Daewoo KOG-3885 User manual

Service Manual
Microwave Oven
Model:KOG-3885
DAEWOO ELECTRONICS CO., LTD.

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PRECAUTIONS TO BE OBSERVED BEFORE AND
DURING SERVICING TO AVOID POSSIBLE
EXPOSURE TO EXCESSIVE MICROWAVE ENERGY
(a) Do not operate or allow the oven to be operated with the door open.
(b) Make the following safety checks on all ovens to be serviced before activating the magnetron
or other microwave source, and make repairs as necessary: (1) Interlock operation, (2) proper
door closing, (3) seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or
loosening of hinges and latches, (5) evidence of dropping or abuse.
(c) Before turning on 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, integrity, 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.
TABLE OF CONTENTS
PROPER USE AND SERVICE PRECAUTIONS 3
SPECIFICATIONS 4
FEATURES DIAGRAM 5
INSTALLATION 6
OPERATION 7
MEASUREMENT OF THE MICROWAVE OUTPUT POWER 8
MICROWAVE RADIATION TEST 9
WIRING DIAGRAM 10
CIRCUIT DESCRIPTION 12
PRECAUTIONS FOR DISASSEMBLY AND REPAIR 14
DISASSEMBLY AND ASSEMBLY 15
INTERLOCK MECHANISM 21
TROUBLE SHOOTING GUIDE 23
COMPONENT TEST PROCEDURE 25
SAFETY INTERLOCK CONTINUITY TEST 26
EXPLODED AND PARTS LIST 27

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CAUTION : This Device is to be Serviced Only by Porperly Qualified Service Personnel. Consult the
Service Manual for Proper Service Procedures to Assure Continued Compliance with the
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 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 SECURE. NEVER OPERATE THE DEVICE WITHOUT A
MICROWAVE ENERGY ABSORBING LOAD ATTACHED. NEVER LOOK INTO AN OPEN
WAVEGUIDE OR ANTENNA WHILE THE DEVICE IS ENERGIZED.
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 seal area and oven cavity surface 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 ascertained oven unit is found to have excessive emission level 5mW/cm
2
, the service person should:
(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.
PROPER USE AND SERVICE PRECAUTIONS

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SPECIFICATIONS KOG-3885
274
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Item Specification
POWER SUPPLY 230V~50HZ, SINGLE PHASE WITH EARTHING
MICROWAVE1350 W
MICROWAVEGRILL1050 W
COMBINATION2350 W
MICROWAVE ENERGY OUTPUT900 W
MICROWAVE FREQUENCY2450 MHz
OUTSIDE DIMENSIONS (WXHXD)495X289X382 mm
CAVITY DIMENSIONS (WXHXD)320X330X225 mm
NET WEIGHT16.5 Kg
TIMER 35 min. DUAL SPEED
FUNCTION SELECTIONS MICROWAVE/GRILL/COMBINATION
MICROWAVE POWER LEVELS 3 LEVELS
* Specifications subject to change without notice.
(382)(495)
(289)

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¤Saftey Interlock System.
¤Ł Door Viewing Screen - Allows viewing of food, the screen is designed so that light can pass
through, but not the microwave.
¤Ø Door Hook - When the door is closed, it will automatically shut. If the door is opened while the oven
is operating, the magnetron will immediately stop operating.
¤Œ Oven Cavity
¤º Door Seal - Door seal maintains the microwave energy within the oven cavity and prevents
microwave leakage.
¤Glass Cooking Tray - Made of special heat resistant glass. Food in a proper receptacle is placed
on this tray for cooking.
¤Roller Guide - This must always be used for cooking together with the glass cooking tray.
¤Coupler - this fits over the shaft in the center of the oven’s cavity floor. This is to remain in the oven
for all cooking.
¤Knob V.P.C - Used to select a microwave power level.
¤Knob Timer - Used in setting cooking time for all functions.
¤æ Door Release Button - By pushing this button the latch system cut off all circuits and stops the
oven before the door is opened.
¤Reflector (Insulator Heater)
¤Heating Element
¤Metal Rack
FEATURES DIAGRAM
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41
9
6
7
212 13
14
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11
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1. Steady, flat location.
This microwave oven should be set on a steady, flat surface.
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, or
antenna, 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 12 amperes, 230V 50Hz.
Use a receptacle that will accept the earth prong.
• Voltage Warning
The voltage used must be the same as specified on this Microwave 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 Microwave Oven will a voltage or amperage
fuse other than those specified.
• Power supply cord is about 1.0 meters long. Do not use an extension cord.
If the supply cord is damaged, it must be replaced by the manufacturer or its service agent or a similarly
qualified person in order to avoid a hazard;
INSTALLATION
6. Examine the oven after unpacking for any damage such as:
Dents, A misaligned door, Broken door, A dents in cavity.
If any of the above are visable, do not install this oven.
CAUTION : Do not under any circumstances cut or remove the round earthing prog from this pulg.
CAUTION : Maintenances works like the replacing of the power cable must be made by a technician
qualified of the after-sales-services.
WARNING : This appliance must be earthed.
This wires in this mains lead are coloured inaccordance 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’ or by the earth symbol or 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

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OPERATION
1. Connect the mains lead to an electrical socket-outlet.
2. After placing the food in a suitable utensil, open the oven door and put it on the glass turntable, Glass turntable
must always be in place during cooking.
In case the oven is operated in the grill mode, use the Metal Rack and place food on the metal Rack.
3. Shut the door.
Make sure that it is firmly closed.
4. How to set each function.
To set MICROWAVE Cooking.
• Set the variable POWER SELECTOR to desired power level.
To set GRILL Cooking
• Set the POWER SELECTOR to the (gril) position.
To set COMBI Cooking
• Set the POWER SELECTOR to the (combi) position.
5. Set the time control by turning the timer knob and then the oven operate inselected cooking mode.
If turing the timer knob for less than 2 minutes, turn it past 2 minutes and then back to the desired time.
6. The oven will be turned off automatically when the timer point to “OFF”.
Then take out foods.
• To prevent the oven operating with the door open, your is fitted with safety door interlock switches.
If you wish to inspect the food during the cooking time, simply open the door. The oven will auto matically stop the
cooking. To continue cooking, you simply close the door.
• If you wish to sotp the cooking during the cooking simply turn the timer knob the point “OFF” Cooking can be reset at
any time during the cooking cycle by only turning the timer knob.
• Do not let the timer continue to operate after removing food.
7. NOTE : When using the GRILL (KOG:368(9)OS) mode;
• Do not open the door so often, the temperature inside the oven decrease and the cooking may not complete in setting time.
• Never touch the oven window and metal interior of the oven when taking food in and out, because of 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.
COOKING UTENSILS
Before use, the user should check that tensils are suitable for use in microwave ovens.
SYMBOL POWER LEVLE POWER
DEFROST 33%
MED-HIGH 77%
HIGH 100%
Material Grill Microwave
cooking cooking
Glass (general) NO Yes(1)
Glass (heat resistant) Yes Yes
Glass-ceramic and ceramic(heat resistnat) Yes Yes(1)
Earthenware Yes Yes
China(heat resistant) Yes Yes
Plastic(general) No Yes(2)
Plastic(heat resistant) Yes(2) Yes(2)
Aluminium foil containers/aluminium foil Yes Yes(3)
Metal baking tins Yes(4) No
Metal (pots. pans, etc) Yes No
Paper No Yes
1. Without metal parts or metal trims.
2. Some plastics are heat-proof only to certain temperatures. Check carefully!
3. It is possible to use aluminium foil to shield delicate areas of food (this prevents over-cooking).
4. Metal tins can be used in the combination methods, however if these are very deep, they will greatly reduce the efficiency, as
metal shields the microwave energy from the food.

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MEASUREMENT OF THE MICROWAVE OUTPUT POWER
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. Microwave power output measurement is made with the microwave oven supplied at rated voltage and operated
at its maximum microwave power setting with a load of 1,000±5cc of potable water.
2. The water is contained in a cylindrical borosilicate glass vessel having a maximum material thickness of 3 mm
and an outside diameter of approximately 190 mm.
3. The oven and the empty vessel are at ambient temperature prior to the start of the test.
The initial temperature of the water is 10±2˚C(50±3.6˚F).
It is measured immediately before the water is added to the vessel. After addition of the water to the vessel, the
load is immediately placed on the center of the shelf which is in the lowest normal position.
4. Microwave power is switched on.
5. Heating time should be exactly 52(800W) and 47(900W)
seconds.
Heating time is measured while the microwave generator is
operating at full power.
The filament heat-up time for magnetrons is not included.
6. The initial and final water temperatures are selected so that
the maximum defference between the ambient and final
water temperature is 5K.
7. The microwave power output P in watts is calculated from the following formula:
• ∆ T is actual temperature rise.
• t is the heating time.
The power measured should be 800W±10%(G-3685) and 900W±10%(G-3885).
CAUTION :
1. Water load should be measured exactly to 1 liters.
2. Input power voltage should be exactly 230 volts as specified.
3. Ambient temperature should be 20±2˚C (68±3.6˚F)
Water Load
Tray
P = 4187 X ∆T/t

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MICROWAVE RADIATION TEST
WARNING
• Make sure to check the microwave leakage before and after repair or adjustment.
• Always, start measuring of an unknown field to assure safety for operating personnel from microwave energy.
• Do not place your hands into any suspected microwave radiation field unless the safe density level is known.
• Care should be taken not to place the eyes in direct line with the source of microwave energy.
• Slowly approach the unit under test until the radiometer reads an appreaciable microwave leakage from the unit
under the test.
Procedure
A) Prepare Microwave Energy Survey Meter, 600cc glass beaker, glass thermometer 100˚C or 212˚F.
B) Pour 275cc±15cc of tap water initially at 20±5˚C(68±9˚F) in the 600cc beaker with an inside diameter of approx.
9.5cm (3.5 in).
C) Place it at the center of the tray and set it in a cavity.
D) Close the door and operate the oven.
E) Measure the leakage by using microwave energy survery meter with dual ranges, set to 2450 MHz.
- Measured radiation leakage must not exceed the values prescribed below.
• Leakage for a fully assembled oven with door normally closed must be less than 4mW/cm
2
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- When measuring the leakage, always use the 2 in (5cm) space cone with probe. Hold the probe perpendicular
to the cabinet, door. Place the space cone of the probe on the door, cabinet, door seam, door viewing screen,
the exhaust air vents and the suction air vents.
- Measuring should be in a counter-clockwise
direction at a rate of 1 inch/sec. If the leakage of the
cabinet door seam is unkow, move the prove more
slowly.
- 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 inches from any metal.
If it does, erroneous reading may result.
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WIRING DIAGRAM(SLOW ACTING RELAY)