Domar SM256G User manual

Service Manual
Microwave Oven
Model: SM256G
SM356G
DOMAR S.A.
Mar. 2002
DOMAR S.A.
✔ 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
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 power to the microwave oven for any service test or inspection within the
microwave generating compartments, check the magnetron, wave huide 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
SAFETY AND PRECAUTIONS..................................................................................................................................2
1. FOR SAFE OPERATION .....................................................................................................................2
2. FOR SAFE SERVICE PROCEDURES ................................................................................................2
SPECIFICATIONS......................................................................................................................................................3
EXTERNAL VIEW......................................................................................................................................................4
1. OUTER DIMENSION............................................................................................................................4
2. FEATURE DIAGRAM...........................................................................................................................5
3. CONTROL PANEL...............................................................................................................................6
INSTALLATION .........................................................................................................................................................7
OPERATIONS AND FUNCTIONS.............................................................................................................................8
DISASSEMBLY AND ASSEMBLY............................................................................................................................9
INTERLOCK MECHANISM AND ADJUSTMENT...................................................................................................18
TROUBLE SHOOTING GUIDE................................................................................................................................20
MEASUREMENT AND TEST...................................................................................................................................24
1. MEASUREMENT OF THE MICROWAVE POWER OUTPUT ...........................................................24
2. MICROWAVE RADIATION TEST......................................................................................................25
3. COMPONENT TEST PROCEDURE..................................................................................................26
WIRING DIAGRAM..................................................................................................................................................27
PRINTED CIRCUIT BOARD....................................................................................................................................28
1. CIRCUIT CHECK PROCEDURE .......................................................................................................28
2. PCB CIRCUIT DIAGRAM...................................................................................................................31
3. P.C.B. LOCATION NO. ......................................................................................................................32
EXPLODED VIEW AND PARTS LIST.....................................................................................................................34
1. DOOR ASSEMBLY ............................................................................................................................34
2. CONTROL PANEL ASSEMBLY.........................................................................................................34
3. TOTAL ASSEMBLY............................................................................................................................34

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’, 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
NOTE : This oven is designed for counter-top use only.

3
SPECIFICATIONS
MODEL SM 256G SM 356G
POWER SUPPLY 230~, 50Hz SINGLE PHASE WITH EARTHING
MICROWAVE 1200W 1350W
POWER CONSUMPTION GRILL 1050W 1050W
COMBINATION 2200W 2350W
MICROWAVE ENERGY OUTPUT 800W 950W
MICROWAVE FREQUENCY 2450 MHz
OUTSIDE DIMENSIONS(WXHXD) 465X279X365mm 495X294X392mm
(18.3X11.0X14.4 in) (19.5X11.6X15.4 in)
CAVITY DIMENSIONS(WXHXD) 290X220X306mm 320X244X338mm
(11.4X8.7X12.0 in) (12.6X9.6X13.3 in)
NET WEIGHT APPROX. 14Kg(30.9 lbs) APPROX. 16Kg(35.3 lbs)
TIMER 59 min. 90 sec.
FUNCTION SELECTIONS MICROWAVE / GRILL / COMBINATION
POWER SELECTIONS 5 LEVELS
CAVITY VOLUME 0.7 Cu. Ft. 0.9 Cu. Ft.

4
EXTERNAL VIEW
1. OUTER DIMENSION
SM 256G/SM356G
365/392465/495
279/294

5
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. SEFETY INTERLOCK SYSTEM
6. METAL RACK
7. COUPLER - This fits over the shaft in the center of the ovens cavity floor. This is to remain in the oven
for all cooking.
8. ROLLER GUIDE - This must always be used for cooking together with the glass cooking tray.
9. GLASS COOKING TRAY - Made of special heat resistant glass. Food in a proper receptacle is placed
on this tray for cooking.
10. DOOR VIEWING SCREEN - Allows viewing of food. The screen is designed so that light can pass
through, but not the microwave.
11. 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 immediately stop operating.
2. FEATURE DIAGRAM
SM 256G/SM356G
15
7
9
0q
2 3 4
6
8

6
1. Display - Cooking time, power level, indicators and present time are displayed.
2. Grill/Combi - Used to cook grill/combi.
3. Potencia/Descongelar - Used to set power level. Used to defrost foods by weight or time.
4. Auto cocción - Used to cook using a program or to reheat.
5. Inicio - Used to start the oven operation and also increase the reheat time by 30 seconds.
6. Stop/Borrar - Used to stop the oven operation or to erase all entries.
7. Reloj - Used to set clock.
8. Dial Knob - Used to set the time and weight.
3. CONTROL PANEL
SM 256G/SM356G
M/O DESC. GRILL COMBI
GRILL/COMBI
POTENCIA/
DESCONGELAR
RELOJ
STOP/
BORRAR
PESO/TIEMPO
INICIO
1. Plato principal
2. Sopa
3. Bebidas
4. Verduras frescas
g
AUTO COCCION 4
2
3
7
1
6
5
8

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 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 11 amperes, 230 Volts, 50 Hz.
•Power supply cord is about 1.4 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 reparied with cable of same type.
Such a cable can be purchased from DAEWOO and must be installed by 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.
EARTHING INSTRUCTIONS
This appliance must be earthed. In the event of an electrical short circuit, earthing reduces the risk of the electric
shock by providing an escape wire for the electric current. This appliance is equipped with a cord having a
earthing wire with a earthing plug. The plug must be plugged into an outlet that is properly installed and earthed.
WARNING : 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.

8
OPERATION 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 or a button 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 or button is touched during the oven operation, the oven stops cooking and all
information retained.
To erase all infomation (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.
12. When using the GRILL or COMBI mode;
•Do not open the door so often, the temperature inside the oven derease 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
handling 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.
*A : KOG-371G/H0S, KOG-391G/H0S
*B : KOG-371R0S, KOG-391R0S, KOG-374R/375R0S
Touch Power pad Power level (Display) Approximate Percentage of Power
or button A B A B
Once P-H1 P-HI 100% 100%
Twice P-90 P-80 90% 80%
3 times P-80 P-60 80% 60%
4 times P-70 P-40 70% 40%
5 times P-60 P-20 60% 20%
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% —
Make the oven is properly installed and plugged into the electrical outlet.

9
DISASSEMBLY AND ASSEMBLY
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 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, 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 insulted
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.
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.
CAUTION : Service personnel should remove their watches whenever working close to or replacing 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-HV Transformer,
Magnetron, HV Capacitor, HV Diode. HV Fuse.

10
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 for reassembly.
NOTE : After replacing the door assembly, perform a check of correct alignment with the hinge and cavity
front plate.

11
SM 256G
SM 356G
A06
A05
A04
A02
A01
A03
A07
A08
REF. NO PART CODE PART NAME DESCRIPTION QTY REMARK
A01 3512203860 FRAME DOOR ABS SG-175 1
A02 3517005630 BARRIER-SCREEN*0 SAN 1
A03 3515204100 SUPPER HINGE*T AS KOR-63150S 1
A04 3511705500 DOOR WELD AS KOR-61150S 1
A05 3517002800 BARRIER-SCREEN*I POLYESTER T0.1 1
A06 3512300200 GASKET DOOR PP 1
A07 3513100700 HOOK POM 1
A08 3515101300 SPRING HOOK PW1 1
REF. NO PART CODE PART NAME DESCRIPTION QTY REMARK
A01 3512204170 FRAME DOOR ABS SG-175 1
A02 3517005740 BARRIER-SCREEN*0 ACRYL 1
A03 3515204100 SUPPER HINGE*T AS KOR-63150S 1
A04 3511705620 DOOR WELD AS KOR-81250S 1
A05 3517002900 BARRIER-SCREEN*I POLYESTER T0.1 1
A06 3512300400 GASKET DOOR PP 1
A07 3513100700 HOOK POM 1
A08 3515101300 SPRING HOOK PW1 1
3. TO REMOVE DOOR PARTS.
SM 256G/SM356G
✔ 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)

12
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 supporter barrier screen outer from door frame.
7) Remove the barrier screen outer from door frame.
8) 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’.
•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
B
NOTE : A small gap may be acceptable if the microwave leakage does not exceed 4mW/cm2.

13
SM 256G
SM 356G
B09B08B07B06B05B04B03B02B01
REF. NO PART CODE PART NAME DESCRIPTION QTY REMARK
B01 3515501540 WINDOW DISPLAY PMMA 1
B02 3516723730 CONTROL PANEL ABS SG-175 1
B03 3516907530 BUTTON FUCTION *A ABS SG-175 1
B04 3516907540 BUTTON FUCTION *B ABS SG-175 1
B05 3513405240 KNOB VOLUME ABS 1
B06 PKBPMSZ300 PCB SUB AS KOG-373R0S 1
B07 7621301011 SCREW TAPPING T2 PAN 2X10 PW MFZN 4
B08 PKMPMSZ600 PCB MAIN AS KOG-373R0S 1
B09 7122401211 SCREW TAPPING T2S TRS 4X12 MFZN 3
REF. NO PART CODE PART NAME DESCRIPTION QTY REMARK
B01 3515501540 WINDOW DISPLAY PMMA 1
B02 3516723730 CONTROL PANEL ABS SG-175 1
B03 3516907530 BUTTON FUCTION *A ABS SG-175 1
B04 3516907540 BUTTON FUCTION *B ABS SG-175 1
B05 3513405240 KNOB VOLUME ABS SG-175 1
B06 PKBPMSZ300 PCB SUB AS KOG-373R0S 1
B07 7621301011 SCREW TAPPING T2 PAN 2X10 PW MFZN 4
B08 PKMPMST500 PCB MAIN AS KOG-393R0S 1
B09 7122401211 SCREW TAPPING T2S TRS 4X12 MFZN 3
5. TO REMOVE CONTROL PANEL PARTS.
SM 256G/SM356G
✔ 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)

14
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 four screws which secure the PCB assembly to control panel.
4) Disconnect membrane tail from the connector of the PCB assembly.
5) Detach membrane from the control panel.
6) Remove door open button and button spring from the control panel.
7) 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 H.V.diode from the capacitor holder.
3) Reverse the above steps for reassembly.
• High voltage circuit wiring
7. To remove magnetron.
1) Remove a 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/cm
2
for a fully assembled oven with door normally closed.

15
8. To remove wind guide assembly.
1) Remove a screw for earthing.
2) Remove the noise filter from the wind guide.
3) Remove a screw which secure the wind guide assembly.
4) Draw forward the wind guide assembly.
5) Pull the fan from the motor shaft.
6) Remove two screws which secure the motor shaded pole.
7) Remove the motor shaded pole.
8) 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
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 assmbly.
(1) Remove the three nuts.
(2) Remove the insulator heater assembly.
(3) Reverse the above steps for reassembly.

17
REF. NO PART CODE PART NAME DESCRIPTION QTY REMARK
C01 7392500008 NUT HEX 6N-2-5 SUS 1
C02 3515000600 SPACER INSULATOR *I C377BD 2
C03 3513301100 INSULATOR HEATER SPP T0.8 1
C04 3512803400 HEATER 230V 1000W 1R67994001 1
C05 7002500613 SCREW MACHINE TRS 5X6 MFCR 1
C06 7002400413 SCREW MACHINE TRS 4X4 MFCR 2
12. To remove heater parts.
✔ 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)

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.
(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
minitor switch to bring it under NO condition and presses the button of the secondary interlock switch to bring it under
ON condition.
(3) Adjustment steps
a) Loosen the one mounting screw.
b) Adjust interlock switch assmbly position.
c) Make sure that lock lever moves smoothly after adjustment is completed.
d) Tighten completely one mounting screw.
ADJUSTMENT :
Interlock monitor switch
When the door is closed, the interlock monitor switch should be changed(NO condition) before other switches
are closed.
When the door is opened, the interlock monitor switch should be changed(NC condition) after other switches are
opened.
NOTE : Microwave emission test should be performed after adjusting interlock mechanism. If the microwave
emission exceed 4 mW/cm
2
, readjust interlock mechanism.

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
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
minitor switch to bring it under NO condition and presses the button of the secondary interlock switch to bring it under
ON condition.
(3) Adjustment steps
a) Loosen the one mounting screw.
b) Adjust interlock switch assmbly position.
c) Make sure that lock lever moves smoothly after adjustment is completed.
d) Tighten completely one mounting screw.
ADJUSTMENT :
Interlock monitor switch
When the door is closed, the interlock monitor switch should be changed(NO condition) before other switches
are closed.
When the door is opened, the interlock monitor switch should be changed(NC condition) after other switches are
opened.
NOTE : Microwave emission test should be performed after adjusting interlock mechanism. If the microwave
emission exceed 4 mW/cm
2
, readjust interlock mechanism.