Daewoo KOT-123Q0A User manual

Service Manual
Microwave Oven
Model : KOT-123Q0A
DAEWOO ELECTRONICS CO., LTD.
http : //svc.dwe.co.kr
S/M No. : T123Q0A001
✔ 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).

1
TABLE OF CONTENTS
SAFETY AND PRECAUTIONS............................................................................................ 2
FOR SAFE OPERATION .......................................................................................................................2
FOR SAFE SERVICE PROCEDURES. .....................................................................................................2
SPECIFICATIONS .......................................................................................................... 3
EXTERNAL VIEW ............................................................................................................ 4
OUTER DIMENSION ...........................................................................................................................4
FEATURE DIAGRAM ...........................................................................................................................5
CONTROL PANEL ..............................................................................................................................6
OPERATIONS AND FUNCTIONS ..................................................................................... 7
DISASSEMBLY AND ASSEMBLY ....................................................................................... 8
INTERLOCK MECHANISM AND ADJUSTMENT .................................................................. 19
TROUBLESHOOTING GUIDE ........................................................................................... 22
MEASUREMENT AND TEST .............................................................................................. 29
MEASUREMENT OF THE MICROWAVE POWER OUTPUT ........................................................................29
MICROWAVE RADIATION TEST ............................................................................................................30
COMPONENT TEST PROCEDURE ........................................................................................................31
WIRING DIAGRAM ........................................................................................................ 33
PRINTED CIRCUIT BOARD .............................................................................................. 34
CIRCUIT CHECK PROCEDURE ............................................................................................................34
P.C.B. CIRCUIT DIAGRAM ..................................................................................................................38
P.C.B.LOCATION NO ........................................................................................................................39
EXPLODED VIEW AND PARTS LIST ................................................................................... 40
DOOR ASSEMBLY ..............................................................................................................................40
CONTROL PANEL ASSEMBLY ..............................................................................................................40
TOTAL ASSEMBLY ...............................................................................................................................40
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 micro-
wave source and make repairs as necessary : (1) Interlock operation (2) proper door closing (3) seal and
sealing surfaces (arcing, wear and other damage) (4) damage to or loosening of hinges and latches (5) evi-
dence of dropping or abuse.
(c) Before turning on microwave power for any service test or inspection within the microwave generating
compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment, integ-
rity and connection.
(d) Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation and
transmission systems shall be repaired, replaced or adjusted by procedures described in this manual before
the oven is released to the owner.
(e) A microwave leakage check to verify compliance with the Federal Performance Standard should be
performed on each oven prior to release to the owner.

2
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.
(a) inform the manufacturer, importer or assembler,
(b) repair the unit at no cost to the owner,
(c) attempt to ascertain the cause of the excessive leakage,
(d) 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 and CDRH immediately.
This Device is to be Serviced Only by Properly Qualified Service Personnel. Consult the Service Manual for
Proper Service Procedures to Assure Continued Compliance with Federal Performance Standard for Microwave
Ovens and for Precautions to be Taken to Avoid Possible Exposure to Excessive Microwave Energy.
CAUTION
Microwave Radiation
Personnel Should Be Exposed to the Microwave Energy Which May Radiate from the Magnetron or Other Micro-
wave Generating device if it is Improperly Used or Connected. All Input and Output Microwave Connections,
Wave-Guide,Flanges and Gaskets Must be Secure. Never Operate the Device Without a Microwave Energy
Absorbing Load Attached. Never Look Into an Openwaveguide or Antenna While the Device is Energized.
CAUTION

3
SPECIFICATIONS
* SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE.
POWER SUPPLY 120V ~ 60 Hz, SINGLE PHASE WITH GROUNDING
POWER CONSUMPTION
MICROWAVE 1400W
GRILL
COMBINATION
MICROWAVE ENERGY OUTPUT 900W
MICROWAVE FREQUENCY 2450MHz
HOOD LIGHT 30 W
× 2
OUTSIDE DIMENSIONS (W × H × D) 564 × 407 × 423 mm (22.2 × 16.0 × 16.6 in.)
CAVITY DIMENSIONS (W × H × D) 374 × 233 × 372 mm (14.7 × 9.2 × 14.6 in.)
NET WEIGHT APPROX. 20 Kg (44.1lbs)
TIMER 59 min. 99 sec.
FUNCTION SELECTIONS MICROWAVE
POWER SELECTIONS 10 LEVELS
CAVITY VOLUME 1.2 Cu. Ft.

4
EXTERNAL VIEW
1. OUTER DIMENSION (KOT-123Q)

5
EXTERNAL VIEW
2. FEATURE DIAGRAM
1. DOOR SCREEN
Allows viewing of food. The screen is transparent to light, but prevents microwave escaping.
2. DOOR LATCH
When the door is closed it will automatically shut off. If the door is opened while the oven is operating, magnetron will
automatically shut off.
3. CONTROL PANEL
4. COOKTOP LIGHT
5. GREASE FILTER
6. DOOR RELEASE BUTTON
Pushing this button stops oven operation and opens the door.
7. CHARCOAL FILTER (optional, not shown)
7

6
EXTERNAL VIEW
3. CONTROL PANEL
8. TIME SET PAD
Used to set the cooking time and the present
time.
9. DISPLAY
Cooking time, power level, indicators and present
time are displayed.
10.QUICK START
Touch to set the desired reheat time by 30
seconds.
11. ONE TOUCH
Used to cook or reheat specific quantities of food.
12.MORE
Used to add time to one touch cooking.
13.LESS
Used to remove time from one touch cooking.
14.AUTO DEFROST
Used to defrost foods.
15.POWER
Used to set power level.
16.CLOCK / A.START (AUTO START)
Used to set clock and also used to set a delayed
auto start.
17.STOP/CLEAR
Used to stop the oven operation or to delete the
cooking data.
18.START
Used to start the oven.
19.FAN
Used to turn on the exhaust fan.
20.LIGHT
Used to turn on the cooktop light.
19
17
15
14
12
20
18
16
10
8
11
9
13
/
/

7
OPERATIONS AND FUNCTIONS
1. Connect the main lead to an electrical outlet.
2. After placing the food in a suitable container, open the oven door and put it on the glass tray. The glass tray must
always be in place during cooking.
3. Close the door securely.
4. When the oven door is opened, the light turns off.
5. The oven door can be opened at any time during operation by touching the door release button on the control panel.
The oven will automatically shut off. To restart the oven, close the door and then touch START.
6. Each time a pad is touched, a BEEP will sound to acknowledge the touch.
7. The oven automatically cook on full power unless set to a lower power level.
8. The display will show : 0 when the oven is plugged in.
9. Time clock returns to the present time when the cooking time ends.
10.When the STOP/CLEAR pad is touched during the oven operation, the oven stops cooking and all information
retained. To erase all information (except the present time), touch the STOP/CLEAR pad once more. If the oven door
is opened during the oven operation, all information is retained.
11.If the START pad is touched and the oven does not operate, check the area between the door and door is closed
securely. The oven will not start cooking under the door is completely closed or the program has been reset.
Wattage output chart
The power level is set by pressing the Power pad. The chart shows the display, the power level and the percentage of
power.
Touch Power pad,
Once the Touch Power Level (Display) Approximate Percentage of Power
POWER P-HI 100%
9P-90 90%
8P-80 80%
7P-70 70%
6P-60 60%
5P-50 50%
4P-40 40%
3P-30 30%
2P-20 20%
1P-10 10%
0P- 0 0%
Make sure the oven is properly installed and plugged into the electrical outlet.
NOTE

8
DISASSEMBLY AND ASSEMBLY
Cautions to be observed when troubleshooting
Unlike many other appliances, the microwave oven is high-voltage, high-current equipment. It is completely safety during
normaloperation. However, carelessness in servicingthe oven can result inan electrical shock or possibledanger 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
microwaveovenisdesignedtobeusedwithgrounding.
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
stopped, electric charge remains in the high voltage
capacitor. When replacing or checking parts, short
betweenovenchassisandthenegativehighterminalof
the high voltage capacitor, by using a properly insu-
lated screwdriver to discharge.
4. Whenthe 20A fuse is blown out due to the operation ofthe
monitorswitch;replaceprimary interlockswitch,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 connec-
tions are tightened.
6. Do not operate without cabinet.
Service personnel should remove their watches whenever working close to ot repairing the magnetron.
CAUTION
When servicing the appliance, need a care of touching or replacing high potential parts because of electrical
shock or exposing microwave. These parts are as follows - HV Transformer, Magneton, HV Capacitor, HV Diode.
WARNING

9
DISASSEMBLY AND ASSEMBLY
1. TO REMOVE CABINET AND AIR GRILLE
1) Removethetenscrewsfromthe top, sideandrearofthe
cabinet.
2) Push the cabinet backward.
3) Removetwolongscrewsfromthe front ofthemicrowave
oven that secure the air grill to the oven and pull the top
of the air grill out so that the tabs are free of their slots
andremoveit.Liftthebottom of theairgrilltounhookthe
locking tabs from their slots and remove it.
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 reassembly.
After replacing the door assembly, perform a check of correct alignment with the hinge and cavity front plate.
NOTE

10
3. TO REMOVE DOOR PARTS
1) Remove the gasket door from door plate.
2) Remove the barrier screen inner from door plate.
3) Remove the door frame from door plate.
4) Remove the stopper hinge top from door plate.
5) Remove the spring and the hook.
6) Remove the barrier screen outer from door frame.
7) Reverse the above steps for reassembly.
PART CODE PART NAME DESCRIPTION QTY
A01 3512300700 GASKET DOOR PP 1
A02 3517004200 BARRIER-SCREEN *I POLYESTER T0.1 1
A03 3513100900 HOOK POM 1
A04 3511708100 DOOR PAINTING AS KOR-121MOA 1
A05 3517005500 BARRIER-SCREEN *O PC 1
A06 3512204200 FRAME DOOR PC 1
A07 3515202900 STOPPER HINGE *T AS KOR-121MOA 1
DISASSEMBLY AND ASSEMBLY
A07
✔ Caution: In this Service 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
DISASSEMBLY AND ASSEMBLY
4. METHOD TO REDUCE THE GAP BETWEEN THE DOOR SEAL AND THE OVEN FRONT SURFACE
1) To reduce gap located on part ‘A’.
•Loosentwoscrewsonstopper hingetop,andthenpush
the door to contact the door seal to oven front surface.
• Tighten two screws.
2) To reduce gap located on part ‘B’.
• Loosen three screws on stopper hinge top, and then
push the door to contact the door seal to oven front
surface.
• Tighten three screws.
3) To reduce gap located on part ‘C’.
• Loosen a screw on interlock switch assembly located
top of oven body.
•Draw the interlock switch assembly inward as possi-
ble to engage with hook on the door bottom.
• Tighten a screw.
4) To reduce gap located on part ‘D’.
• Loosen a screw on interlock switch assembly located bottom of oven body. And (4) are same as step (3).
A small gap may be acceptable if the microwave leakage does not exceed 4mW/cm
2
.
NOTE

12
DISASSEMBLY AND ASSEMBLY
5. TO REMOVE CONTROL PANEL PARTS
REF.NO PART CODE PART NAME DESCRIPTION QTY REMARK
B01 3518521900 MEMBRANE KOT-123Q 1
B02 3516722200 CONTROL PANEL PC 1
B03 3516802000 BACK PLATE SECC, t 0.5 1
B04 3514321600 PCB AS KOT-123Q 1
B05 7S341W40B1 SCREW SPECIAL T2S PAN 4X12PW SE MFZN 4
B06 3513702500 LEVER DOOR OPEN POM 1
B07 441B655072 SPRING BUTTON HSWR 1
B08 3516907800 BUTTON DOOR OPEN PC 1
B09 3515501600 WINDOW DISPLAY PC 1
✔ Caution: In this Service 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)

13
DISASSEMBLY AND ASSEMBLY
1) Remove four screws which secure the control panel,
push up snap fits and draw forward the control panel
assembly.
2) Disconnect all the lead wires connected to control panel
assembly.
3) Remove the door open lever from the control panel.
4) Remove four screws which secure the PCB assembly to
control panel.
5) Disconnect membrane tail from the connector of the
PCB assembly.
6) Detach membrane from the control panel.
7) Remove door open button and button spring from the
control panel.
8) Reverse the above steps for reassembly.
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 capacitor holder with the capacitor.
3) Reverse the above steps for reassembly.
High voltage circuit wiring

14
DISASSEMBLY AND ASSEMBLY
7. TO REMOVE MAGNETRON
1) Remove a screw which secure the magnetron.
2) Remove the magnetron from the wave guide.
3) Reverse the above steps for reassembly.
Never install the magnetron without the metallic gasket plate which is packed with each magnetron to prevent
microwaveleakage.Wheneverrepairwork iscarriedoutonmagnetron,checkthe microwave leakage.Itshallnot
exceed 4mW/cm
2
for a fully assembled oven with door normally closed.
NOTE

15
DISASSEMBLY AND ASSEMBLY
8. TO REMOVE WIND GUIDE ASSEMBLY
1) Remove a screw which secure the wind guide assembly.
2) Draw forward the wind guide assembly.
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.
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
DISASSEMBLY AND ASSEMBLY
10.TO REMOVETHE VENTILATION(VENT) MOTOR
1) Remove the cover *B.
2) Remove six screws for the air guide *B.
3) Remove the air guide *B.
4) Remove two screws for the vent motor and lift the vent
motor.
5) Reverse the above steps for reassembly.
11. TO REMOVE THE CAVITY THERMAL CUTOUT
1) Remove the air grill and cabinet from the microwave
oven.
2) Remove four screws for the supporters and air guide top.
3) Remove the supporters and lift the air guide top.
4) Remove a screw for the cavity thermal cutout.
12. TO REMOVE THE THERMOSTAT (BOTTOM/
HOOD)
1) Remove the air grill from the microwave oven.
2) Remove the screw from the top center tab of the control
panel.
3) Removethe mounting screw from the bottom thermostat
and lift the bottom flange out at slot in the chassis.
* Hood thermostat is same as bottom thermostat
method.
Ventilation motor
air guide *B
cover *B
56 40

17
DISASSEMBLY AND ASSEMBLY
13. TO REMOVE THE CAVITY LAMP
1) Remove the screws for the air grille and remove the air
grille.
2) Push the tab on cavity lamp bracket and lift the cavity
lamp bracket.
3) Remove the screw from the cavity lamp bracket.
14. TO REMOVE THE TRAY MOTOR
1) Remove three screws from the base plate and remove it.
2) Pull the connectors off the tray motor terminal.
3) Remove two screws from the tray motor and remove the
motor.
15. TO REMOVE THE HOOD LAMP SOCKET
1) Remove three screws from the base plate and remove it.
2) Remove the screw for the heat protector and remove it.
3) Pull the connectors off the hood lamp socket terminals.
4) Removethe screw for thehood lamp socket andremove
it.

18
DISASSEMBLY AND ASSEMBLY
16. TO REMOVE THE LINE FUSE
1) Remove two screws from the air grill and remove the
grill.
2) Remove the screw from the top center tab of the control
panel.
3) Without touching the metal ends, remove the defective
line fuse from its holder.
17. TO REMOVE THE HOOD LAMP
1) Remove a screw from the cover lamp of the base plate.
2) Pull down the cover lamp.
3) Remove the hood lamp from the hood lamp socket.

19
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 micro-
wave.
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 micro switch. Then the button of the primary interlock switch bring it
under “ON” condition.
Adjustement1
When the door is closed, the switch button is pushed by
the hook. The movement of the switch button should
exceed 1.2mm measured at the top of the bottom.