Samsung MG7980W User manual

MICROWAVE OVEN
MG7980W
SERVICE
Manual
MICROWAVE OVEN CONTENTS
1. Precaution
2. Specifications
3. Operating Instructions
4. Disassembly and Reassembly
5. Alignment and Adjustments
6. Troubleshooting
7. Exploded Views and Parts List
8. PCB Diagrams
9. Schematic Diagrams

1. Precaution
1-1 Safety precautions ( )
Samsung Electronics 1-1
1. All repairs should be done in accordance
with the procedures described in this
manual. This product complies with
Federal Performance Standard 21 CFR
Subchapter J (DHHS).
2. Microwave emission check should be
performed to prior to servicing if the oven is
operative.
3. If the oven operates with the door open :
Instruct the user not to operate the oven and
contact the manufacturer and the center for
devices and radiological health immediatly.
4. Notify the Central Service Center if the
microwave leakage exceeds 5 mW/cm2
5. Check all grounds.
6. Do not power the MWO from a "2-prong"
AC cord. Be sure that all of the built-in
protective devices are replaced. Restore any
missing protective shields.
7. When reinstalling the chassis and its
assemblies, be sure to restore all protective
devices, including: nonmetallic control
knobs and compartment covers.
8. Make sure that there are no cabinet openings
through which people--particularly
children--might insert objects and contact
dangerous voltages. Examples: Lamp hole,
ventilation slots.
9. Inform the manufacturer of any oven found
to have emmission in excess of 5 mW/cm2,
Make repairs to bring the unit into
compliance at no cost to owner and try to
determine cause.
Instruct owner not to use oven until it has
been brought into compliance.
CENTRAL SERVICE CENTER
10. Service technicians should remove their
watches while repairing an MWO.
11. To avoid any possible radiation hazard,
replace parts in accordance with the wiring
diagram. Also, use only the exact
replacements for the following parts:
Primary and secondary interlock switches,
interlock monitor switch.
12. If the fuse is blown by the Interlock Monitor
Switch: Replace all of the following at the
same time: Primary, door sensing switch
and power relay, as well as the Interlock
Monitor Switch. The correct adjustment of
these switches is described elsewhere in this
manual. Make sure that the fuse has the
correct rating for the particular model being
repaired.
13. Design Alteration Warning:
Use exact replacement parts only, i.e.,
only those that are specified in the
drawings and parts lists of this manual.
This is especially important for the
Interlock switches, described above.
Never alter or add to the mechanical or
electrical design of the MWO. Any design
changes or additions will void the
manufacturer's warranty.10.Always unplug
the unit's AC power cord from the AC
power source before attempting to
remove or reinstall any component or
assembly.
14. Never defeat any of the B+ voltage
interlocks. Do not apply AC power to the
unit (or any of its assemblies) unless all
solid-state heat sinks are correctly installed.
15. Some semiconductor ("solid state") devices
are easily damaged by static electricity. Such
components are called Electrostatically
Sensitive Devices (ESDs). Examples include
integrated circuits and field-effect
transistors.
Immediately before handling any
semiconductor components or assemblies,
drain the electrostatic charge from your
body by touching a known earth ground.
16. Always connect a test instrument's ground
lead to the instrument chassis ground before
connecting the positive lead; always remove
the instrument's ground lead last.
Follow these special safety precautions. Although the microwave oven is completely safe during ordinary
use, repair work can be extremely hazardous due to possible exposure to microwave radiation, as well as
potentially lethal high voltages and currents.

17. When checking the continuity of the witches
or transformer, always make sure that the
power is OFF, and one of the lead wires is
disconnected.
18. Components that are critical for safety are
indicated in the circuit diagram by
shading, or .
19. Use replacement components that have the
same ratings, especially for flame resistance
and dielectric strength specifications. A
replacement part that does not have the
same safety characteristics as the original
might create shock, fire or other hazards.
1. High Voltage Warning
Do not attempt to measure any of the high
voltages--this includes the filament voltage
of the magnetron. High voltage is present
during any cook cycle.
Before touching any components or wiring,
always unplug the oven and discharge the
high voltage capacitor (See Figure 1-1)
2. The high-voltage capacitor remains charged
about 30 seconds after disconnection. Short
the negative terminal of the high-voltage
capacitor to the oven chassis. (Use a
screwdriver.)
3. High voltage is maintained within specified
limits by close-tolerance, safety-related
components and adjustments. If the high
voltage exceeds the specified limits, check
each of the special components.
1-2
Pretaution
Samsung Electronics
1-2 Special Servicing Precautions (Continued)
1-3 Special High Voltage Precautions
PRECAUTION
Servicemen should remove their watches whenever
working close to or replacing the magnetron.
PRECAUTION
There exists HIGH VOLTAGE ELECTRICITY with high
current capabilities in the circuits of the HIGH VOLTAGE
TRANSFORMER secondary and filament terminals. It is
extremely dangerous to work on or near these circuits
with the oven energized.
DO NOT measure the voltage in the high voltage circuit
including filament voltage of magnetron.
PRECAUTION
Never touch any circuit wiring with your hand nor with
uninsulated tool during operation.
H. V. Diode
Short
H. V. Capacitor
Touch chassis ground first then short to the high
voltage capacitor terminal by using screwdriver or
jumper wire.

2. Specifications
2-1 Table of Specifications
Samsung Electronics 2-1
MODEL MG7980W
ITEM
TIMER 99 MINUTES 99 SECONDS
POWER SOURCE 120V/60HZ, AC
POWER CONSUMPTION MICROWAVE : 1,400W
HEATER : 1,300W
OUTPUT POWER FROM 100W TO 1000W (10 LEVEL POWER)/(IEC-705 TEST PROCEDURE)
OPERATING FREQUENCY 2,450MHz
MAGNETRON OM75PH(31)ESS
COOLING METHOD COOLING FAN MOTOR
OUTSIDE DIMENSIONS 2121/32(W) x 1212/32(H) x 1715/32(D)
NET WEIGHT 44.1 lbs.
SHIPPING WEIGHT 50.7 lbs

3-1 Samsung Electronics
One
Minute
+
Help
Screen
Browner Popcorn
Diet
Cook
Frozen
Dinner
Custom
Potoato
Fresh
Vegetable
Baby
Food
Power
Level
Auto Start
Hold
Timer
More
Less
123
456
789
0
Auto
Defrost
Auto
Reheat
Clock
Sound
Pause
Cancel Start
One Minute + Button
Instant Cook Button
Browner Button
Auto Defrost Button Auto Reheat Button
Number Key Button
Start Button
Sound Button
Clock / Auto Start Button
Hold / Timer Button
Power Level Button
More / Less Button
Pause / Cancel Button
3. Operating Instructions
3-1 Control Panel
3-2 Features & External Views
Door Ventilation Hole Light Safety Interlock Holes
Heater
Control Panel
Open Door Push Button
Guide Roller
Metal Rack
Glass Tray
Door Latches
556mm
402mm
313mm
260mm
444mm
Help Screen Button

4. Disassembly and Reassembly
4-1 Replacement of Magnetron, Motor Assembly and Lamp
Samsung Electronics 4-1
Remove the magnetron including the shield case,
permanent magnet, choke coils and capacitors (all
of which are contained in one assembly).
1. Disconnect all lead wires from the magnetron
and lamp.
2. Remove the air cover.
3. Remove screws securing the magnetron to the
wave guide.
4. Take out the magnetron very carefully.
5. Remove tow screws from the back panel of fan
motor assembly.
6. Take out the fan motor assembly.
7. Remove the oven lamp by pulling out from hole
of air cover.
NOTE1: When removing the magnetron, make
sure that its antenna does not hit any
adjacent parts, or it may be damaged.
NOTE2: When replacing the magnetron, be sure
to remount the magnetron gasket in
the correct position and make sure the
gasket is in good condition.
1. Discharge the high voltage capacitor.
2. Disconnect all the leads.
3. Remove the mounting bolts.
4. Reconnect the leads correctly and firmly.
4-2 Replacement of High Voltage Transformer
Lamp
Cover Air
Magnetron H. V. Trans
H. V. Capacitor
Thermo S/W
Fan Motor
Bracket T.C.O
Magnetron
Screw
Bolts
PRECAUTION
Servicemen should remov their watches whenever working
close to or replacing the magnetron.
PRECAUTION
There exists HIGH VOLTAGE ELECTRICITY with high current capabilities in the circuits of the HIGH VOLTAGE
TRANSFORMER secondary and filament terminals. It is extremely dangerous to work on or near these circuits with the
oven energized.
DO NOT measure the voltage in the high voltage circuit including filament voltage of magnetron.
H. V. Trans

4-3 Replacement of Door Assembly
4-3-1 Removal of Door Assembly
4-2 Samsung Electronics
Remove screws securing the upper hinge and
lower hinge. Then remove the door assembly.
Insert flat screwdriver into the gap between Door
"A" and Door "C" to remove Door "C". Be careful
when handling Door "C" because it is fragile.
Following the procedure as shown in the figure,
insert and bend a thin metal plate between Door
"E" and Door "A" until you hear the 'tick' sound.
1. Insertion depth of the thin metal plate should be
0.5mm or less.
Remove pin hinge from Door "E"
Detach spring from Door "E" and key door.
4-3-2 Removal of Door "C"
4-3-3 Removal of Door "E"
Key Door Spring
Door "E"
Disassembly and Reassembly
Upper Hinge
Lower Hinge
Screw
Screw
Door "C"
Door "A"
Door "E"
4-3-4 Removal of Key Door & Spring

4-3-5 Reassembly Test
Samsung Electronics 4-3
1. Take out the glass tray and the guide roller from
the cavity.
2. Turn the oven upside down to replace the drive motor.
3. Remove a screw securing the drive motor cover
or disconnect the drive motor cover from base
plate by nipper.
4. Disconnect all the lead wires from the drive motor.
5. Remove screws securing the drive motor to the
cavity.
6. Remove the drive motor and the coupler.
7. When replacing the drive motor, be sure to
remount it in the correct position with the
coupler.
8. Connect all the leads to the drive motor.
9. Screw the drive motor cover to the base plate
with a screw driver.
1. Disconnect the oven from the power source.
2. When 20A fuse blows out by the operation of interlock monitor switch failure, replace the primary
interlock switch, door sensing switch, monitor switch and power relay.
3. When the above three switches operate properly, check if any other part such as the control circuit board,
blower motor or high voltage transformer is defective.
4-4 Replacement of Fuse
4-5 Replacement of Drive Motor
Disassembly and Reassembly
Screw
Drive Motor Cover Base Plate
Thermo
Switch
Drive Motor
After replacement of the defective component parts of the door, reassemble it and follow the instructions below for proper
installation and adjustment so as to prevent an excessive microwave leakage.
1. When mounting the door to the oven, be sure to adjust the door parallel to the bottom line of the oven
face plate by moving the upper hinge and lower hinge in the direction necessary for proper alignment.
2. Adjust so that the door has no play between the inner door surface and oven front surface. If the door
assembly is not mounted properly, microwave energy may leak from the space between the door and
oven.
3. Do the microwave leakage test.

4-6 Replacement of Control Circuit Board
4-6-1 Removal of Control Box Assembly
4-4 Samsung Electronics
1. Be sure to ground any static electric charge in
your body and never touch the control circuit.
2. Disconnect the connectors from the control
circuit board.
3. Remove screws securing the control box
assembly.
4. Remove the screw securing the ground tail of
the keyboard.
1. Pull the lever end of the plastic fastener and
remove the Flexible Printed Circuit(FPC) of
membrane panel.
2. Remove screws securing the control circuit
board.
3. Lift up the control circuit board from the Ass'y
control box.
4. When reconnecting the FPC connector, make
sure that the holes on the connector are properly
engaged with the hooks on the Plastic Fastener.
1. Window display should not be disassembled as
its mounting tabs will be broken. If repair work
is difficult, replace with Ass'y control panel.
2. The membrane key board is attached to the
escutcheon base with doublefaced adhesive
tape. Therefore, applying hot air such as using
of hair dryer is recommended for smoother
removal.
3. When installing new membrane key board,
make sure that the surface of escutcheon base is
cleaned sufficiently so that any problems
(shorted contacts or uneven surface) can be
avoided.
4-6-2 Removal of P.C.B Assembly
4-6-3 Removal of Window Display & Membrane Panel
Disassembly and Reassembly
Control Box
FPC Connector Screw
Screw
Membrane
Panel
Window
Display

Samsung Electronics
5. Alignment and Adjustments
5-1 High Voltage Transformer
5-2 Low Voltage Transformer
5-3 Magnetron
5-1
1. Remove connectors from the transformer terminals
and check continuity.
2. Normal resistance readings are as follows:
(Room temperature = 20˚C)
1. Continuity checks can indicate only an open
filament or a shorted magnetron. To diagnose an
open filament or shorted magnetron :
2. Isolate the magnetron from the circuit by
disconnecting its leads.
3. A continuity check across the magnetron filament
terminals should indicate one ohm or less.
4. A continuity check between each filament terminal
and magnetron case should read open.
1. The low voltage transformer is located on the
control circuit board.
2. Remove the low voltage transformer from the
PCB Ass'y and check continuity.
3. Normal resistor reading is shown in the table.
PRECAUTION
1. High voltage is present at the high voltage terminals during any cook cycle.
2. It is neither necessary nor advisable to attempt measurement of the high voltage.
3. Before touching any oven components or wiring, always unplug the oven from its power source and discharge the high voltage
capacitor.
Filament Terminals
Secondary
Terminal
Primary
Terminals
MODEL MG7980W
Secondary 75Ω ±10%
Filament Shows Continuity
Primary 0.30Ω ±10%
Resistance
DN-5574W CE-5574W
1~2(Input) 312.3Ω286.5Ω
4~5(Output17V) 11.22Ω9.245Ω
7~8(Output2.7V) 2.213Ω1.735Ω
Cooling Fins
Gasket Plate
Magnetron Antenna
Terminals

Samsung Electronics
5-4 High Voltage Capacitor
5-5 High Voltage Diode
5-6 Main Relay and Power Control Relay
5-7 Adjustment of Primary Switch, Door Sensing Switch and Monitor Switch
5-2
1. Check continuity of the capacitor with the meter set at the highest resistance scale.
2. Once the capacitor is charged, a normal capacitor shows continuity for a short time, and then indicates 9MΩ.
3. A shorted capacitor will show continuous continuity.
4. An open capacitor will show constant 9MΩ.
5. Resistance between each terminal and chassis should read infinite.
1. Isolate the diode from the circuit by disconnecting its leads.
2. With the ohm-meter set at the highest resistance scale, measure across the diode terminals. Reverse the
meter leads and read the resistance. A meter with 6V, 9V or higher voltage batteries should be used to
check the front-to back resistance of the diode (otherwise an infinite resistance may be read in both
directions). The resistance of a normal diode will be infinite in one direction and several hundred KΩin
the other direction.
1. When mounting Primary switch and Interlock
Monitor switch to Latch Body, consult the
figure.
2. No specific adjustment during installation of
Primary switch and Monitor switch to the latch
body is necessary.
3. When mounting the Latch Body to the oven
assembly, adjust the Latch Body by moving it so
that the oven door will not have any play in it.
Check for play in the door by pulling the door
assembly. Make sure that the latch keys move
smoothly after adjustment is completed.
Completely tighten the screws holding the Latch
Body to the oven assembly.
4. Reconnect to Monitor switch and check the
continuity of the monitor circuit and all latch
switches again by following the components test
procedures.
5. Confirm that the gap between the switch
housing and the switch actuator is no more than
0.5mm when door is closed.
1. The relays are located on the PCB Ass'y. Isolate them from the main circuit by disconnecting the leads.
2. Operate the microwave oven with a water load in the oven. Set the power level set to high.
3. Check continuity between terminals of the relays after the start pad is pressed.
Precaution
For continued protection against radiation hazard, replace parts in accordance with the wiring diagram and be sure to use the
correct part number for the following switches: Primary interlock and door sensing switches, and the interlock monitor switch
(replace all together). Then follow the adjustment procedures below. After repair and adjustment, be sure to check the continuity
of all interlock switches and the interlock monitor switch.
Alignment and Adjustments
Door Open Door Closed
Primary switch ∞0
Monitor switch (COM-NC) 0 ∞
Door Sensing S/W ∞0
Primary Interlock Switch
Lever Door
Body Latch Door Sensing
Switch
Interlock Monitor
Switch

Samsung Electronics 5-3
The output power of the magnetron can be measured by performing a water temperature rise test.
Equipment needed :
* Two 1-liter cylindrical borosilicate glass vessel (Outside diameter 190 mm)
* One glass thermometer with mercury column
NOTE: Check line voltage under load. Low voltage will lower the magnetron output. Make all temperature
and time tests with accurate equipment.
1. Fill the one liter glass vessel with water.
2. Stir water in glass vessel with thermometer, and record glass vessel's temperature ("T1", 10±0.2˚C).
3. After moving the water into another glass vessel, place it in the center of the cooking tray. Set the oven to high
power and operate for 43 seconds exactly. (1 seconds included as a holding time of magnetron oscillation:)
4. When heating is finished, stir the water again with the thermometer and measure the temperature ("T2").
5. Subtract T1from T2. This will give you the water temperature rise. (∆T)
6. The output power is obtained by the following formula;
7. Normal temperature rise for this model is 9.9˚C to 10.5˚C at 'HIGH'.
NOTE 1: Variations or errors in the test procedure will cause a variance in the temperature rise.
Additional power test should be made if temperature rise is marginal.
NOTE 2: Output power in watts is computed by multiplying the temperature rise (step 5) by a factor of 91
times the of centigrade temperature.
4.187 x 1000 x ∆T+0.88xMcx(T2-T0)
Output Power = 41.87
41.87: Heating Time (sec)
4.187 : Coefficient for Water
1000 : Water (cc)
∆T : Temperature Rise (T2-T1)
Mc : Cylindrical borosilicate glass weight
To : Room temperature.
5-8 Output Power of Magnetron
Alignment and Adjustments
CAUTION
MICROWAVE RADIATION
PERSONNEL SHOULD NOT ALLOW EXPOSURE TO MICROWAVE RADIATION FROM MICROWAVE GENERATOR OR OTHER PARTS
CONDUCTING MICROWAVE ENERGY.
5-9 Microwave Heat Distribution - Heat Evenness
The microwave heat distribution can be checked indirectly by measuring the water temperature rise at
certain positions in the oven:
1. Prepare five beakers made of 'Pyrex', having 100 milliliters capacity each.
2. Measure exactly 100milliliters off water load with a measuring cylinder, and pour into each beaker.
3. Measure the temperature of each water load. (Readings shall be taken to the first place of decimals.)
4. Put each beaker in place on the cooking tray as illustrated in figure below. Start heating.
5. After heating for 2 minutes, measure the water temperature in each beaker.
6. Microwave heat distribution rate can be calculated as follows:
Minimum
Temperature Rise
Heat Distribution = X 100(%)
Maximum
Temperature Rise
The result should exceed 80%.
D
D
D/4
D/4
D/4
D/4
Cooking Tray
Beaker

5-4 Samsung Electronics
1) Pour 275±15cc of 20±5˚C(68±9˚F) water in a beaker
which is graduated to 600cc, and place the beaker in
the center of the oven.
2) Start to operate the oven and measure the leakage by
using a microwave energy survey meter.
3) Set survey meter with dual ranges to 2,450MHz.
4) When measuring the leakage, always use the 2 inch
spacer cone with the probe. Hold the probe
perpendicular to the cabinet door. Place the spacer
cone of the probe on the door and/or cabinet door
seam and move along the seam, the door viewing
window and the exhaust openings moving the probe
in a clockwise direction at a rate of 1 inch/sec. If the
leakage testing of the cabinet door seam is taken near a corner of the door, keep the probe perpendicular to
the areas making sure that the probe end at the base of the cone does not get closer than 2 inches to any
metal. If it gets closer than 2 inches, erroneous readings may result.
5) Measured leakage must be less than 4mW/cm2, after repair or adjustment.
Alignment and Adjustments
5-13 Leakage Measuring Procedure
5-10 Procedure for Measurement of Microwave Energy Leakage
5-12 Note on Measurement
5-11 Check for Microwave Leakage
5-13-1 Record keeping and notification after measurement
1) After adjustment and repair of a radiarion preventing device, make a repair record for the measured
values, and keep the data.
2) If the radiation leakage is more than 4 mW/cm2after determining that all parts are in good condition,
functioning properly and the identical parts are replaced as listed in this manual notift that fact to ;
CENTRAL SERVICE CENTER
5-13-2 At least once a year have the microwave energy survey meter checked for accuracy by its
manufacturer.
1. Remove the outer panel.
2. Pour 275±15cc of 20±5˚C(68±9˚F) water in a beaker which is
graduated to 600cc, and place the beaker in the center of the oven.
3. Start the oven at the highest power level.
4. Set survey meter dual ranges to 2,450MHz.
5. Using the survey meter and spacer cone as described above,
measure arnear the opening of magnetron, the surface of the air
guide and the surface of the wave guide as shown in the following
photo.( but avoid the high voltage components.) The neading
should be less than 4mW/cm2.
1) Do not exceed the limited scale.
2) The test probe must be held on the grip of the handle, otherwise a false reading may result when the
operator's hand is between the handle and the probe.
3) When high leakage is suspected, do not move the probe horizontally along the oven surface; this may
cause damage to the probe.
4) Follow the recommendation of the manufacturer of the microwave energy survey meter.
Maximum allowable leakage is 5mW/cm2.
4mW/cm2is used to allow for measurement and meter accuracy

Samsung Electronics
6. Troubleshooting
6-1
PRECAUTION
1. CHECK GROUNDING BEFORE CHECKING FOR TROUBLE.
2. BE CAREFUL OF THE HIGH VOLTAGE CIRCUIT.
3. DISCHARGE THE HIGH VOLTAGE CAPACITOR.
4. WHEN CHECKING THE CONTINUITY OF THE SWITCHES OR TRANSFORMER, DISCONNECT ONE LEAD WIRE FROM THESE
PARTS AND THEN CHECK CONTINUITY WITHOUT THE POWER SOURCE ON. TO DO OTHERWISE MAY RESULT IN A FALSE
READING OR DAMAGE TO YOUR METER.
5. DO NOT TOUCH ANY PART OF THE CIRCUIT OR THE CONTROL CIRCUIT BOARD, SINCE STATIC DISCHARGE MAY DAMAGE IT.
ALWAYS TOUCH GROUND WHILE WORKING ON IT TO DISCHARGE ANY STATIC CHARGE BUILT UP.
6-1 Electrical Malfunction
SYMPTOM CAUSE CORRECTIONS
Oven is dead. 1. Open or loose lead wire harness Check fan motor when thermal cutout is defective.
Fuse is OK. 2. Open thermal cutout (Magnetron)
No display and no operation at all. 3. Open low voltage transformer Check Ass'y PCB when LVT is defective.
4. Defective Ass'y PCB
No display and no operation at all. 1. Shorted lead wire harness Check adjustment of primary, interlock monitor,
Fuse is blown. 2. Defective primary latch switch (NOTE 1) power relay, door sensing switch.
3. Defective monitor switch (NOTE1)
4. Shorted HVCapacitor
5. Shorted HVTransformer (NOTE2)
NOTE 1: All of these switches must be replaced at the same time.
(refer to adjustment instructions)
Check continuity of power relay contacts and if it has continuity, replace power
relay also.
NOTE 2: When HVTransformer is replaced, check diode and magnetron also.
Oven does not accept 1. Key input is not in-Sequence Refer to operation procedure.
key input (Program) 2. Open or loose connection of membrane
key pad to Ass'y PCB
3. Shorted or open membrane panel
4. Defective Ass'y PCB Replace PCB main.
1. Off-alignment of latch switches Adjust door and latch switches.
2. Open or loose connection of high voltage
circuit especially magnetron filament
circuit
NOTE: Large contact resistance will bring
lower magnetron filament voltage and
Timer starts countdown but no cause magnetron to lower output and/or
microwave oscillation. intermittent oscillation.
(No heat while oven lamp and 3. Defective high voltage components Check high voltage component according to
fan motor turn on.) H.V.Transformer component test procedure and replace if it is
H.V.Capacitor defective.
H.V.Diode
Magnetron
4. Open or loose wiring of power relay
5. Defective primary latch switch
6. Defective power relay or Ass'y PCB Replace PCB main.

Samsung Electronics6-2
Troubleshooting
SYMPTOM CAUSE CORRECTIONS
Oven lamp and fan motor turn on 1. Misadjustment or loose wiring Adjust door and latch switches.
of primary latch switch
2. Defective primary latch switch
Oven can program but timer 1. Open or loose wiring of secondary Adjust door and interlock switches.
does not start. interlock switch
2. Off-alignment of primary interlock
3. Defective secondary interlock S/W
Microwave output is low;. 1. Decrease in power source voltage. Consult electrician.
Oven takes longer time to 2. Open or loose wiring of magnetron
cook food. filament circuit. (Intermittent oscillation))
3. Aging of magnetron
Fan motor turns on when plugged in Loose wiring of door sensing switch Check wire of door sensing switch.
Oven does not operate and return Defective Ass'y PCB Replace PCB main.
to the plugged in mode.
Loud buzzing noise can be heard. 1. Loose fan and fan motor Tighten screws of fan motor.
2. Loose screws on H.V.Transformer Tighten screws of H.V.Transformer.
3. Shorted H.V.Diode Replace H.V.Diode.
Turntable motor does not rotate. 1. Open or loose wiring of turntable motor. Check the wire of turntable motor.
2. Defective turntable motor. Replace turntable motor.
Oven stops operation during cooking 1. Open or loose wiring of primary Adjust door and latch switches.
interlock switch
2. Operation of thermal cutout(Magnetron)
Sparks 1. Metallic ware or cooking dishes Inform the customer.
touching on the oven wall.
2. Ceramic ware trimmed with gold or Do not use any type of cookware with
silver powder also causes sparks. metallic trimming.
Uneven cooking Uneven intensity of microwave due to Wrap thinner parts of the food with
its characteristics. aluminum foil.
Use plastic wrap or cover with a lid.
Stir once or twice while cooking
foods such as soup, cocoa, or milk.
Noise from the turntable motor Noise may result from the motor. Replace turntable motor.
when it starts to operate.
6-1 Electrical Malfunction(continued)

Samsung Electronics
6. Troubleshooting
6-1
PRECAUTION
1. CHECK GROUNDING BEFORE CHECKING FOR TROUBLE.
2. BE CAREFUL OF THE HIGH VOLTAGE CIRCUIT.
3. DISCHARGE THE HIGH VOLTAGE CAPACITOR.
4. WHEN CHECKING THE CONTINUITY OF THE SWITCHES OR TRANSFORMER, DISCONNECT ONE LEAD WIRE FROM THESE
PARTS AND THEN CHECK CONTINUITY WITHOUT THE POWER SOURCE ON. TO DO OTHERWISE MAY RESULT IN A FALSE
READING OR DAMAGE TO YOUR METER.
5. DO NOT TOUCH ANY PART OF THE CIRCUIT OR THE CONTROL CIRCUIT BOARD, SINCE STATIC DISCHARGE MAY DAMAGE IT.
ALWAYS TOUCH GROUND WHILE WORKING ON IT TO DISCHARGE ANY STATIC CHARGE BUILT UP.
6-1 Electrical Malfunction
SYMPTOM CAUSE CORRECTIONS
Oven is dead. 1. Open or loose lead wire harness Check fan motor when thermal cutout is defective.
Fuse is OK. 2. Open thermal cutout (Magnetron)
No display and no operation at all. 3. Open low voltage transformer Check Ass'y PCB when LVT is defective.
4. Defective Ass'y PCB
No display and no operation at all. 1. Shorted lead wire harness Check adjustment of primary, interlock monitor,
Fuse is blown. 2. Defective primary latch switch (NOTE 1) power relay, door sensing switch.
3. Defective monitor switch (NOTE1)
4. Shorted HVCapacitor
5. Shorted HVTransformer (NOTE2)
NOTE 1: All of these switches must be replaced at the same time.
(refer to adjustment instructions)
Check continuity of power relay contacts and if it has continuity, replace power
relay also.
NOTE 2: When HVTransformer is replaced, check diode and magnetron also.
Oven does not accept 1. Key input is not in-Sequence Refer to operation procedure.
key input (Program) 2. Open or loose connection of membrane
key pad to Ass'y PCB
3. Shorted or open membrane panel
4. Defective Ass'y PCB Replace PCB main.
1. Off-alignment of latch switches Adjust door and latch switches.
2. Open or loose connection of high voltage
circuit especially magnetron filament
circuit
NOTE: Large contact resistance will bring
lower magnetron filament voltage and
Timer starts countdown but no cause magnetron to lower output and/or
microwave oscillation. intermittent oscillation.
(No heat while oven lamp and 3. Defective high voltage components Check high voltage component according to
fan motor turn on.) H.V.Transformer component test procedure and replace if it is
H.V.Capacitor defective.
H.V.Diode
Magnetron
4. Open or loose wiring of power relay
5. Defective primary latch switch
6. Defective power relay or Ass'y PCB Replace PCB main.

Samsung Electronics6-2
Troubleshooting
SYMPTOM CAUSE CORRECTIONS
Oven lamp and fan motor turn on 1. Misadjustment or loose wiring Adjust door and latch switches.
of primary latch switch
2. Defective primary latch switch
Oven can program but timer 1. Open or loose wiring of secondary Adjust door and interlock switches.
does not start. interlock switch
2. Off-alignment of primary interlock
3. Defective secondary interlock S/W
Microwave output is low;. 1. Decrease in power source voltage. Consult electrician.
Oven takes longer time to 2. Open or loose wiring of magnetron
cook food. filament circuit. (Intermittent oscillation))
3. Aging of magnetron
Fan motor turns on when plugged in Loose wiring of door sensing switch Check wire of door sensing switch.
Oven does not operate and return Defective Ass'y PCB Replace PCB main.
to the plugged in mode.
Loud buzzing noise can be heard. 1. Loose fan and fan motor Tighten screws of fan motor.
2. Loose screws on H.V.Transformer Tighten screws of H.V.Transformer.
3. Shorted H.V.Diode Replace H.V.Diode.
Turntable motor does not rotate. 1. Open or loose wiring of turntable motor. Check the wire of turntable motor.
2. Defective turntable motor. Replace turntable motor.
Oven stops operation during cooking 1. Open or loose wiring of primary Adjust door and latch switches.
interlock switch
2. Operation of thermal cutout(Magnetron)
Sparks 1. Metallic ware or cooking dishes Inform the customer.
touching on the oven wall.
2. Ceramic ware trimmed with gold or Do not use any type of cookware with
silver powder also causes sparks. metallic trimming.
Uneven cooking Uneven intensity of microwave due to Wrap thinner parts of the food with
its characteristics. aluminum foil.
Use plastic wrap or cover with a lid.
Stir once or twice while cooking
foods such as soup, cocoa, or milk.
Noise from the turntable motor Noise may result from the motor. Replace turntable motor.
when it starts to operate.
6-1 Electrical Malfunction(continued)

Samsung Electronics
7. Exploded Views and Parts List
7-1 Exploded Views
7-1
M1
M27
M29
M36
C1
C2
C3
C4
C5 C6
C7
M35
M18
M21
M23
M19
M37
M38
M39
M25
M26
M2
M33
M5
M28
M34
M6
M9
M10
M13
M15
M16
M17
B1
B2
B2
B4
B3
M7
M8
M12
M41
D1
D10
D2
D3
D5
D6
D9
D4
D7
D8
M40
M24
M20
M14
M11
M22
M31
M30
M3
M32
M4
M42
M43
M44
M45
M46
M47

7-2 Main Parts List
7-2 Samsung Electronics
Exploded Views and Parts List
Ref. No. Parts No. Description Specification Q'ty Remark
M 1 DE70-30002A PANEL-OUTER SECC,T0.6,W424.7,L1155,EXOPY-C 1
M 2 DE63-90035H CUSHION-RUBBER DFA20,T2,W190,L200,BLK 1
M 3 DE61-30006A SUPPORTER-HEATER ALUMINA,5G,2ND-W/P 1
M 4 DE61-70060A SPRING-PLATE SK-5,T0.5 1
M 5 3601-000440 FUSE-FERRULE 250V,20A,TL,CERAMIC,6.35x31.8m 1
M 6 DE91-40101A ASSY NOISE FILTER SN-U20A,250V,20A,SECA 1
M 7 DE31-10157A MOTOR-FAN SMF-657UC,120/60,2600,MB6774W 1
M 8 DE39-20037G ASSY POWER CORD KKP-30B,120V60HZ,1150,GRY 1
M 9 DE39-40735A WIRE HARNESS-A 120V60Hz,MG7980W/XAP,SEPA 1
M10 DE47-20009A THERMOSTAT PW2N-520PB,160/60,250V/7.5A,H 1
M11 DE61-50490A BRACKET-TCO SECC1,T0.6,34,58 1
M12 DE65-20014A CABLE CLAMP DA-6N,NY-66 1 P-CORD
M13 OM75PH(31)ESS ASSY-MAGNETRON OM75PH(31)ESS 1
M14 DE63-90065N CUSHION-GUIDE PUT-FOAM,T10,W10,L200,BLK,MW55 1 CV/AIR
M15 4713-001012 LAMP-INCANDESCENT 130V,-,40W,ORG,B/L,-,25X71 1
M16 DE71-60016A COVER-AIR PP,2,WHT,M945/M245 1
M17 DE93-20001A ASSY BODY LATCH 2ND-W1,M97G45/M9745 1
M18 DE66-90013A LEVER-DOOR POM(F20-01),NTR,MW5630T 1
M19 DE26-10115B TRANS-H.V SHV-6574UC1-1,120V,2260V/3.42V,60HZ,UL923 1
M20 DE63-90168A CUSHION-HVT NEOPRENE-RUBBER,T28,W22,L50,BL 1
M21 DE61-50106A BRACKET-HVC SECC,T0.8,W31,L125.8 1
M22 2501-001106 C-OIL 910nF,2.1KV,BK,54x35x75,20mm 1
M23 DE59-40001A DIODE-H.V HVR-1X-32B-12 1
M24 DE65-20025A CABLE CLAMP DAWS-2NB,NYLON66,NTR,WIRE,SADD 1
M25 DE61-40066A FOOT PP,BLK,-,-,3RD-W 2
M26 DE80-10002A BASE-PLATE SGCC,T(0.8),W(404),L(633),MW65 1
M27 DE31-10154A MOTOR-DRIVE M2HJ49ZR02,ST-16,50/60HZ 1
M28 DE47-20173A THERMOSTAT PW-2N(90/60)30,187Y,250V7.5A,9 1 CV-TCO
M29 DE71-60380A COVER-CEILING MICA-SHEET,T0.5,W60,L121 1
M30 DE47-20011A THERMOSTAT PW-2N(115/93)187Y,250V7.5A,115 1
M31 DE72-60005C GUIDE-AIR SECC,T0.5,W210,L225,CE245G 1
M32 DE63-90005A SPONGE T4,W10,L1000 1
M33 DE61-50403C BRACKET-UPPER SECC+H3PO4Na,T0.6,W293.3,L383 1
M34 DE39-40409A WIRE HARNESS-E 230V50HZ,M9G45,CTW 1
M35 DE92-40171G ASSY DOOR P/BUTTON,P/WHT,MG7980W/XAP 1
M36 DE93-30534F ASSY CONTROL-BOX MG7980W/XAP 1
M37 DE74-20002B TRAY-COOKING GLASS,T6,PI360,1.2CUFT,HKG 1
M38 DE92-90189J ASSY-GUIDE ROLLER D16.5,STD,SPS 1
M39 DE67-60002A COUPLER PPS,5GR,BRN,M97G45 1
M40 DE92-90019A ASSY-RACK WIRE RE-751 1
M41 DE71-60355B COVER-BACK SECC,T0.6,W265,L368,CE245GB 1
M42 DE47-70031D HEATER-GRILL D6.8,120V,1300W,10.8OHM,M9G45( 1
M43 DE63-20017A GASKET-HEATER BRASS,T1.5,OD30.5,ID22.5 1
M44 DE60-40009B WASHER-TEFLON SLOT,ID22.2,OD28,T1.2,TEFLON 1
M45 DE61-50021A BRACKET-FLANGE SECC1,T0.8,32,32 1
M46 DE61-50025A BRACKET-EARTH BSS2-A,T1.0,CE745G 1
M47 DE61-50027B BRACKET-HEATER SECC,T1.0,W51,L55,CE945GF 1
: Option Parts : Warning : Electrostatically Sensitive Devices

Samsung Electronics 7-3
7-3 Door Parts List
Ref. No. Parts No. Description Specification Q'ty Remarks
D 1 DE67-20005A SCREEN-DOOR ACRYL/PC,T(1.5),W(212.5),L(440 1
D 2 DE64-40006A DOOR-KEY POM(TC3005),T2.0,12GR,BLK,CE94 1
D 3 DE61-70128A SPRING-KEY HSW3,PI0.6,D5,BLUING 1
D 4 DE64-40009A DOOR-A ABS(HR0370U),T2.5,IDEOMW6574W 1
D 5 DE92-50128F ASSY DOOR-E COATING,BLK,MW6575G 1
D 6 DE64-40010B DOOR-C PP(TB53),T1.5,BLK,1.2CU.FT,M24 1
D 7 DE01-00004B FILM-DOOR ACRYL+SILICON,T0.15,W183,L325 1
D 8 DE61-80002A HINGE-UPPER SCP1,T2.3,26,77,ZPC3,WHT,CE945 1
D 9 DE61-80003A HINGE-LOWER SCP1,T2.3,26,77,ZPC3,WHT,CE945 1
D10 DE02-00125A TAPE-DOUBLE FACE ACRYL,T0.45,W9,WHT,WF103,#4420 1
7-4 Control Parts List
Ref. No. Parts No. Description Specification Q'ty Remarks
C 1 DE66-20006A BUTTON-PUSH RESIN-ABS(HR-0370U),P/WHT,M945 1
C 2 DE61-70076A SPRING-BUTTON HSWR,PI0.6 1
C 3 DE34-10206Y SWITCH-MEMBRANE PE-SHEET,W89.7,L199.8,MG7980W, 1
C 4 DE72-70005A CONTROL-PANEL ABS(VH0853),164G,PURE-WHT,T2.5 1
C 5 DE67-40002A WINDOW-DISPLAY RESIN-ACRYLIC,T2.3,M945(IDEO), 1
C 6 RA-USA2ND-31 ASSY PCB PARTS MG7980W(SEPW),AC120V60Hz 1
C 7 DE93-30404E ASSY CONTROL-PANEL MW6574W 1
7-5 Body Latch Parts List
Ref. No. Parts No. Description Specification Q'ty Remarks
B 1 DE66-40001A LATCH-BODY POM(F20-02),40GR,NTR,-,-,- 1
B 2 3405-000178 SWITCH-MICRO 250V,15A,200gf,SPST-NO 2
B 3 3405-000175 SWITCH-MICRO 250V,15A,200gf,SPST-NO 1
B 4 DE66-90001A LEVER-SWITCH P.O.M(F20-02),2,6,NTR,2ND-W-P/ 1
Exploded Views and Parts List