LG MC-7682W Service Manual

Page 1
CAUTIONS
• Be sure to check microwave leakage prior to servicing the oven if the oven is operative prior to servicing.
• The service personnel should inform the manufacture importer, or assembler of any certified oven unit found to have a microwave emission level in excess of 5 mW/cm2and should
repair any unit found to have excessive emission levels at no cost to the owner and should ascertain the cause of the excessive leakage. The service personnel should instruct the owner not to use the unit until the oven has been brought into compliance.
• If the oven operates with the door open, the service personnel should:
- Tell the user not to operate the oven.
- Contact the manufacturer.
• The service personnel should check all surface and vent openings for microwave leakage.
• Check for microwave leakage after every servicing. The power density of the microwave radiation leakage emitted by the microwave oven should not exceed 4 mW/cm2. Always start measuring of an unknown field to assure safety for operating personnel from radiation leakage.
MEASURING MICROWAVE ENERGY LEAKAGE
• Pour 275±15cc of 20±5°C(68±9°F) water in a beaker which is graduated to 600 cc, and place the beaker on the center of the turntable.
• Set the energy leakage monitor to 2,450 MHz and use it following the manufacturer's recommended test procedure to assure correct result.
• When measuring the leakage, always use the 2­inch (5cm) spacer supplied with the probe.
• Operate the oven at its maximum output.
• Measure the microwave radiation using and electromagnetic radiation monitor by holding the probe perpendicular to the surface being measured
Move probe along shaded area
Probe scanning speed Less than 2.5 cm/sec ( 1in/sec)
5-1
SERVICE INFORMATION
TOOLS AND MEASURING INSTRUMENTS
MICROWAVE LEAKAGE TEST
NECESSARY TOOLS
Tools normally used for TV servicing are sufficient. Standard tools are listed below.
• Diagonal pliers
• Long nose pliers
• Phillips screwdriver
• Flat blade screwdriver
• Wrench (size 5mm)
• Nutdriver (size 5mm)
• Adjustable wrench
• Soldering iron
• Solder
• Vinyl insulation tape
• Polishing cloth
NECESSARY MEASURING INSTRUMENTS
• TESTER(VOLTS-DC, AC., Ohmmeter)
• Microwave survey meter
- Holaday HI-1500 HI-1501
- Narda 8100
8200
• Inch scale
• 600 cc non conductive material beaker (glass or plastic), inside diameter: approx. 8.5 cm(3
1
/2
in.)
• Cylindrical and made of borosilicate glass vessel. max. thickness: 3 mm outside diameter: approx. 190mm height: approx. 90mm
• Glass thermometer: 100°C or 212°F (1 deg scale)
Page 2
MEASUREMENT WITH OUTER CASE REMOVED
• When you replace the magnetron, measure for microwave energy leakage before the outer case is installed and after all necessary components are replaced or adjusted.
Special care should be taken in measuring the
following parts. (Circled area of below Fig.)
- Around the magnetron
- The waveguide
MEASUREMENT WITH A FULLY ASSEMBLED OVEN
• After all components, including the outer case, are fully assembled, measure for microwave energy leakage around the door viewing window, the exhaust opening, and air inlet openings.
• Microwave energy leakage must not exceed the values prescribed below.
NOTE: Leakage with the outer case removed less than
5 mW/cm.sq. Leakage for a fully assembled oven (Before the latch switch (primary) is interrupted) with the door in a slightly opened position-less than 2 mW/cm.sq.
NOTES WHEN MEASURING
• Do not exceed meter full scale deflection.
• The test probe must be removed no faster than 1 inch/sec (2.5 cm/sec) along the shaded area, otherwise a false reading may result.
• The test probe must be held with the grip portion of the handle.
A false reading may result if the operator's hand is
between the handle and the probe.
• When testing near a corner of the door, keep the probe perpendicular to the surface making sure the probe horizontally along the oven surface, this may possibly cause probe damage.
RECORD KEEPING AND NOTIFICATION AFTER MEASUREMENT
• After adjustment and repair of any microwave energy interruption or microwave energy blocking device, record the measured values for future reference. Also enter the information on the service invoice.
• The microwave energy leakage should not be more than 4 mW/cm.sq. after determining that all parts are in good condition, functioning properly and genuine replacement parts which are listed in this manual have been used.
• At least once a year, have the electromagnetic energy leakage monitor checked for calibration by its manufacturer.
WARNING : AVOID CONTACTING ANY
HIGH VOLTAGE PARTS
5-2
Page 3
• Microwave power output measurement is made with the microwave oven supplied at its rated voltage and operated at its maximum microwave power setting with a load of (1000 ± 5)g potable water.
• 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.
• The oven and the empty vessel are at ambient temperature prior to the start of the test.
• The initial temperature (±1) of the water is (10±2)°C. 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 position and the microwave power switched on.
• The time T for the temperature of the water to rise by a value T of (10±2)°K is measured, where T is the time in seconds and T is the temperature rise. The initial and final water temperatures are selected so that the maximum difference between the final water temperature and the ambient temperature is 5°K.
• The microwave power output P in watts is calculated from the following formula:
P =
is measured while the microwave generator is operating at full power. Magnetron filament heat-up time is not included.
• The water is stirred, to equalize temperature throughout the vessel, prior to measuring the final water temperature.
•Stirring devices and measuring instruments are
selected in order to minimize addition or removal of heat.
WATER LOAD
TURNTABLE
MEASUREMENT OF MICROWAVE POWER OUTPUT
DISASSEMBLY AND ADJUSTMENT
A. OUTER CASE REMOVAL
1) Disconnect the power supply cord from the outlet.
2) Remove the screws from the rear and along side edges of the case.
The outer case must be moved backward to be lifted
off.
B. POWER SUPPLY CORD REMOVAL
1) Remove the outer case.
2) Disconnect two terminals, and remove one screw of
the earth terminal.
CAUTION: DISCHARGE THE HIGH VOLTAGE
CAPACITOR BEFORE SERVICING
(refer to page 2-1)
C. CONTROLLER ASSEMBLY REMOVAL
1) Disconnect the leadwire from the PCB SUB ASS’Y.
2) Remove the screws for the earth and securing the control panel.
3) Lift control panel ASS’Y from the oven by the tab
unhooked.
5-3
4187 X (T) + 0.88 X (T2 - T0) X M
T
• T2: Temperature after heating
• T0: Temperature of bowl
• M: Weight of bowl
Page 4
D. DOOR GROSS ASSEMBLY REMOVAL
1) Open the door.
2) Remove the choke cover very carefully with a flat­blade screwdriver.
CAUTION : Be careful not to damage door seal plate
by screwdriver.
3) Lift up and push the door.
NOTE:
1. After replacing the door, be sure to check that the
primary switch, monitor switch, and secondary switch operate normally.
2. After replacing the door, check for microwave energy
leakage with a survey meter. Microwave energy must be below the limit of 5 mW/cm. (with a 275 ml water load)
3. When mounting the door assembly to the oven
assembly, be sure to adjust the door assembly parallel to the chassis. Also adjust so the door has no play between the inner door surface and oven frame assembly. If the door assembly is not mounted properly, microwaves may leak from the clearance between the door and the oven.
E. HIGH VOLTAGE TRANSFORMER
REMOVAL
1) Discharge the high voltage capacitor.
2) Disconnect the leadwire from magnetron, high voltage
transformer, and capacitor.
3) Remove the screw holding the high voltage
transformer to the baseplate.
F. AIR DUCT ASSEMBLY REMOVAL
1) Disconnect the leadwire from lamp and MGT thermostat.
2) Remove the mounting screw to the magnetron.
G. MAGNETRON REMOVAL
1) Disconnect the leadwire from the high voltage transformer and high voltage capacitor.
2) Carefully remove the mounting screws holding the magnetron and the waveguide.
3) Remove the magnetron ASS’Y until the tube is clear from the waveguide.
NOTE:
1. When removing the magnetron, make sure its dome does not hit any adjacent parts, or it may be damaged.
2. When replacing the magnetron, be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition.
3. After replacing the magnetron, check for microwave leakage with a survey meter around the magnetron. Microwave energy must be below the
limit of 5 mW/cm2. (With a 275 ml. water load).
Make sure that gasket is rigidly attached to the
magnetron. To prevent microwave leakage,
tighten the mounting screws properly, making sure there is no gap between the waveguide and the magnetron.
5-4
Magnetron
Air Duct
Page 5
5-5
H. FAN MOTOR ASSEMBLY REMOVAL
1) Discharge the high voltage capacitor.
2) Disconnect the leadwire from fan motor, noise filter and high voltage capacitor.
3) Remove the two screws holding the the suction guide ASS’Y to the oven cavity and remove the high voltage diode earth screw.
4) Remove the screw of the capacitor bracket.
5) Remove the two screws holding the fan motor ASS’Y to the suction guide ASS’Y.
I. HIGH VOLTAGE CAPACITOR AND
DIODE REMOVAL
1) Discharge the high voltage capacitor.
2) Disconnect the leadwire from fan motor, noise filter and high voltage capacitor.
3) Remove the screw holding the suction guide ASS’Y to the oven cavity and remove the high voltage diode earth screw.
4) Remove the screw holding the high voltage capacitor bracket.
J. THE TURNTABLE MOTOR REMOVAL
1) Remove the turntable.
2) Remove the turntable shaft VERY CAREFULLY with a slotted screwdriver.
3) Lay the unit down on its back.
4) Remove the turntable motor cover.
The turntable base cover is easily removed by
pinching the six parts with a wire cutting.
5) Disconnect the leadwire from the turntable motor terminals.
6) Remove the screw securing the turntable motor to the oven cavity ASS’Y
7) After repairing the motor, rotate the removed turntable motor cover.
8) Fit the turntable motor cover’s projecting part to the base plate slit.
NOTE:
1. Remove the wire lead from the turntable motor VERY CAREFULLY.
2. Be sure to grasp the connector, not the wires, when removing.
Wire Leads
Turntable Motor
H.V. Transformer
Fan Motor ASS'Y
Suction Guide
H.V. Capacitor
Page 6
K. C-MOTOR, THERMISTOR AND
SHEATH HEATER REMOVAL
1) Remove the two screws securing the cover assembly to the oven cavity.
2) Disconnect the leadwire from the circulation motor terminal and the sheath heater.
3) Remove the screws of the thermistor, guide assy­chamber and lift up the guide assy-chamber.
4) Remove a hex nut securing the circulation fan to shaft of the C-motor.
5) Remove screws securing the motor bracket to the guide assy-chamber.
6) Remove two hex nuts securing the C-motor to the motor bracket.
L. PCB ASSEMBLY REMOVAL
1) Remove the control panel assembly from the
cavity. (Refer to control panel assembly removal on previous page.)
2) Remove screws which hold the PCB SUB ASS’Y to
the control panel.
3) Take off the PCB SUB ASS’Y from the control
panel.
M. INTERLOCK SYSTEM
1) INTERLOCK MECHANISM The door lock mechanism is a device which has
been specially designed to eliminate completely microwave activity when the door is opened during cooking and thus to prevent the danger resulting from the microwave leakage.
2)
MOUNTING OF THE PRIMARY/MONITOR/
SECONDARY SWITCHES TO THE LATCH BOARD
3) INSTALLATION AND ADJUSTMENT OF THE LATCH BOARD TO THE OVEN ASSEMBLY
• Mount the latch board to the oven assembly.
• Adjust the latch board in the arrow direction so that
oven door will not have any play in it when the door is closed.
• Tighten the mounting screw.
5-6
Latch Board
Primary Interlock Switch
Interlock Monitor Switch
Secondary Interlock Switch
Page 7
A. PRIMARY INTERLOCK SWITCH TEST
When the door release button is depressed slowly with the door closed, an audible click should be heard at the same time or successively at intervals. When the button is released slowly, the latches should activate the switches with an audible click. If the latches do not activate the switches when the door is closed, the switches should be a adjusted in accordance with the adjustment procedure. Disconnect the wire lead from the primary switch. Connect the ohmmeter leads to the common (COM) and normally open (NO) terminal of the switch. The meter should indicate an open circuit in the door open condition. When the door is closed, the meter should indicate a closed circuit. When the primary switch operation is abnormal, make the necessary adjustment or replace the switch only with the same type of switch.
B. SECONDARY INTERLOCK SWITCH TEST
Disconnect the wire lead from the secondary switch. Connect the ohmmeter leads to the common (COM) and normally open (NO) terminals of the switch. The meter should indicate a open circuit in the door open condition. When the door is closed, meter should indicate an closed circuit. When the secondary switch operation is abnormal, make the necessary adjustment or replace the switch only with the same type of switch.
C. MONITOR SWITCH TEST
Disconnect the wire lead from the monitor switch. Connect the ohmmeter leads to the common (COM) and normally closed (NC) terminals of the switch. The meter should indicate closed circuit in the door open condition. When the door is closed, meter should indicate an open circuit. When the monitor switch operation is abnormal, replace with the same type of switch.
NOTE: After repairing the door or the interlock system, it is necessary to do this continuity test before operating the oven.
5-7
WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION
EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS.
TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR PRIMARY SWITCH TYPE NO. SZM-V 16-FA-61 OR VP-531A-OF FOR MONITOR SWITCH TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR SECONDARY SWITCH
INTERLOCK CONTINUITY TEST
COMPONENTS TEST PROCEDURE RESULTS
SWITCHES Check for continuity of the switch (Wire leads removed) with a Multi-meter
Primary Switch
Monitor Switch
Secondary Switch
NOTE: After checking for the continuity of switches, make sure that are
correctly connected.
Door open
Door
close
COM
NO
COM
NC
COM
NO
Page 8
5-8
CAUTIONS
1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE OUTER CASE FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER OF WATER IN CONTAINER) IN THE OVEN.
COMPONENTS TEST PROCEDURE RESULTS
HIGH VOLTAGE TRANSFORMER (Wire leads removed)
MAGNETRON (Wire leads removed)
1. Measure the resistance. (Ohm-meter scale: Rx1 and Rx100)
• Primary winding
• Secondary winding
• Filament winding
2. Measure the resistance. (Ohm-meter scale: Rx1000)
• Primary winding to ground
• Filament winding to ground
1. Measure the resistance. (Ohm-meter scale: Rx1)
• Filament terminal
2. Measure the resistance. (Ohm-meter scale: Rx1000)
• Filament to chassis
Approx.: 1.9 ohm Approx.: 90 ohm Less than: 1 ohm
Normal: Infinite Normal: Infinite
Normal: Less than 1 ohm
Normal: Infinite
FILAMENT WINDING TERMINAL
PRIMARY TERMINAL
SECONDARY TERMINAL
COMPONENT TEST PROCEDURE
Page 9
5-9
COMPONENTS TEST PROCEDURE RESULTS
HIGH VOLTAGE CAPACITOR
HIGH VOLTAGE DIODE
NOTE : Some inexpensive meters may indicate infinite resistance in both direction.
Measure the resistance. (Ohm-meter scale: Rx1000)
• Terminal to terminal.
Measure the resistance. (Ohm-meter scale: Rx1000)
• Terminal to case.
Measure the continuity (Forward). (Ohm-meter scale: Rx10000)
Measure the continuity (Reverse). (Ohm-meter scale: Rx10000)
Normal: Momentarily indicates
several ohms, and then gradually returns to infinite.
Normal: Infinite.
Normal: Continuity. Abnormal: Infinite.
Normal: Infinite. Abnormal: Continuity.
NOTE: When testing the magnetron, be sure to install the magnetron gasket
in the correct position and be sure that the gasket is in good condition.
Antenna Gasket
Chassis
Filament
Page 10
5-10
COMPONENTS TEST PROCEDURE RESULTS
FUSE
HEATER ELEMENT (Wire leads removed.)
MAGNETRON THERMOSTAT
Check for continuity of the fuse with an multi-meter.
NOTE: If the fuse is blown, check the primary, the secondary, and the monitor switches, H.V.D. and H.V.C. before replacing the fuse. If the fuse is blown by improper switch operation replace the defective switch and the fuse at the same time. Replace just the fuse if the switches operate normally.
NOTE: Make sure heater is fully cooled when tested.
Measure the resistance. (Multi-meter scale: Rx1)
Normal: *Grill heater
Approx. 42 ohm (at 20 ~ 30oC)
*Convection heater
Approx. 40 ohm (at 20 ~ 30oC)
Normal: more than 0.5 Mohm
Normal Abnormal
Measure the resistance with 500V-100M ohm insulation resistance meter.
0°C~Approx.90°C Approx.90°C
0°C~Approx.145°C Approx.145°C
Page 11
5-11
COMPONENTS TEST PROCEDURE RESULTS
Disconnect the 8 pin connector from P.C.B. (Refer to schemetic diagram)
RELAY 2, RELAY 3 OF P.C.B. (Wire leads removed.) Note: Relay Relay 1: Fan motor
Turntable motor
Oven lamp Relay 2: Microwave Relay 3: Grill
FAN MOTOR (Wire leads removed)
TURNTABLE MOTOR (Wire leads removed)
Check for P.C.B. connector.
Measure the resistance. (Ohm-meter scale: R x 1)
Measure the resistance. (Ohm-meter scale: R x 1000)
Normal: Approx. 200 ~400 ohm
Abnormal: Infinite or several
ohm.
Normal: Approx. 10~20 kohm Abnormal: Infinite or several
ohm.
NOTE : • A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS
SERVICED FOR ANY REASON.
• MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION.
• WHEN REMOVING THE WIRE LEADS FROM THE PARTS, BE SURE TO GRASP THE CONNECTOR, NOT THE WIRES.
A
B
Cooking Start OFF
135
Relay 2
Relay 1
Relay 3
Cooking Start OFF
A Approx. 30 ~ 50 ohm
B Approx. 300 ~ 500 ohm
Page 12
COMPONENTS TEST PROCEDURE RESULTS
CIRCULATION MOTOR (Wire leads removed)
NOTE: *( ) = WIRE COLOR
RELAY 4, 6 OF P.C.B (Disconnect the 9 pin connector from P.C.B) See Schematic Dagram on page 4-3)
RELAY 2, 3, 5 OF P.C.B (Wire leads removed.) RY2 : Microwave RY3 : Grill RY5 : Convection
Normal : COM-230V : Approx. 150 Ω Abnormal : Infinite or several ohm.
NOTE : A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS
SERVICED FOR ANY REASON. MAKE SURE THE WIRE LEADS ARE CORRECT POSITION. WHEN REMOVING THE WIRE LEAD FROM THE PARTS, BE SURE TO GRASP THE CONNECTOR, NOT THE WIRES.
5-12
Cooking Start OFF
Cooking Start OFF
COM (YL)
230V(BL)
CN2
1 3 5 7
9
Relay 4
Relay 6
Relay 2 Relay 3 Relay 5
Page 13
5-13
TROUBLE SHOOTING
WHEN YOU GET A COMPLAINT FROM YOUR CUSTOMER, EVALUATE THE COMPLAINT CAREFULLY. IF THE FOLLOWING SYMPTOMS APPLY, PLEASE INSTRUCT THE CUSTOMER IN THE PROPER USE OF THE MICROWAVE OVEN. THIS CAN ELIMINATE AN UNNECESSARY SERVICE CALL.
CAUTIONS
1. Check grounding before checking for trouble.
2. Be careful of the high voltage circuit.
3. Discharge the high voltage capacitor. (See page 2-1)
4. When checking the continuity of the switches or of the high voltage transformer, disconnect one lead wire from these parts and then check continuity with the AC plug removed. To do otherwise may result in a false reading or damage to your meter.
5. Do not touch any part of the circuitry on the digital programmer circuit since static electric discharge may damage this control panel.
Always touch yourself ground while working on this panel to discharge any static charge built up in your
body.
CONDITION
Microwave oven
does not work.
Inserting many plug into one plug outlet and using them at the same time (causes overloading).
Microwave oven plug is not inserted tightly.
Output power is too low. Low AC input voltage.
Food temperature is too low.
Using metallic ware and allowing it to touch the oven wall.
Sparks occurring.
Inconsistent intensity of microwave by their characteristics.
1. Wrap the thinner part with aluminum foil.
2. Use plastic wrap or lid.
3. Stir once or twice while cooking soup, cocoa or milk, etc.
Uneven cooking.
Ceramic ware trimmed in gold or silver powder is used.
Avoid using other electrical appliances when you use the microwave oven.
Insert microwave oven plug securely.
Use the microwave oven at adequate line voltage.
This may not be a defect. It is possible that the food should be cooked for a longer time period.
Do not use metallic ware for cooking except where noted in the cooking guide.
Do not use any type of cookware with metallic trimming.
CAUSE REMEDY
Page 14
5-14
1. Incomplete segments.
• Segment missing.
• Partial segment missing.
• Digit flickering (NOTE: Slight flickering is normal.)
2. Colon does not turn on or blink.
3. A distinct change in the brightness of one or more numbers in display.
4. One or more digits in the display are not lighting.
5. Display indicates a number different from one touched, for example, key in 5 and 3 appears in the display.
6. Specific numbers (for example 7 or 9) will not display when key pad is touched.
7. Display does not count down with time blinking or up with clock operation.
8. Display obviously jumps in time while counting down.
9. Display counts down too fast while cooking.
10. Each indicator light does not turn on after setting cooking cycle.
11. Display time of day does not reappear when cooking is finished.
12. Beep sound is not heard when correct key is touched.
(TROUBLE 1)
The following visual conditions indicate a probable defective control circuit.
CONDITION CHECK RESULT CAUSE REMEDY
1. Some inputs cannot be programmed.
2. Display shows a number or figure different from one touched.
3. Random programming when touching other pads.
4. Display is fixed at some figure and can not accept any input.
Everything works as specified.
Still have trouble.
Defective key membrane assembly.
Defective PCB assembly.
Replace key membrane assembly.
Replace PCB assembly.
Check the connection between leadwire connector and PCB assembly.
Page 15
5-15
CONDITION CHECK RESULT CAUSE REMEDY
1. Fuse blows. Continuity.
No continuity.
Continuity.
Shorted contact at the primary switch.
Replace primary and monitor switches.
No continuity.
Normal.
Defective high voltage capacitor.
Replace high voltage capacitor.
Fuse blows again
Defective high volt­age transformer.
Replace high volt­age transformer.
Malfunction of the monitor switch.
Replace primary and monitor switches.
Check continuity of monitor switch (with door closed).
Check continuity of primary switch (with door opened).
Disconnect one side of the wire lead connected from transformer to the high voltage capacitor and operate the unit.
Replace fuse
(TROUBLE 2)
Oven does not operate at all ; Display window does not display any figures and no input is accepted.
NOTE : All these switches must be replaced at the same time. Refer to page 5-6, 5-7
2. Fuse does not blow.
No continuity.
No continuity.
Replace power supply cord.
Defective mag­netron thermostat.
Defective power supply cord.
Replace mag­netron thermostat.
Check continuity of magnetron thermostat.
Check continuity of power supply cord.
Continuity.
Page 16
5-16
(TROUBLE 3) Display shows all figures set, but oven does not start cooking while
desired program times are set and START pad is touched.
(TROUBLE 4) Oven seems to be operation but little heat is produced in oven load.
CONDITION CHECK RESULT CAUSE REMEDY
1.Setting time does not count down when touching START pad.
2. Fan motor or oven lamp do not turn on.
No continuity.
continuity.
No continuity.
Continuity.
Check the con­nection between connector and P.C.B assembly.
Defective secondary switch.
Replace secondary switch.
Defective P.C.B assembly.
Replace P.C.B assembly.
Check continuity of secondary switch (with door closed).
Check fan motor.
Check oven lamp.
Abnormal.
Abnormal.
Normal.
Defective fan motor.
Defective fan motor.
Replace fan motor.
Replace fan motor.
Loose connection.
Connection then tightly.
CONDITION CHECK RESULT CAUSE REMEDY
Output is low.
Lower than 90% of rating voltage.
Normal.
Abnormal.
Abnormal.
Measure the output power.
Disconnect the wire leads from relay 2 and check on and off time with multitester.
Defective P.C.B assembly.
Replace P.C.B assembly.
Decrease in power source voltage with load.
Suggest customer contact local electric power utility co. or qualified electrician.
Check the power source voltage.
Defective magnetron.
Replace magnetron.
NOTE: Simple test of power output-conducted by heating one liter water for one min. if available.
Page 17
5-17
CONDITION CHECK RESULT CAUSE REMEDY
No microwave oscillation.
No continuity.
Continuity.
Defective P.C.B assembly
Replace P.C.B assembly
Disconnect the wire leads from relay 2 and check continuity of relay2. (Operate the unit)
Abnormal
normal
Defective high voltage transformer.
Replace high voltage transformer .
Check H.V. transformer.
normal
normal
Abnormal
Defective high voltage Diode.
Replace high voltage Diode.
Check H.V. diode.
Abnormal
Defective high voltage capacitor.
Replace high voltage capacitor.
Check H.V. capacitor.
Abnormal
Defective magnetron.
Replace magnetron .
Check Magnetron.
(TROUBLE 5)
No microwave oscillation even though oven lamp and fan motor run
(Display operates properly)
Page 18
5-18
(TROUBLE 7) Grill
CONDITION CHECK RESULT CAUSE REMEDY
1. Heater is not operating.
Abnormal.
Normal.
Normal.
Heater.
Thermostat and relay3.(Grill)
Abnormal.
Malfunction the thermostat.
Malfunction the heater.
Replace.
Wire connection.
No continuity. Open or loosen.
Replace or connect tightly.
Replace.
1. Lower tempera­ture the oven.
Abnormal.
Normal.
Heater.
Thermostat and relay3.(Grill)
Abnormal.
Malfunction the thermostat.
Malfunction the heater.
Replace.
Replace.
(TROUBLE 6) Oven does not cook properly when programmed for the set power level
(Operates properly on HIGH)
CONDITION CHECK RESULT CAUSE REMEDY
Output is full when
you set lower power level.
Abnormal.
Disconnect the wire leads from relay 2 and check continuity relay 2. (Operate the unit)
Defective P.C.B. assembly.
Replace P.C.B. assembly.
NOTE: * Make sure the wore leads correct position.
* When removing the wire leads from parts be sure to grasp the connector not the wires. * When removing the magnetron, be sure to install the magnetron gasket in the correct position and in
good condition.
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