
mc is the mass of the container, in grams ;
T0 is ambient temperature, in degrees Celsius ;
T1 is the initial temperature of the water, in degree Celsius ;
T2 is the final temperature of the water, in degrees Celsius ;
t is the heating time, in seconds, excluding the magnetron filament heating-up time.
The microwave power output is stated in watts, rounded off to the nearest 50W
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)
Heating time for power output: (T2 = T0)
A (second) 70 64 60 56 52 49 47 44 42 40 38
B (W) 600 650 700 750 800 850 900 950 1000 1050 1100
25
2. MICROWAVE RADIATION TEST
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.
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/Cm2.
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.
26
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 10%
Filament winding ... Approx. 0
Primary winding ... Approx. 1.2
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 10M once the capacitor charged.
3) A shorted capacitor will show continuous continuity.
4) An open capacitor will show constant 10M .
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 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 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.
27
4. COMPONENT ACTION
MAGNE- UPPER LOWER REAR CONVEC-
COOKING MODE
TRON ELEMENT ELEMENT ELEMENT TION FAN
M/W
GRILL-1
GRILL-2
GRILL-3
COMBI-1
COMBI-2
MANUAL COMBI-3
MODE COMBI-4
COMBI-5
CONVECTION100~130
CONVECTION140~150
CONVECTION160~250
ONE CAKE/BREAD
TOUCH CRUSTY
ROAST BEEF
ROAST CHICKEN
ROAST PORK
BAKED FISH
AUTO BAKED POTATO
MODE BAKED POTATO
ROAST POTATO
FRESH VEGETABLES
FROZEN VEGETABLES
CASSEROLE
28
PRIMARY INTERLOCK INTERLOCK HIGH VOLTAGE
SWITCH(UPPER) MONITOR SWITCH TRANSFORMER
RD COM. NO. WH RD
NC.
POWER SUPPLY : RD RD RD BK RD RD WH
SINGLE PHASE
ONLY LINE FILTER ASS Y THERMAL
CUT-OUT H.V.
L BR FUSE RD BK FUSE
FM OL CM BK TTM
L L H.V.
BL WH CAPACITOR
CONVECTION HEATER
TOP HEATER
MAGNETRON
N N N
BR YW
10. WIRING DIAGRAM
GE BK BL BK
GN
YW
H.V. DIODE
BL
WH RD YW
29
NC.
COM. NO. BL