Daewoo KOG-37050P User manual

S/M No. : G37050P001
Service Manual
Microwave Oven
OCT. 1999
DAEWOO ELECTRONICS CO., LTD
http : //svc.dwe.co.kr
Model :
KOG-37050P
KOG-39050P
✔ 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
SPECIFICATIONS ............................................................................................................................ 3
EXTERNAL VIEW ............................................................................................................................ 4
1. OUTER DIMENSION .................................................................................................................... 4
2. FEATURE DIAGRAM ................................................................................................................... 5
INSTALLATION ................................................................................................................................ 6
OPERATIONS AND FUNCTIONS ................................................................................................... 7
DISASSEMBLY AND ASSEMBLY .................................................................................................. 8
INTERLOCK MECHANISM AND ADJUSTMENT ........................................................................... 17
TROUBLE SHOOTING GUIDE ........................................................................................................ 18
MEASUREMENT AND TEST ........................................................................................................... 20
1. MEASUREMENT OF THE MICROWAVE POWER OUTPUT ..................................................... 20
2. MICROWAVE RADIATION TEST ................................................................................................ 21
3. COMPONENT TEST PROCEDURE ............................................................................................ 22
WIRING DIAGRAM .......................................................................................................................... 23
EXPLODED VIEW AND PARTS LIST ............................................................................................. 24
1. DOOR ASSEMBLY ...................................................................................................................... 24
2. CONTROL PANEL ASSEMBLY ................................................................................................... 24
3. TOTAL ASSEMBLY ...................................................................................................................... 24
PRECAUTIONSTOBEOBSERVEDBEFOREANDDURINGSERVICINGTO
AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY
(a) Do not operate or allow the oven to be operated with the door open.
(b)Makethefollowingsafetychecksonallovenstobeservicedbeforeactivatingthemagnetronorothermicrowave
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
transmissionsystems shall be repaired,replaced, or adjusted byprocedures described in thismanual before the
oven is released to the owner.
(e)AmicrowaveleakagechecktoverifycompliancewiththeFederalperformancestandardshouldbeperformedon
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 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 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.
IMPORTANT
This oven is designed for counter-top use only.
NOTE

3
SPECIFICATIONS
SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE.
MODEL KOG-3705 KOG-3905
POWERSUPPLY 220V~60Hz, SINGLE PHASE WITH EARTHING
POWERCONSUMPTION MICROWAVE 1200W 1300W
GRILL 1050W 1050W
COMBINATION 2200W 2350W
MICROWAVE ENERGY OUTPUT 800W 900W
MICROWAVE FREQUENCY 2450MHz 2450MHz
OUTSIDE DIMENSIONS (W X H X D) 465 x 279 x 360 mm 495 x 294 x 388 mm
CAVITY DIMENSIONS (W X H X D) 290 x 220 x 306 mm 320 x 244 x 338 mm
NET WEIGHT APPROX. 13.4 Kg APPROX. 15.5 Kg
TIMER 35 min. DUAL SPEED
FUNCTION SELECTIONS MICROWAVE/GRILL/COMBINATION
POWERSELECTIONS 5 LEVELS
CAVITY VOLUME 0.7 Cu.Ft. 0.9 Cu.Ft.

4
EXTERNAL VIEW
1. OUTER DIMENSION
465(495)
279(294)
360(388)
Fig2. Side viewFig1. Front view

5
EXTERNAL VIEW
2. FEATURE DIAGRAM
1) Door seal - Door seal maintains the microwave energy within the oven cavity and prevents microwave leakage.
2) Reflector (Insulator Heater)
3) Heating Element
4) Oven cavity
5) Safety interlock system
6) Knob V.P.C - Used to select a microwave power level.
7) Knob timer - Used in setting cooking time for all functions.
8) Door release button - By pushing this button the latch system cut off all circuits and stops the oven before the door is opened.
9) Metal Rack
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) Roller guide - This must always be used for cooking together with the glass cooking tray.
12) Glass cooking tray - Made of special heat resistant glass.
Food in a proper receptacle is placed on this tray for cooking.
13) Door viewing screen - Allows viewing of food.
The screen is designed so that light can pass through, but not the microwave.
14) Door hook - 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.

6
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 11amperes, 220 Volts, 60 Hz.
Power supply cord is about 0.8 meters long.
• The voltage used must be the same as specified on this oven. Using a higher voltage may result in a fire or other
accident causing oven damage. Using low voltage will cause slow cooking. We are not responsible for damage
resulting from use of this oven with a voltage of ampere fuse other than those specified.
• This appliance is supplied with cable of special type, which, if damaged, must be repaired with cable of same type.
Such a cable can be purchased from DAEWOO and must be installed by a Qualified Person.
6. Examine the oven after unpacking for any damage such as:
A misaligned door, broken door or a dent in cavity.
If any of the above are visible, DO NOT INSTALL, and notify dealer immediately.
7. Do not operate the oven if it is colder than room temperature.
(This may occur during delivery in cold weather.) Allow the oven to become room temperature before operating.
This appliance must be earthed. In the event of an electrical short circuit, earthing reduces the risk of the electric shock by pro-
vidingan escape wireforthe electric current.This appliance is equippedwith a cordhavinga earthing wirewith a earthing plug.
The plug must be plugged into an outlet that is properly installed and earthed.
Improper use of the earthing plug can result in a risk of electric 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 of the extension cord should be equal
to or greater than the electrical rating of the appliance, or Do not use an extension cord.
WARNING
EARTHING INSTRUCTIONS

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. Choose cooking power level by setting V.P.C knob to
the desired position.
Refer to cookbook for recommended power levels.
5. Determine cooking time. Consult cookbook for recipe timing.
Oven light turns on and cooling fan starts to operate.
Microwave cooking starts.
6. You may open the door while the oven is operating.
As soon as the door is opened, the safety mechanisms stop the
generation of microwave power and the operation of cooking timer.
If you wish to change the time during cooking,
simply adjust the timer to the desired time.
7. When the timer reaches zero, a bell will ring and the unit will turn off.
Oven light turns off. If additional cooking time is needed and
the door is closed, the oven will automatically start when the timer is reset.
• To set MICROWAVE cooking
Set the variable power selector to the desired power level.
• To set GRILL cooking
Set the POWER SELECTOR to the(grill) position.
• To set COMBI cooking
Set the POWER SELECTOR to the (combi) position.
SYMBOL POWER LEVEL Approximate Percentage of Power
DEFROST 33 %
MED-HIGH 77 %
HIGH 100 %
When using the GRILL or COMBI mode;
• Donotopenthedoor so often,thetemperature inside theovendecrease and thecookingmay not becompletedin 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 handling tray.
NOTE
1.Whensettingtimer for less than 2 minutes,turnthe
timer past 2 minutes and then return to the correct
timer setting.
2.Variousclickingnoisesmaybeheardwhenturning
V.P.C knob. This is normal and does not affect the
operation of your microwave oven.
NOTE

8
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 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 observe the following precautions carefully.
1. Always remove the power plug 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, electric
charge remains in the high voltage capacitor.
When replacing or checking parts, short between oven chassis and
the negative high terminal of the high voltage capacitor,
by using a properly insulated screwdriver to discharge.
4. When the 15A fuse is blown out due to the operation of the monitor
switch; replace primary interlock switch, secondary interlock
switch and interlock monitor switch.
5. After repair or replacement of parts, make sure that the screws are
properly tightened, and all electrical connections are tightened.
6. Do not operate without cabinet.
Service personnel should remove their watches whenever working close to or replacing 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, Magnetron, HV Capacitor, HV Diode.
WARNING

9
DISASSEMBLY AND ASSEMBLY
1. To remove cabinet
(1) Remove three screws on cabinet back.
(2) Push the cabinet backward.
2. To remove door assembly
(1) Remove a screw which secure the stopper hinge top.
(2) Remove the door assembly from top plate of cavity.
(3) Reverse the above steps for reassembly.
After replacing the door assembly, perform a check of correct alignment with the hinge and cavity front plate.
CAUTION

10
DISASSEMBLY AND ASSEMBLY
3. To remove door parts.
KOG-3705
KOG-3905
(1) Remove the gasket door from door weld as.
(2) Remove the barrier screen inner from door weld as.
(3) Remove the door frame from door weld as.
(4) Remove the stopper hinge top from door weld as.
(5) Remove the spring and the hook.
(6) Remove the supporter barrier screen outer from door frame.
(7) Remove the barrier screen outer from door frame.
(8) Reverse the above steps for reassembly.
REF. NO PART CODE PART NAME DESCRIPTION QTY REMARK
A01 3512203810 FRAMEDOOR ABS XR-401 H-2938 1
A02 3517003050 BARRIER-SCREEN*O ACRYLT1.5 1
A03 3515304610 SUPPORTERBARR-S*O PP 1
A04 3515204100 STOPPER HINGE *T AS KOR-63150S 1
A05 3511705500 DOORWELD AS KOR-61150S 1
A06 3517002800 BARRIER-SCREEN *I POLYESTERT0.1 1
A07 3512300200 GASKETDOOR PP 1
A08 3513100700 HOOK POM 1
A09 3515101300 SPRINGHOOK PW1 1
REF. NO PART CODE PART NAME DESCRIPTION QTY REMARK
A01 3512204110 FRAMEDOOR ABS XR-401 H-2938 1
A02 3517003150 BARRIER-SCREEN*O ACRYLT1.5 1
A03 3515304410 SUPPORTER BARR-S*O PP 1
A04 3515204100 STOPPERHINGE *T AS KOR-63150S 1
A05 3511705620 DOOR WELD AS KOR-81250S 1
A06 3517002900 BARRIER-SCREEN*I POLYESTER T0.1 1
A07 3512300400 GASKETDOOR PP 1
A08 3513100700 HOOK POM 1
A09 3515101300 SPRING HOOK PW1 1
DOOR Assembly: 3711710320(KOG-3705)
3511710720(KOG-3905)
✔ 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’.
Loosen a screw on stopper hinge top, and then push the door to
contact the door seal to oven front surface.
Tighten a screw.
(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.
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.
(1) Remove the screw which secure the control panel, push up two snap fits and draw forward the control panel assembly.
(2) Remove the door open lever from the control panel.
(3) Remove two screws which secure the timer assembly.
(4) Remove the timer assembly.
(5) Pull out the timer knob from the timer.
(6) Pull out the timer coupler from the timer.
(7) Remove the screw which secure the V.P.C coupler.
(8) Pull out the V.P.C coupler, V.P.C knob and flat spring from the control panel.
(9) Remove the door open button and button spring from the control panel.
(10) Reverse the above steps for reassembly.
REF. NO PART CODE PART NAME DESCRIPTION QTY REMARK
B01 3513405510 KNOB VPC ABS XR-401 H-2938 1
B02 3516719010 CONTROL-PANEL ABS XR-401 H-2938 1KOG-3705
3516719310 KOG-3905
B03 4415A66910 SW MICRO VP-531A-OF/SZM-V16-FA-61 1
B04 3515101600 SPRING FLAT SUS 301 T0.5 1
B05 3517400500 COUPLER VPC KNOB POM 1
B06 7122401211 SCREW TAPPING T2S TRS 4x12 MFZN 1
B07 3517400400 COUPLER TIMER POM 1
B08 7122401211 SCREW TAPPING T2S TRS 4x12 MFZN 2
B09 3518204500 TIMER KN35MKD 09K-P 1
B10 3513405410 KNOB ABS XR-401 H-2938 1
B11 4415A17352 SW MICRO VP-533A-OF SPNO #187 200G 1
B12 3513702710 LEVER DOOR OPEN ABS XR-401 H-2938 1
B13 441G430171 SPRING BUTTON SWP DIA 0.7 1
B14 3516906910 BUTTON DOOR OPEN ABS XR-401 H-2938 1
CONTROL-PANEL AS: 3516720310(KOG-3705)
3516722900(KOG-3905)
✔ 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
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 wirng
7. To remove magnetron.
(1) Remove a screw 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 micro-
wave 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

14
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.

15
DISASSEMBLY AND ASSEMBLY
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 the three nuts.
(2) Remove the insulator heater assembly.
(3) Reverse the above steps for reassembly.

16
DISASSEMBLY AND ASSEMBLY
12. To remove heater parts.
REF.NO PART CODE PART NAME DESCRIPTION QTY REMARK
C01 7392500008 NUT HEX 6N-2-5SUS 1
C02 3515000600 SPACER INSULATOR *I C3771BD 2
C03 3513301100 INSULATOR HEATER SPP T0.8 1
C04 3512803500 HEATER 220V 1000W 1SOPE47503 1
C05 7002500613 SCREW MACHINE TRS 5X6 MFCR 1
C06 7002400413 SCREW MACHINE TRS 4X4 MFCR 2
INSULATOR HEATER AS: 3513302710
✔ 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)

17
INTERLOCK MECHANISM AND ADJUSTMENT
The door lock mechanism is a device which has been specially designed to completely eliminate microwave radiation when the
door is opened during operation, and thus to perfectly prevent the danger resulting from the leakage of microwave.
1. Primary interlock switch
When the door is closed, the hook locks
the oven door. If the door is not closed properly,
the oven will not operate. When the door is closed,
the hook pushes the button of the microswitch.
Then the button of the primary interlock switch bring
it under “ON” condition.
2. Secondary interlock switch and interlock
monitor switch.
When the door is closed, the hook pushes the lock
lever downward. The lock lever presses the button of the
interlock monitor switch to bring it under “OFF” condition
and presses the button of the secondary interlock switch
to bring it under “ON” condition.
3. Adjustment steps
(1) Loosen the one mounting screw.
(2) Adjust interlock switch assembly position.
(3) Make sure that lock lever moves smoothly after adjustment is completed.
(4) Tighten completely one mounting screw.
Microwave emission test should be performed after adjusting interlock mechanism.
If the microwave emission exceed 4mW/cm
2
, readjust interlock mechanism.
NOTE
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

18
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 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 then check continuity with the AC plug removed. To do otherwise may result in a false reading or damage to your meter.
(TROUBLE 1) Door shut, timer set, but no cooking takes place.
Does the fan motor work when you
shut the door and turn the timer?
Does the
fuse blow?
Check continuity of interlock
monitor switch with door shut.Replace primary, secondary
interlock switch and interlock
monitor switch.
Replacefuseand check
continuity of both interlock
switch's contact and monitor
switch's contact with door
partially open until monitor
switchcontact.
Replace primary, secondary
interlock switch and interlock
monitor switch.
Disconnect one side of the
lead wire connected from
transformer to the high voltage
capacitor, and operate oven.
Replacehigh
voltage
capacitor.
Replacehigh
voltagetransformer
Ifoutlethas proper voltage,
checkcontinuityof power.Replace power
supply cord.
YES (Refer to next page)
NO
NO
NO
YES Continuity
NOContinuity
NOContinuity
Both continuity
Normal
Fuse again

19
TROUBLE SHOOTING GUIDE
Does the fan motor work when you shut
the door and turn the timer?
Does the oven lamp light?
Does the turntable turn?Replace or repair oven lamp,
turntable motor.
If microwave do not oscillate,
check continuity of filament
of magnetron.
Normal
reading should
be approx. 0
Ω
Check continuity filament
tap (3.3V) of high voltage.
Replace high
voltage
transformer.
Check the diode for
continuity in the reverse and
normal directions.
Replace high
voltage diode.
Replace
magnetron.
Replace
magnetron.
Meter with 6V or higher
voltage batteries should
be used to check the normal
direction resistance of
the diode.
Check the isolation of
filament winding of high
voltage transformer.
Replace high
voltage
transformer.
Good
NO Good
Poor continuity
NO
ContinuityNO Continuity
Continuity
Continuity
Continuity in
the reverse
direction.
NO
YES
YES