Daewoo KQG-1N1AS User manual

Service Manual
Model:KQG-1N1AS
Microwave Oven & Grill
Oct. 2009
S/M No. : G867T9A001

1
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.
(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.
TABLE OF CONTENTS
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO
EXCESSIVE MICROWAE ENERGY................................................................................................................................1
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
INSTALLATION ................................................................................................................................................................7
OPERATIONS AND FUNCTIONS ...................................................................................................................................8
DISASSEMBLY AND ASSMBLY.....................................................................................................................................9
INTERLOCK MECHANISM AND ADJUSTMENT.........................................................................................................18
TROUBLESHOOTING GUIDE.......................................................................................................................................19
MESUREMENT AND TEST............................................................................................................................................23
MEASUREMENT OF THE MICROWAVE POWER OUTPUT ...................................................................................23
MICROWAVE RADIATION TEST ...............................................................................................................................24
COMPONENT TEST PROCEDURE...........................................................................................................................25
WIRING DIAGRAM.........................................................................................................................................................26
PRINTED CIRCUIT BOARD...........................................................................................................................................27
CIRCUIT CHECK PROCEDURE.................................................................................................................................27
PCB CIRCUIT DIAGRAM............................................................................................................................................30
P.C.B. LOCATION NO.................................................................................................................................................31
EXPLODED VIEW AND PARTS LIST...........................................................................................................................32
DOOR ASSEMBLY......................................................................................................................................................32
CONTROL PANEL ASSEMBLY..................................................................................................................................32
TOTAL ASSEMBLY.....................................................................................................................................................32

2
SAFETY AND PRECAUTIONS
CAUTION : This Device is to be Serviced Only by Properly Qualified Service Personnel. Consult the Service
Manual for Proper Service Procedures to Assure Continued Safety Operation and for Precautions
to be Taken to Avoid Possible Exposure to Excessive Microwave Energy.
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.
CAUTION
MICROWAVE RADIATION
PERSONNEL SHOULD NOT BE EXPOSED TO THE MICROWAVE ENERGY WHICH MAY RADIATE FROM
THE MAGNETRON OR OTHER MICROWAVE GENERATING DEVICE IF IT IS IMPROPERLY USED OR
CONNECTED. ALL INPUT AND OUTPUT MICROWAVE CONNECTIONS. WAVEGUIDES FLANGES AND
GASKETS MUST BE SECURED. NEVER OPERATE THE DEVICE WITHOUT A MICROWAVE ENERGY
ABSORBING LOAD ATTACHED. NEVER LOOK INTO AN OPEN WAVEGUIDE OR ANTENNA WHILE THE
DEVICE IS ENERGIZED.

3
SPECIFICATIONS
MODEL KQG-1N1A9A52
POWER SUPPLY 120V~60HZ, SINGLE PHASE WITH EARTHING
POWER MICROWAVE 1500 W
CONSUMPTION GRILL 1050 W
MICROWAVE ENERGY OUTPUT 1000 W
MICROWAVE FREQUENCY 2450MHz
OUTSIDE DIMENSIONS (W X H X D) 515 x 304 x 375 mm (20.3 x 12.0 x 14.8 in.)
CAVITY DIMENSIONS (W X H X D) 356 x 239 x 358 mm(14.0 x 9.4 x 14.1 in.)
NET WEIGHT APPROX. 13.2 kg (29.1lbs)
TIMER 59min. 99sec.
FUNCTION SELECTIONS MICROWAVE, GRILL
POWER SELECTIONS 10 LEVELS
CAVITY VOLUME 1.1 Cu.Ft
* Specifications are subject to change without notice.
EXTERNAL VIEW
1. OUTER DIMENSION
20.3 14.8
12.0

5
12 3 45
6
7
890q
w
e
1Door latch - When the door is closed, it will
automatically shut off. If the door is opened while
the oven is operating, the magnetron will
automatically shut off.
2Door seal - The door seal surfaces prevent
microwaves escaping from the oven cavity.
3Oven cavity
4Oven lamp - Automatically turns on during oven
operating.
5Safety interlock system
6Control panel
7Door open button - To open the door push the
door open button.
8Waveguide cover - Protects the microwave outlet
from splashes of cooking foods.
9Roller guide - This must always be used for
cooking together with the glass cooking tray.
0Coupler - This fits over the shaft in the center of
the oven cavity floor. This is to remain in the oven
for all cooking.
qGlass cooking tray - Made of special heat
resistant glass. The tray must always be in proper
position before operating. Do not cook food directly
on the tray.
wViewing screen - Allows viewing of food. The
screen is designed so that light can pass through,
but not the microwave.
eMetal Rack
2. FEATURES DIAGRAM

6
M/W Def . Grill Timer/g
Meat Poultry
1. Bread
2. Soup
3. Baked potato
4. Fresh Vegetable
5. Frozen vegetable
Stop
Clear Start speedy start
Kitchen
Timer
Clock
Beverage
Frozen
Pizza
Auto
Cook
AUTO COOK
AUTO DEFROST
Popcorn
Dinner
Plate
Grill
Power
Fish
Defrost
r
t
j
h
d
u
y
o
a
p
o
s
f
i
g
rDisplay-Cooking time, power level, indicators and
present time are displayed.
tAuto Cook-Used to cook or reheat.
yGrill-Used to cook GRILL.
uPOWER-Used to set power level.
iDefrost-Used to defrost foods.(for time)
oOne touch-Used to cook or reheat specific
quantities of food.
pLess-Used to remove time from cooking.
aMore-Used to add time to cooking.
sAuto Defrost-Used to defrost foods.
(for weight)
dTime set pad-Used to set the cooking time
and the present time.
fKitchen Timer-Used as a minute timer, to delay
the start of cooking, or to set a holding time after
cooking.
gClock-Used to set clock.
hStop/Clear-Used to stop the oven operation or to
delete the cooking data.
jStart/speedy start-Used to start the oven
and also used to set a reheat time.
3. CONTROL PANEL

7
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 oven 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.
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 13 amperes, 120 Volts, 60 Hz grounded outlet.
Power supply cord is about 0.8 meters long.
1) A short power-supply cord is provided to reduce the risks resulting from becoming entangled in or tripping over a
longer cord.
2) Longer cord sets or extension cords are available and may be used if care is exercised in their use.
3) If a long cord or extension cord is used:
1 The marked electrical rating of the cord set or extension cord should be at least as great as the electrical rating of
the appliance.
2 The extension cord must be a grounding type 3-wire cord.
3 The longer cord should be arranged so that it will not drape over the counter top or tabletop where it can be pulled
on by children or tripped over unintentionally.
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.

8
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 on.
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 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.
12. When using the GRILL mode ;
• Do not open the door so often, the temperature inside the oven decrease and the cooking may not be completed
in setting time.
• Never touch the oven window and metal interior of the oven when taking food in and out, because the
temperature inside the oven and door is very high.
• When using these modes, be careful as the tray will be hot to touch, use oven gloves or pot holders while
handing tray.
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.
Make sure the oven is properly installed and plugged into the electrical outlet.
Touch POWER pad. Power level(Display) Approximate Percentage of Power
Once P-HI 100%
Twice P-90 90%
3 times P-80 80%
4 times P-70 70%
5 times P-60 60%
6 times P-50 50%
7 times P-40 40%
8 times P-30 30%
9 times P-20 20%
10 times P-10 10%
11 times P-00 0%

9
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 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, HV Fuse.
DISASSEMBLY AND ASSEMBLY

10
1. To remove cabinet
1) Remove three 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 reassembly.
NOTE : After replacing the door assembly, perform a check of correct alignment with the hinge and cavity front plate.

11
3. To remove door parts.
(1) Remove the gasket door from the door painting as.
(2) Remove the barrier screen*i from the door painting as.
(3) Remove the door sub as from the door painting as.
(4) Remove the stopper hinge top from the door painting as.
(5) Remove the spring and the hook.
(6) Remove the barrier screen*o from the door sub as.
(7) Reverse the above steps for reassembly.
A01 3517010820 BARRIER-SCREEN*O TEMP GLASS T3.2 MIRROR 1
A02 3512210550 FRAME DOOR KOR-1N1A SILVER SPRAY 1
A03 3515204120 STOPPER HINGE*T AS KOR-6L0B1A 1
A04 3511727500 DOOR PAINTING AS KOR-1N0A9A 1
A05 3517006000 BARRIER-SCREEN*I PE T1.0 1
A06 3512301330 GASKET DOOR PP 1
A07 3513100700 HOOK POM 1
A08 3515101900 SPRING HOOK PW-1 1
REF. NO PART CODE PART NAME DESCRIPTION Q'TY REMARK
DOOR ASSEMBLY : 3511727430

12
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 the stopper hinge top, and then
push the door to contact the door seal to the oven front
surface.
• Tighten two screws.
(2) To reduce gap located on part ‘B’
• Loosen two screws on the stopper hinge under, and
then push the door to contact the door seal to the oven
front surface.
• Tighten two screws.
(3) To reduce gap located on part ‘C’
• Loosen the screw on the interlock switch assembly
located the top of the oven body.
• Draw the interlock switch assembly inward as possible
to engage with the hook on the door bottom.
• Tighten a screw.
(4) To reduce gap located on part ‘D’
• Loosen the screw on the interlock switch assembly
located the bottom of the oven body.
NOTE : A small gap may be acceptable if the microwave leakage does not exceed 4mW/cm2.
AC
BD

13
5. To remove control panel parts.
B01
B02
B03
B04
B05
B06
B07
(1) Remove the screw which secure the CONTROL-PANEL, push up two snap fits and draw forward the control panel
assembly.
(2) Remove three screws which secure the PCB assembly to the CONTROL-PANEL.
(3) Disconnect membrane tail from the connector of the PCB assembly.
(4) Remove the PCB from the CONTROL-PANEL.
(5) Remove the membrane, holder LED, lever door open, spring button and button door open from the CONTROL-PANEL.
(6) Reverse the above steps for reassembly.
B01 3518573450 SWITCH MEMBRANE KQG-1N1A9A52 1
B02 3516737810 CONTROL-PANEL KOR-1N1H SPRAY 1
B03 PKMPMSZZ40 PCB MAIN MANUAL AS KQG-1N4A9A27 1
B04 7122401211 SCREW TAPPING T2S TRS 4X12 MFZN 3
B05 3513702710 LEVER DOOR OPEN PP 1
B06 441G430171 SPRING BUTTON SWP DIA. 0.7 1
B07 3516915840 BUTTON DOOR OPEN ABS SG-0760D, SG-175 1
REF. NO PART CODE PART NAME DESCRIPTION Q'TY REMARK
C/PANEL ASSEMBLY : PKCPSWZZ50

14
6. To remove high voltage capacitor.
1) Remove the 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 the screw which secure the magnetron.
2) Remove the magnetron.
3) Reverse the above steps for reassembly.
NOTE : 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
gasket
plate
Magnetron
antenna
Cooling fin Filament
terminal
<MAGNETRON>
Wave guide Magnetron antenna
Metallic gasket plate

15
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.
8. To remove wind guide assembly.
1) Remove the 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.

16
10. To remove tray motor.
1) Remove the coupler in the cavity.
2) Turn the set upside down.
3) Cut the tray motor cover part from the base plate.
4) Remove the tray motor cover.
5) Remove a screw which secure the tray motor.
6) Remove the tray motor.
7) Reverse the above steps for reassembly except for
securing the tray motor cover with screw.
11. To remove heater assembly.
1) Remove one side of the heater harness.
2) Remove a screw which secure the cover insulator top.
3) Remove the cover insulator top.
4) Remove the heater top assembly.
5) Reverse the above steps for reassembly.

17
12. To remove heater parts
C01 C02 C03 C04 C05
C01 3512765100 HARNESS HEATER KOC-970T1S TEFLON 1
C02 7S312X40A1 SCREW TAPPING T1 TRS 4X10 SE MFZN 2
C03 3510607800 BRACKET HEATER *T SBHG T0.5 2
C04 3512808320 HEATER MIRACLON 60V AC, 500W, 240MM 2
C05 3511408100 COVER HEATER *T STS430 T0.5 1
REF. NO PART CODE PART NAME DESCRIPTION Q'TY REMARK
HEATER TOP ASSEMBLY : 3512807640

18
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 NO position (NO position).
(2) DOM switch and interlock monitor switch
When the door is closed, the hook pushes the lock lever downward. The hook presses the button of the interlock monitor
switch to bring it under “OFF” condition (NO position) and the lock lever presses the button of the DOM switch to bring it
under “ON” condition (NO position).
(3) Adjustment steps
a) Loosen the mounting screw.
b) Adjust interlock switch assembly position.
Actuation distance of primary and secondary interlock switch shall be adjusted almost 0.7mm.
c) Make sure that lock lever moves smoothly after adjustment is completed.
d) Tighten completely a mounting screw.
ADJUSTMENT :
Interlock monitor switch
When the door is closed, the interlock monitor switch should be opened (NO position) before other switches are closed.
When the door is opened, the interlock monitor switch should be closed (NC position) after other switches are opened.
NOTE :
Microwave emission test should be performed after adjusting interlock mechanism. If the microwave emission exceed
4mW/cm2, readjust interlock mechanism.

19
(TROUBLE 1) Oven does not operate at all ; any inputs can not be accepted.
TROUBLESHOOTING GUIDE
CONDITION CHECK
Check continuity of interlock
monitor switch with door closed
Check continuity of primary
inter-lock switch contact with
door partially open until
interlock mon-itor switch
contact close (COM ↔NC)
Malfunction of
interlock moni-
tor switch
Shorted con-
tacts of primary
interlock switch.
RESULT
Continuity
No Continuity
No Continuity
CAUSE REMEDY
Replace
Fuse blows.
Replace
Defective low
voltage
transformer
0Ωor infinite
Approx.
220~320 Ω
(normal)
Replace
Check continuity of primary
winding of low voltage
transformer
Defective high
voltage capacitor
Normal Replace
Disconnect one side of the lead
wire connected of from high
voltage transformer to the high
voltage capacitor and operate
the unit
Continuity
Defective high
voltage
transformer
Fuse again
blows
Replace
Check continuity of both primary
and secondary interlock switch
with door colosed
Malfunction of
interlock switch
Continuity
ReplaceNo Continuity
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 transformer, disconnect one lead 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 connected of the terminals and power cord before check the parts listed
below.

20
CONDITION CHECK
Display do not shown
countdown Malfunction of
D.O.M switch
RESULT CAUSE REMEDY
Replace
Outlet has
proper
voltage Fuse
does not
blow.
Check continuity of
noise filter board Defective
magnetron
No
Continuity Replace
Check continuity of
power supply cord Open power
supply cord
No
Continuity Replace
Defective touch
control circuit
Normal Replace
CONDITION CHECK
Check continuity of primary
interlock switch Malfunction of
primary interlock
switch
RESULT
No
Continuity
CAUSE REMEDY
Adjust or
replace
Turn table
motor and
oven lamp
do not turn
on Check continuity of secondary
interlock switch Malfunction of
secondary
interlock switch
No
Continuity Adjust or
replace
Check D.C. voltage being
supplied to RELAY (RY2) coil Defective touch control circuit
0 V Replace
Faulty contacts of
RELAY (RY2) or
open relay coil
Approx.
12 VDC Replace
NOTE
All these switches must be replaced at the same time, please refer to “Interlock Mechanism And Adjustment”.
(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.