Daewoo KOR-61151 User manual

Service Manual
Microwave Oven
KOR-61155
KOR-61151
DAEWOO ELECTRONICS CO., LTD.

2
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)Mark 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)
evidence of dropping or abuse.
(c) Before turning on microwave power for any service test or inspection within the microwave generating com-
partments, 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
PROPER USE AND SERVICE PRECAUTIONS 3
SPECIFICATIONS 4
FEATURE DIAGRAM 5
INSTALLATION 6
OPERATION 7
MEASUREMENT OF THE MICROWAVE OUTPUT POWER 8
MICROWAVE RADIATION TEST 9
KOR-6115 WIRING DIAGRAM 10
KOR-61151 WIRING DIAGRAM 11
CIRCUIT DESCRIPTION 12
PRECAUTIONS FOR DISASSEMBLY AND REPAIR 14
DISASSEMBLY AND ASSEMBLY 15
INTERLOCK MECHANISM 20
TROUBLE SHOOTING GUIDE 22
COMPONENT TEST PROCEDURE 24
EXPLODED VIEW AND PARTS LIST 26

3
PROPER USE AND SERVICE 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 even 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 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 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.
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

4
SPECIFICATIONS
ITEM SPECIFICATION
POWER SUPPLY 120V~60Hz, SINGLE PHASE WITH EARTHING
POWER CONSUMPTION 920 W
MICROWAVE OUTPUT POWER 600 W (IEC 705) (FULL MICROWAVE POWER)
FREQUENCY 2450 MHz
OUTPUT DIMENSIONS (W X H X D) 465 X 274 X 360 mm (18.3 X 10.8 X 14.2 in.)
CAVITY DIMENSIONS (W X H X D) 290 X 200 X 290 mm (11.4 X 7.9 X 11.4 in)
NET WEIGHT APPROX. 12.5 kg (27.6 Ibs.)
TIMER 35 min. DUAL SPEED
POWER SELECTIONS 5 LEVELS
CAVITY VOLUME 0.64 Cu.Ft.
* Specifications are subject to change without notice.
465 360
274

¤Safety 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.
5
FEATURES DIAGRAM
241
11
6
7
8
35
9
12

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 15 amperes, 120 Volts, 60Hz grounded outlet.
• Power supply cord is about 1.0 meters long.
1. A short power-supply cord is poovided 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,
and (3) the longer cord should be arranged so that will not drape over the countertop 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, A dents in cavity.
If any of the above are visible, DO NOT INSTALL, and notify dealer immediately.
6
INSTALLATION
When use 3-pronged plug
3-prong Receptacle
Receptacle
Box cover
3-prong plug
When use a grounding adaptor, make
usre the receptacle box is fully
grounded
Grounding Lead
Receptacle Box cover
Grounding Adaptor
Receptacle

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 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 mecha-
nisms stop microwave power and 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 turns off.
¢”Oven light turns off.
If additional cooking time is needed and the door has
not been opened, the oven will automatically start
when the Timer is reset.
7
OPERATION
Variable Power Cooking
ON and OFF cycle time of mechanicial V.P.C. switch is 30 seconds.
When the V.P.C. knob is set to the desired position and timer knob turns to the desired position, the V.P.C. switch
has a cycle (ON/OFF time (sec)) listed below.
NOTE :
1. When setting Timer for less than 2 minutes, turn
the Timer past 2 minutes and then return to the
correct timer setting.
2. Various clicking noises may be heard when turning
the V.P.C. knob. This is normal and does not affect
the operation of your microwave oven.
Variable power setting
(HIGH)
(MED HIGH)
(MEDIUM)
(DEFROST)
(WARM)
ON/OFF time (sec)
30/0
23.2/6.8
16.5/13.5
9.8/20.2
5/25
Power
100%
77%
55%
33%
17%
012
3
4
5
6
10
15
20
25
30
35

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 49 seconds.
Heating time is measured while the microwave genera-
tor 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 difference between the ambient and
final water temperatures 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 600W¡10.0%.
P = 4187 X ∆T/t
8
MEASUREMENT OF THE MICROWAVE OUTPUT POWER
Water Load
Tray
CAUTION :
1. Water load should be measured exactly to 1 liters.
2 Input power voltage should be exactly 230V as specified.
3. Ambient temperature should be 20¡2˚C(68¡3.6˚F)

WARNING
• Make sure to check the microwave leakage before and after repair of 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 appreciable 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.
ƒ¡ 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
.
ƒ¡When measuring the leakage, always use the 2 in (5cm) 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 seam, door viewing screen, the
exhaust air vents and the suction air vents.
ƒ¡Measuring should be in a counter-clockwise direc-
tion at a rate of 1 inch/sec. If the leakage of the
cabinet door seam is unknow, move the probe more
slowly.
ƒ¡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.
9
MICROWAVE RADIATION TEST

10
KOR-6115 WIRING DIAGRAM
POWER SUPPLY :
PRIMARY INTERLOCK SWITCH(UPPER)
TIMER SWITCH
TIMER ASS'Y
V.P.C
.
FUSE
INTERLOCK MONITOR SWITCH
HIGH VOLTAGE TRANSFORMER
H.V. CAPACITOR
H.V. DIODE
MAGNETRON
WH
LIVE RD
BK
WH
NEUTRAL
WH
BK
BL
GY
GYGY
GY
GY GY
CL GM FM
SECONDARY INTERLOCK SWITCH
NOTE : RD : RED
WH: WHITE BK : BLACK GN : GREEN BR : BROWN
OR : ORANGE BL : BLUE GY : GRAY GE : GREEN/YELLOW
CL : CAVITY LAMP FM : FAN(BLOWER) MOTOR GM : GEARED MOTOR TM : TIMER MOTOR V.P.C. : VARIABLE POWER CONTROLLER
[ CONDITION ] DOOR : CLOSED TIMER : ON V.P.C. : HIGH
RD RD
OR OR
SINGLE PHASE
~
ONLY
2
M
13
TM
GN

11
KOR-61151 WIRING DIAGRAM
POWER SUPPLY :
PRIMARY INTERLOCK SWITCH(UPPER)
TIMER SWITCH
TIMER ASS'Y
V.P.C
.
CAVITY THERMOSTAT
INTERLOCK MONITOR SWITCH
HIGH VOLTAGE TRANSFORMER
H.V. CAPACITOR
H.V. DIODE
MAGNETRON
WH
RD BK
WH
GN
WH BK
BL
GY
GYGY
GY
GY GY
CL GM FM
SECONDARY INTERLOCK SWITCH
NOTE : RD : RED
WH: WHITE BK : BLACK GN : GREEN BR : BROWN
OR : ORANGE BL : BLUE GY : GRAY GE : GREEN/YELLOW
CL : CAVITY LAMP FM : FAN(BLOWER) MOTOR GM : GEARED MOTOR TM : TIMER MOTOR V.P.C. : VARIABLE POWER CONTROLLER
[ CONDITION ] DOOR : CLOSED TIMER : ON V.P.C. : HIGH
RD RD
OR OR
SINGLE PHASE
~
ONLY
2
M
13
TM
FILTER ASS’Y
FUSE
LL
NN
GN

1. When the food is placed in the oven cavity and door is closed.
• The contact of the interlock monitor switch open.
• The contacts of the primary interlock switch and secondary interlock switch close.
2. When the timer is set to the time desired.
• The contact of the timer switch close.
• Oven lamp turn on.
• 120V AC is applied to the high voltage transformer.
• Turntable motor start rotating and glass tray rotating.
• Fan motor rotating and cools the magnetron by blowing air.
• Timer motor operating and point to passing cooking time.
• 3.3 Volts AC is generated from the filament winding of the high voltage transformer. This filament voltage is applied to
the magnetron to heat the magnetron filament through two noise preventing choke coils.
• A high voltage of 2000 Volts AC is generated in the secondary of high voltage transformer and this secondary voltage
is increased by the action of the diode and the charging of the high voltage capacitor. This resultant D.C voltage is then
applied to the anode of the magnetron. As shown in Fig. 2 the first half cycle of the high voltage produces in the high
voltage transformer secondary charges the high voltage capacitor. Current flow is in the direction of the dotted-line
during the second half cycle, the voltage produced by the transformer secondary, and the charge of the high voltage
capacitor are combined and applied to the magnetron as shown by the solid line so that oscillations begins.
The disturbance wave generated by the magnetron is prevented by the choke coils of 1.5µH, filter capacitors of 500pF
and the magnetron’s shielded case so that TV and radio programs are not impaired by noise.
12
CIRCUIT DESCRIPTION
TM
TM
CL
CL
GM
GM
FM
FM
Timer motor Cavity lamp Geard motor Fan motor
Fig. 1
15A Fuse
Primary
Interlock
Switch
Interlock
Monitor
Switch
Timer
Switch
Secondary
Interlock
Switch

13
HIGH VOLTAGE
TRANSFORMER
H.V.
CAPACITOR
H.V.
FUSE
H.V. DIODE
Fig. 2
MAGNETRON
3. When the door is opened during cooking.
• Primary interlock switch and secondary interlock switch open to cut off the primary voltage to the high voltage
transformer to stop microwave oscillation.
• Fan motor, timer motor and turntable motor stop rotating.
• Oven lamp turn off.
• As soon as the door is opened, monitor switch close (NC) to create the short circuit.
If the contacts of primary interlock switch and secondary interlock switch are both malfunction, the 15A fuse blows open
due to the large current surge caused by monitor switch activation.

ƒ¡Cautions to be observed when trouble shooting.
Unlike many other appliances, the microwave oven is a 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 golves 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 make sure it is earthed
properly before beginning repair work.
2. Warning about the electric charge in the high volt-
age capacitor.
For about 30 seconds after the operation stopped, and
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 screw
driver to discharge.
(4)When the 15A fuse is blown out due to the operation of the monitor switch; replace primary, secondary interlock switch
and monitor switch.
Refer to next page for the necessary adjustment.
(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.
14
PRECAUTIONS FOR DISASSEMBLY AND REPAIR
CAUTION : Service personnel should remove their watches whenever working close to or repairing the magnetron.
WARNING : 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-H.V. Transformer, Magnetron, H.V.
Capacitor, H.V. Diode.

15
DISASSEMBLY AND ASSEMBLY
1. To remove cabinet
Remove three screws on cabinet back.
2. To remove door assembly
(1) Remove two screws ¤which secure the stopper
hinge top.
(2) Remove the door assembly ¤Ø from top plate of
cavity.
(3) Remove the above for reassembly.
3. To remove door parts
NOTE : After replacing the door perform a
check of correct alignment with the
hinge and cavity front face.
2
3
1
1 2 3 4 5 6
7
8

16
(1) Remove the gasket door ¤from door plate ¤Œ.
(2) Remove the barrier screen inner ¤ºfrom door plate ¤Œ.
(3) Remove the door frame ¤Łfrom door plate ¤Œ.
(4) Remove the stopper hinge top ¤Øfrom door plate ¤Œ.
(5) Remove the spring ¤and the hook ¤.
(6) Remove the barrier screen outer ¤from door frame ¤Ł.
(7) Remove 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’.
1) Loosen two screws on stopper hinge top, and
then push the door to contact the door seal to
oven front surface.
2) Tighten two screws.
(2) To reduce gap located on part ‘B’.
1) Loosen three screws on bottom hinge, and then
the door to contact the door seal to oven front
surface.
2) Tighten three screws.
(3) To reduce gap located on part ‘C’. (See Fig. A)
1) Loosen a screw on the interlock switch assembly located at the bottom of the oven body.
2) Draw the interlock switch assembly inward as possible to engage with hook on the door bottom.
3) Tighten a screw.
(4) To reduce gab located on part ‘D’.(See Fig. B)
1) Loosen a screw on the interlock switch assembly located at the top of the oven body.
2) Follow step (3) 2) and 3).
NOTE : A small gab may be acceptable if the microwave leakage does not exceed 4mW/cm
2
.
A D
CB
Hook
Secondary
Interlock
Switch
Mounting
Screw
Hook
Primary
Interlock
Switch
Fig. A Fig. B
Mounting Screw

17
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 ¤Łwhich secure the timer assembly ¤Ø.
(4) Remove the timer assembly ¤Ø.
(5) Pull out the timer knob ¤Œfrom the timer assembly ¤Ø.
(6) Pull out the timer coupler ¤ºfrom the timer assembly ¤Ø.
(7) Remove the screw ¤which secure the V.P.C. coupler ¤.
(8) Pull out the V.P.C coupler ¤and V.P.C knob ¤from the control panel.
(9) Remove the door open button ¤and button spring ¤from the control panel.
(10) Reverse the above steps for reassembly.
8
7
Control Panel 6
5
4
3
2
1
10
9

6. To remove high voltage capacitor
(1) Remove a screw ¤which secure the grounding
ring ring terminal of the H.V. diode ¤Łand the
capacitor holder ¤Ø.
(2) Remove the H.V. diode ¤Łfrom the capacitor ¤Ø.
(4) Reverse the above steps for reassembly.
High voltage circuit wiring
7. To remove magnetron
(1) Remove four screws ¤which secure the
magnetron ¤Ł.
(2) Remove the magnetron ¤Ł.
(3) Reverse the above steps for reassembly.
18
1
2
3
Magnetron
H.V. Capacitor
H.V. Transformer
H.V. Diode

19
8. To remove fan motor assembly
(1) Remove two screws ¤which secure the back cover ¤Łfrom the cavity outer.
(2) Remove two screws ¤Øwhich secure the fan motor ¤Œfrom the back cover ¤Ł .
(3) Pull out the fan ¤ºfrom the fan motor ¤Œ .
(4) Reverse the above steps for reassembly.
9. To remove transformer
(1) Remove the two screws ¤holding the H.V. trans-
former ¤Ł.
(2) Remove the transformer ¤Ł.
(3) Reverse the above steps for reassembly.
Filament
Terminal
Cooling Fin
Magnetron
Antenna
Magnetron
Metallic
Gasket
Plate
Metallic Gasket Plate
Magnetron AntennaWave Guide
5
4
1
3
1
2
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/cm
2
for a fully assembled oven with door normally closed.

20
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 micro switch. Then the button of the primary interlock switch
bring it under on condition.
Adjustment 1
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 button.
INTERLOCK MECHANISM
1.2mm
Hook
Latch
Button
Mounting Screw
Primary Interlock Switch