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MICROWAVE OVEN

SERVICE MANUAL

MODEL: LRMM1430SW

LRMM1430SB

CAUTION

BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

P/NO : 3828W5S3066 May, 2003

Printed in Korea

CAUTION

WARNING TO SERVICE TECHNICIANS

PRECAUTIONS TO BE OBSERVED BEFORE

AND DURING SERVICING TO AVOID

POSSIBLE EXPOSURE TO EXCESSIVE

MICROWAVE ENERGY

a. Do not operate or allow the oven to be operated with the door open.

b. Make the following safety checks on all ovens to be serviced before activating the magnetron or other microwave source, and make repairs as necessary; (1) Interlock operation, (2) proper door closing, (3) seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or loosening of hinges and latches, (5) evidence of dropping or abuse.

c. Before turning on microwave for any service test or inspection within the microwave generating compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment, integrity, and connections.

d. Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation and transmission systems shall be repaired 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.

•

Proper operation of the microwave ovens requires that the magnetron be assembled to the wave guide and cavity. Never operate the magnetron unless it is properly installed.

•

Be sure that the magnetron gasket is properly installed around the dome of the tube whenever installing the magnetron.

•

Routine service safety procedures should be exercised at all times.

•

Untrained personnel should not attempt service without a thorough review of the test procedures and safety information contained in this manual.

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FOREWORD

Read this Manual carefully. Failure to adhere to or observe the information in this Manual may result in exposing yourself to the Microwave Energy normally contained within the oven cavity.

MODEL LRMM1430SW

LRMM1430SB

MECHANICAL SERVICE INFORMATION

TABLE OF CONTENTS

1. Adjustment Procedures ....................................................................................................................................... 3-4

2. Precautions on Installation .................................................................................................................................. 5

3. General Precautions in Use................................................................................................................................. 5

4. Trial Operation..................................................................................................................................................... 5

5. Features and Specifications ................................................................................................................................ 5-6

6. Overall Circuit Diagram ....................................................................................................................................... 7-8

7. Operating Procedures ......................................................................................................................................... 9-11

8. Procedure for Measuring Microwave Energy Leakage........................................................................................ 12-13

9. Disassembly Instructions..................................................................................................................................... 14-18

10. Interlock Continuity Test .................................................................................................................................... 19

11. Test and Checkout Procedures, and Troubleshooting

A. Test Procedures............................................................................................................................................. 20-22

B. Checkout Procedures..................................................................................................................................... 23-25

C. Troubleshooting ............................................................................................................................................. 26-30

12. Exploded View................................................................................................................................................... 31-37

13. Replacement Parts List ..................................................................................................................................... 38-41

14. Schematic diagram of P.C.B ............................................................................................................................. 42

A. Printed circuit board ....................................................................................................................................... 43

15.P.C.B Parts List .................................................................................................................................................. 44-46

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1. ADJUSTMENT PROCEDURES

To avoid possible exposure to microwave energy leakage, adjust the door latches and interlock switches, using the following procedure.

ONLY AUTHORIZED SERVICE PERSONNEL

SHOULD MAKE THIS ADJUSTMENT.

The Interlock Monitor and Primary Interlock Switch acts as the final safety switch protecting the user from microwave energy. The terminals between “COM” and

“NC” of the Interlock Monitor must close when the door is opened. After adjusting the Interlock Monitor Switch, make sure that it is correctly connected. See Figures 1-a and 1-b throughout this procedure.

CHECK THE DOOR LATCH AND SWITCH

CLOSINGS.

NOTE: The out case of the microwave oven is removed.

(1) Set the microwave oven on its side so that you can see the latch board and the switches, as shown in

Figure 1-a.

(2) Close the door tightly and check gaps A and B to be sure they are no more than 1/64 ” (0.5 mm). See Figure

1-b for close-up view of gaps A and B (door latches).

If all gaps are less than 1/64 ” (0.5 mm), adjustment of the latch board may not be necessary. Go to Steps 5 and 6 to check the sequence of the switches.

NOTE: To correct sequence of the Primary Interlock

Switch, Secondary Interlock Switch and the

Interlock Monitor Switch is very important.

If any gap is larger than 1/64 ” (0.5 mm), you will need to adjust the latch board-U, L. Go to step 3 and follow all steps in order.

ADJUST THE LATCH AND SWITCH CLOSINGS

(3) Loosen the screw holding the plastic latch board as shown.

(4) With the oven door closed tightly, move the latch board upward toward the top of the oven and/or away from the door latch until the gaps are less than 1/64 ” (0.5 mm).

Hold the latch board tightly in this position until you check the sequence of the switches in steps 5 and 6.

TEST THE LATCH AND SWITCH SEQUENCE

(5) Open the oven door slowly. Watch the door latch, the

Primary Switch. Release Rod and Lever on the switches to make sure they are zero to the body of the switches in the following sequence:

- Primary Interlock Switch

- Secondary Interlock Switch

- Interlock Monitor Switch

Adjust the latch board until the switches operate in this sequence. See Steps 3 and 4.

(6) Close the oven door slowly and be sure it is tightly closed. Watch the three switches to make sure they are zero to the body of the switches in the following sequence:

- Interlock Monitor Switch

- Primary Interlock Switch

- Secondary Interlock Switch

NOTE: The Interlock Monitor Switch is an added safety check on the Primary and Secondary Interlock

Switches. If the Primary and Secondary Interlock

Switches allow the oven to operate with the door open, the Monitor Switch will blow the fuse.

(7) When you achieve the proper sequence of switches in

Steps 5 and 6, tighten the latch board screws at that point.

TEST THE MICROWAVE ENERGY LEAKAGE

(8) Using a survey meter, make sure the microwave energy is below 5 mW/cm.sq.

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DOOR LATCH

LATCH BOARD

SECONDARY

INTERLOCK

SWITCH

MONITOR

INTERLOCK

SWITCH

PRIMARY

INTERLOCK

SWITCH

Figure 1-a

0-1/64"

LATCH BOARD

(A)

-4-

LATCH

(B)

0-1/64"

Figure 1-b

2. PRECAUTIONS ON INSTALLATION

(Figure 2)

A. Plug the power supply cord into a 120 V AC, 60 Hz, single-phase power source with a capacity of at least 20 amperes.

B. Since the unit weights about 38 lbs., be sure to place it on a sturdy and flat surface.

C. Avoid placing the unit in a location where there is direct heat or splashing water.

D. Place the unit as far away as possible from TV, radio, etc. to prevent interference.

CAUTION

This unit is equipped with a 3-prong plug for your safety. If the wall outlet is a grounded 3-hole type, the unit will be grounded automatically.

Properly Polarized and

Grounded Outlet

Three-Pronged(Grounding)

Plug

Figure 2

3. GENERAL PRECAUTIONS IN USE

A. Never operate the unit when it is empty. Operating the oven with no load may shorten the life of the magnetron.

Whenever cooking dry foods (dried fish, bread, etc.) or a small amount of food, be sure to put a glass of water into the cooking compartment. The turntable tray may become hot after operating, be careful when touching it.

B. Aluminum foil should be avoided because it will disrupt cooking and may cause arcing. However, small pieces may be used to cover some parts of food to slow the cooking. Any aluminum foil used should never be closer than 2.5 cm to any side wall of the oven.

4. TRIAL OPERATION

After installation, the following sequences and results should be checked carefully.

A. Put a container filled with water (about 1 liter) into the oven, and close the door tightly.

B. Touch the STOP/CLEAR and the COOK TIME keys. “0” appears in the display window.

C. Set cooking time for 10 minutes by touching “1” and then “0” three times. “10:00” appears in the display window.

D. Touch the START key.

Make sure the cavity light comes on. The unit will begin cooking and the display window will show the time counting down by seconds.

E. After about 5 minutes, make sure the primary interlock switch, the secondary interlock switch and the interlock monitor and oven lamp switch operate properly by opening and closing the door several times. Touch the

START key each time the door is closed.

F. Continue operating the unit. Two short and a long beep sound signal is heard when the time is up. The unit will shut off automatically.

G. Confirm the water is hot.

H. Finally, measure the output power according to

“POWER OUTPUT MEASUREMENT” on page 13.

5. FEATURES AND SPECIFICATIONS

A. The safety systems incorporated in this model are:

(1) Primary interlock switch

(2) Secondary interlock switch

(3) Interlock monitor switch

(4) Choke system

(5) Oven cavity thermostat

(Note: This thermostat located on the oven cavity will open and stop the unit from operation only if a high temperature is reached, such as, a fire created by overcooking food.)

B. Any one of 10 power output levels ranging 0W to 1200W can be selected by the touch control and electronic computer system.

C. Cooking time can be displayed on the digital readout.

D. Three different cooking stages (Include Defrost) can be set. The oven remembers three cooking stages and changes from one cooking stage to another. This is made possible with the memory function of the microprocessor.

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Rated Power Consumption

Output

Frequency

Power Supply

Rated Current

Magnetron Cooling

Microwave Stirring

Rectification

Door Sealing

Safety Devices

Magnetron

Cavity Lamp

Timer

Tray

Overall Dimensions

Oven Cavity Size

Effective Capacity of Oven Cavity

Accessories

SPECIFICATIONS

1250W maximum

1200W maximum (*IEC 60705 Rating standard)

Adjustable 0W through 1200W, 10 steps

2,450 MHz 50 MHz

120V 12V AC, 60Hz

11 Amp.

Forced Air Cooling

Turntable

Rectification Voltage Doubler Half-Wave (Inverter type)

Choke System

Thermostat:

Open at 90 ˚C 5 ˚C

Close at 75 ˚C 5 ˚C

Fuse(20A)

Primary Interlock Switch

Secondary Interlock Switch

Interlock Monitor

2M261

125V, 20W

Digital, up to 99 mm. 99 sec. (in each cooking stage)

Tempered Safety Glass

20 3/4 ” (W) x 15 1/4 ” (D) x 19 1/4 ” (H)

17 1/4 ” (W) x 9 ” (D) x 16 3/4 ” (H)

1.4 Cu.ft.

Owner’s Manual & Cooking Guide ,Turntable, Rotating Ring Assembly.

SWITCH CHART

SWITCH MODE

CONDITIONS

DOOR OPEN

DOOR CLOSED

PRIMARY

INTERLOCK

SWITCH

COM

NO

∞

0

NOTE: Use the above switch chart with circuit diagram on page 7.

SECONDARY

INTERLOCK

SWITCH

COM

NO

∞

0

INTERLOCK

MONITOR

SWITCH

COM

NC

0

∞

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6. OVERALL CIRCUIT DIAGRAM

A. SCHEMATIC DIAGRAM

Figure 3

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B. MATRIX CIRCUIT FOR TOUCH KEY BOARD

Figure 4

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7. OPERATING PROCEDURES

A. CONTROL PANEL

2 3 4 5 9 1 12 14 16 17

6 7 8 10 11 13 15 18 19

Figure 5.

1. Display. The Display includes a clock and indicators that tell you time of day, cooking time settings, and cooking functions selected.

2. Sensor Touch. This pad allows you to cook most of your favorite foods without having to select cooking times and power levels.

3. Homemade Bakery. Homemade bakery has 3 food categories of preset cooking time and power level.

4. Chicken Choices. Chicken Choices has 4 food categories of preset cooking time and power level.

5. Soften. Touch this pad to soften ice cream, cream cheese, butter or frozen juice.

6. Children’s Lunch. Children’s Lunch has 3 food categories of preset cooking time and power level.

7. Fast Breakfast. Fast Breakfast has 3 food categories of preset cooking time and power level.

8. Melt. Touch this pad to melt chocolate, cheese, butter or marshmallows.

9. Auto Defrost. This pad is an accurate defrosting method for meat, poultry, fish and bread.

10. Q-Defrost. Touch this pad to defrost foods quickly.

11. More / Less. Touch these pads to adjust cooking time in 10 second increments.

12. Cook time. Touch this pad to set a cooking time.

13. Power. Touch this pad to set a cooking power.

14. Clock. Touch this pad to enter the time of day.

15. Kitchen Timer. Touch this pad to use your microwave oven as a kitchen timer.

16. Number pads. Touch Number pads to enter cooking time, Power level, quantities, or weights.

17. Stop/Clear. Touch this pad to stop the oven or clear entries. Also used to turn Child Lock on and off.

18. Ez-ON. You can extend cooking time in multiples of 30 seconds by repeatedly touching this pad during cooking.

19. Start. Touch this pad to start the oven.

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B. PANEL INSTRUCTIONS (Figure 5)

The entire operation is done by simple touch control pads.

(1) Display Window

Numbers and letters explained in Figure 5 are shown in the display window (Vacuum Fluorescent Tube).

(a) The Time in four digits (12-hour indication): 00 Hour

00 Minute.

(b) Cooking Time of Day in four digits 00 Minutes 00

Seconds.

(c) Power Control Level in three digits: P-000

(d) Each Indicator Light shows which function is set and involved in the course of cooking by turning itself on.

Indicator Lights automatically go out upon completion of cooking.

(2) SENSOR COOK key

Use humidity sensor for certain food item.

(3) HOMEMADE BAKERY key

3 food categories of preset cooking time and power level.

(Roll/Muffin, Pancake & French Toast)

(4) CHICKEN CHOICES key

4 food categories of preset cooking time and power level.

(Chicken Wings, Chicken Nuggets, Spicy Chicken &

Mexican Chicken )

(5) CHILDREN’S LUNCH key

3 food categories of preset cooking time and power level.

(Hot Dog Buns, Frozen Pizza & Canned Pasta)

(6) FAST BREAKFAST key

3 food categories of preset cooking time and power level.

(Oatmeal, Bacon & Scrambled Eggs)

(7) CLOCK Key

Used in setting Time of Day.

(8) COOK TIME Key

The TIME key is used to set the cooking time. Touch the

TIME key and then the number keys that correspond to the desired cooking time. The remaining time is continuously displayed during cooking.

(9) STOP/CLEAR Key

Used to stop the oven or clear all entries except

CLOCK.

(10) AUTO DEFROST key (DEFROST MEAT, POULTRY,

FISH & BREAD)

Used in setting AUTO DEFROST.

(11) Q DEFROST key

Used in setting QUICK DEFROST.

(12) KITCHEN TIMER Key

Used as a kitchen timer.

(13) POWER Key

Used to select cooking power level.

(14) Ez-ON Key

It will add 30 seconds up to 3 minutes 30 seconds: after 3 minutes 30 seconds, every touch will add 1 minute up to 99 minutes 59 seconds.

(15) START Key

Touch the START key after setting the desired cooking times etc. Also touch the START key to resume cooking after the cooking is temporarily stopped by opening the door. The key will not function unless the door is closed.

(16) Soften

Used to soften ice cream, cream cheese, butter or frozen juice.

(17) Melt

Used to melt chocolate, cheese, butter or marshmallows.

(18) More/Less

Used to adjust cooking time in 10 second increments.

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C. EASY USE CHART

(1) CLOCK

1. Touch STOP/CLEAR.

2. Touch CLOCK.

3. Touch numbers for correct time of day.

4. Touch CLOCK.

(2) “HI-POWER” COOKING

1. Touch STOP/CLEAR.

2. Touch COOK TIME.

3. Touch numbers for desired cooking time.

4. Touch START.

(3) “MULTI-STAGE” COOKING

1. Touch STOP/CLEAR.

2. Touch COOK TIME.

3. Touch numbers for cooking time.

4. Touch POWER.

5. Touch number for cooking power level.

6. Repeat steps 2-5 to set 2nd cooking stage.

7. Touch START.

(4) CHILD LOCK

To set:

1. Touch STOP/CLEAR.

2. Hold STOP/CLEAR more than 2 seconds.

To cancel:

1. Touch STOP/CLEAR.

2. Hold STOP/CLEAR more than 2 seconds.

(5) SOFTEN

1. Touch STOP/CLEAR.

2. Touch SOFTEN.

Four different soften menus are provided.

3. Select Menu 1 to 4- See cooking guide.

4. Enter the amount of the Category.

(6) MELT

1. Touch STOP/CLEAR.

2. Touch MELT.

Four different melt menus are provided.

3. Select Menu 1 to 4- See cooking guide.

4. Enter the amount of the Category.

(7) AUTO DEFROST

1. Touch STOP/CLEAR.

2. Touch AUTO DEFROST.

Three different defrosting category are provided.

(MEAT, POULTRY, FISH, BREAD)

3. Enter the weight of your food.

4. Touch START

5. At beeping, turn food over by following the instructions in the manual.

6. After turning food over, touch START to resume defrosting.

(8) Q DEFROST

1. Touch STOP/CLEAR.

2. Touch Q DEFROST.

(9) KITCHEN TIMER

1. Touch STOP/CLEAR.

2. Touch KITCHEN TIMER.

3. Touch correct numbers for time.

4. Touch START.

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8. PROCEDURE FOR MEASURING MICROWAVE

ENERGY LEAKAGE

A. CAUTIONS

(1) Be sure to check a microwave emission prior to servicing the oven if the oven is operative prior to servicing.

(2) The service personnel should inform the manufacturer, importer, or assembler of any certified oven unit found to have a microwave emission level in excess of

5mW/cm.sq. and 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.

(3) If the oven operates with the door open, the service personnel should;

- Tell the user not to operate the oven

- Contact the manufacturer and CDRH (Center for

Devices and Radiological Health) immediately.

NOTE: Address on CDRH

Office of Compliance (HFZ-312)

Center for Devices and Radiological Health

1390 Piccard Drive Rockville, Maryland 20850

(4) The service personnel should check all surface and vent openings for microwave emission testing.

(5) Check for microwave energy leakage after every servicing. The power density of the microwave radiation leakage emitted by the microwave oven should not exceed 1mW/cm.sq. And always start measuring of an unknown field to assure safety for operating personnel from radiation leakage.

NOTE: The standard is 5mW/cm.sq. while in the customer’s home. 1mW/cm.sq. stated here is manufacturer’s own voluntary standard for units in customer’s home.

EQUIPMENT

Electromagnetic energy leakage monitor (NARDA

8100B, HOLADAY HI 1501)

600cc glass beaker

Glass thermometer 100 0 C

B. MEASURING MICROWAVE ENERGY LEAKAGE

(1) Pour 275 15cc of 20 5 ˚C water in a beaker which is graduated to 600 cc, and place the beaker in the center of the oven.

(2) Set the energy leakage monitor to 2,450 MHz and use it following the manufacturer’s recommended test procedure to assure correct result.

(3) When measuring the leakage, always use the 2 inch

(5 cm) spacer supplied with the probe.

(4) Operate the oven at its maximum output.

(5) Measure the microwave radiation using and electromagnetic radiation monitor by holding the probe perpendicular to the surface being measured. (See Figure 7)

Move probe along shaded area.

Probe scanning speed less than 2.5 cm/sec.

Figure 7

C. MEASUREMENT WITH THE OUT CASE REMOVED

(1) 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.

- Around the magnetron

- The waveguide

WARNING: AVOID CONTACTING ANY HIGH VOLTAGE

PARTS.

Figure 6

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D. MEASUREMENT WITH A FULLY ASSEMBLED OVEN

(1) After all components, including the outer panels, are fully assembled, measure for microwave energy leakage around the door viewing window, the exhaust opening and air inlet openings.

(2) Microwave energy leakage must not exceed the values prescribed below.

NOTES:

Leakage with the outer panels removed - less than

5mW/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 1 mW/cm

.sq.

E. NOTE WHEN MEASURING

(1) Do not exceed meter full scale deflection.

(2) The test probe must be removed no faster than 1 inch/sec (2.5cm/sec) along the shaded area, otherwise a false reading may result.

(3) 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.

(4) 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.

F. RECORD KEEPING AND NOTIFICATION AFTER

MEASUREMENT

(1) 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.

(2) Should the microwave energy leakage not be more than 1mW/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.

(3) At least once a year, have the electromagnetic energy leakage monitor checked for calibration by its manufacturer.

G. POWER OUTPUT MEASUREMENT

Be sure oven cavity is clean and cool .

(not used recently)

(1) Fill the test beaker with 59 ˚F(15 ˚C) ~ 75 ˚F(24 ˚C) 1 liter tap water.

(2) Stir the water in the beaker with thermometer (˚F or ˚C) and measure temperature as T1.

(3) Place the beaker on the center of turntable.

(4) Set for one (1) minute.

(5) When the heating is finished, stir the water again with thermometer and measure the temperature of water as T2.

(6) Subtract T1 from T2, this will give you the temperature rise.

(7) The microwave power output is within specification, if the temperature rise is as shown below:

Voltage

(VAC under load)

120V

108V

Temperature Rise

°C

13 - 15

11.5 - 13.5

°F

23.4 - 27

20.7 - 24.3

(8) Power output will be influenced by line voltage of power supply. Consequently, correct power output must be measured within 120V AC 1 Volt while unit is operating.

SPECIAL TIP

• This oven used the button head screws.

Button Head

(Torx style 2)

• When you remove the screws, using the tamper-resistant Torx driver have a pin-in-head.

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9. DISASSEMBLY INSTRUCTIONS

IMPORTANT NOTES:

UNIT MUST BE DISCONNECTED FROM ELECTRICAL

OUTLET WHEN MAKING REPAIRS, RE-PLACEMENTS,

ADJUSTMENTS AND CONTINUITY CHECKS. WAIT AT

LEAST ONE MINUTE, UNTIL THE HIGH VOLTAGE

CAPACITOR IN THE HIGH VOLTAGE POWER SUPPLY

HAS FULLY DISCHARGED.

THE CAPACITOR SHOULD BE DISCHARGED BY USING

INSULATED WIRE - I.E. TEST PROBE CONNECTED TO

10K-OHM RESISTOR IN SERIES TO GROUND.

WHEN RECONNECTING THE WIRE LEADS TO

ANY PART, MAKE SURE THE WIRING CONNECTIONS

AND LEAD COLORS ARE CORRECTLY MATCHED

ACCORDING TO THE OVERALL CIRCUIT DIAGRAM.

(ESPECIALLY SWITCHES AND HIGH VOLTAGE

CIRCUIT.)

A. REMOVING OUT CASE (Figure 8)

(1) Unfasten five screws from the rear section.

(2) Unfasten two screws from the side section.

(3) Push the out case back about 1 inch (3cm).

(4) Lift the case from the set.

Remove deco front

Disconnect the lead wires

Remove choke cap

Choke Cap

Figure 8

B. DOOR ASSEMBLY REMOVAL (Figure 9)

(1) Remove out case.

(2) Unfasten two screws for removing deco front.

(3) Disconnect the lead wires from main board and pull that out from the cavity.

(4) Remove the choke cap very carefully with a flat-blade screw driver.

(5) Lift up and pull out Door assembly carefully from the cavity.

CAUTION: Be careful not to damage door seal plate with the screw driver.

Remove door

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Figure 9

C. REMOVING CONTROL CIRCUIT BOARD (Figure 10)

(1) Remove out case.

(2) Remove door assembly.

(3) Unfasten two screws.

(4) Lift up and pull out control panel assembly carefully from the cavity.

(5) Remove door frame.

(6) Remove the F.P.C connector from the terminal socket.

(7) Unfasten two screws which tighen the circuit board.

(8) Remove control circuit board from the door panel assembly.

Unfasten screws

Door frame securing

D. SEPARATE CAVITY AND BASE PLATE (Figure 11)

(1) Remove out case.

(2) Remove Door Assembly.

(3) Remove five screws at the base plate.

(Front 3 EA, Back 2 EA).

(4) Disconnect the lead wires from filter.

(5) Disconnect all the lead wires from main board.

(6) Disconnect the MGT high voltage lead wire and turn table motor lead wire.

(7) Lift up the cavity and disconnect the fan motor lead wire.

CAUTION: BE CAREFUL NOT TO DAMAGE LEAD

WIRE.

Unfasten screws

F.P.C.Connector

Control Panel

Figure 10

Remove screw

Circuit Board

Disconnect the lead wires

Figure 11

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E. AIR GUIDE REMOVAL (Figure 12)

(1) Separate cavity and base plate.

(2) Unfasten the screws which hold the air guide in the base plate.

(3) Unfasten the air guide from hook.

F. POWER BOARD AND INVERTER MODULE AND

SUCTION GUIDE (Figure 12)

(1) Separate cavity and base plate.

(2) Remove air guide.

(3) Unfasten the screws.

(4) Lift up the power board, inverter module and suction guide.

G. SENSOR DUCT REMOVAL (Figure 13)

(1) Remove out case.

(2) Unfasten the sensor duct screw.

(3) Disconnect sensor lead wire.

(4) Pull the sensor duct out.

Figure 13

Figure 12

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H. MAGNETRON REMOVAL

(1) Disconnect the leadwire from the magnetron.

(2) Carefully remove the mounting screws holding the magnetron at the waveguide.

(3) Remove the magnetron 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/cm 2 .

(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.

I. REMOVING THE TURNTABLE MOTOR

(1) Remove the turntable and turntable roller rest.

(2) Lay the unit down on its back.

(3) Remove the turntable motor cover.

The turntable base cover is easily removed by pinching the four parts with a wire cutting.

(4) Disconnect the leadwire from the turntable motor terminals.

(5) Remove the screw securing the turntable motor to the oven cavity ASSEMBLY.

(6) After repairing the motor, rotate the removed turntable motor cover.

(7) Fit the turntable motor cover’s projecting part to the base plate slit.

NOTE:

1. Remove the lead wires from the turntable motor VERY

CAREFULLY.

2. Be sure to grasp the connector, not the wires, when removing.

Magnetron

Magnetron

Magnetron

Gasket

Waveguide

Bracket

Dome

Waveguide

Figure 14

-17-

Lead Wires

Turntable Motor

Figure 15

J. FAN MOTOR ASSEMBLY REMOVAL

(1) Separate cavity and base plate.

(2) Remove air and suction guide..

(3) Remove the two screws holding the fan motor ASSEMBLY to the suction guide ASSEMBLY.

(4) Disconnect the wires and unfasten the screws.

(5) Pull out the Fan motor from the suction guide.

Inverter

Fan Motor ASS’Y

Suction

Guide

K. 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.

• Check for play in the door by pushing the door release button. Door movement should be less than

0.5 mm. (1/64 inch)

Don't push the door release button while making this adjustment. Make sure that the latch moves smoothly after adjustment is completed and that the screws are tight.

Make sure the primary, monitor, and secondary switches operate properly by following the continuity test procedure.

ADJUSTMENT

DIRECTION

SECONDARY

SWITCH

Figure 16

MONITOR

SWITCH

PRIMARY

SWITCH

Figure 17

-18-

10. INTERLOCK CONTINUITY TEST

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 OR V-5230Q FOR PRIMARY SWITCH

TYPE NO. SZM-V 16-FA-62 OR VP-532A-OF OR V-5220Q FOR MONITOR SWITCH

TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF OR V-5230Q FOR SECONDARY SWITCH

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.

COMPONENTS

SWITCHES

(Lead wires removed)

TEST PROCEDURE

Check for continuity of the switch with an Ohm-meter

Primary

Switch

COM

NO

Door open

RESULTS

Door closed

Monitor

Switch

Secondary

Switch

COM

NC

COM

NO

NOTE : After checking for the continuity of switches, make sure that they are connected correctly.

-19-

11. TEST AND CHECKOUT PROCEDURES, AND TROUBLESHOOTING

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 LEAD WIRES FROM THE INVERTER MODULE.

2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER OF

WATER IN CONTAINER) IN THE OVEN.

A. TEST PROCEDURES

COMPONENTS

INVERTER

(Lead wires removed)

TEST PROCEDURE RESULTS

CN702

Heat Sink

E701

120V AC

MAGNETRON

(Lead wires removed)

CN701

High Voltage

Output to

Magnetron

CN703

Control Signal

In/Out

Note: Do not try to repair the inverter board, nor try to make any adjustments to the board.

Check wiring to the inverter:

1. Unplug the oven’s main power supply.

2. Visually inspect 4 connectors on the inverter board: CN701, CN702, CN703, E701 to see whether there are any signs of failure due to loose wires, bad crimping, sign of overheating, etc.

1. Measure the resistance.

(Ohm-meter scale: Rx1)

• Filament terminal

2. Measure the resistance.

(Ohm-meter scale: Rx1000)

• Filament to chassis

Normal: Less than 1 ohm

Normal: Infinite

-20-

COMPONENTS

SENSOR

TEST PROCEDURE

Antenna

Gasket

Chassis

RESULTS

Filament

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.

1. Disconnect sensor connector from micom computer board.

2. Measure resistance terminal to terminal

(Select the ohm scale on the meter)

Normal: Approximately

BK-RD: 5.2 Kohms

RD-WH: 2.1 Kohms

BK-WH: 2.1 Kohms

Abnormal:

Infinite or several

*Sensor cooking condition

1. Oven should be plugged in at least 5 minutes before sensor cooking.

2. Room temperature should not exceed 95˚F.

3. Be sure the exterior of the cooking container and the interior of the oven are dry.

4. The oven will not generate microwave energy for the first

28 seconds of the sensor cooking cycle.

NOTE: MAKE SURE THE LEAD WIRES ARE

IN THE CORRECT POSITION.

WHEN REMOVING THE LEAD

WIRES FROM THE PARTS, BE

SURE TO GRASP THE

CONNECTOR, NOT THE WIRES.

-21-

COMPONENTS

RELAY

TEST PROCEDURE

Check for continuity of relay with an ohm-meter.

(Remove lead wires from relay and operate the unit.)

RESULTS

Normal: Approx.

ON: 0 ohm

OFF:

∞ ohms

Abnormal: Infinite or several ohms.

Relay 2

FAN MOTOR

(Wire leads removed)

Measure the resistance.

(Ohm-meter scale: R x 100)

A(RD)

B(BK)

C(WH)

Normal: Approx. 50 ~ 150 ohms

Abnormal: Infinite or several ohms.

TURNTABLE

MOTOR

(Wire leads removed)

Measure the resistance.

(Ohm-meter scale: R x 1000)

Normal: Approx. 2 ~ 4K ohms

Abnormal: Infinite or several ohms.

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.

-22-

B. CHECKOUT PROCEDURES

(1) CHECKOUT PROCEDURES FOR FUSE BLOWING

CAUTION: REPLACE BLOWN FUSE WITH 20 AMPERE FUSE.

PROBLEMS CAUSES

Fuse blows immediately after the door is closed.

Fuse blows immediately after the door is opened.

Improper operation of the primary interlock, secondary interlock switches and/or the interlock monitor switch.

Fuse blows when the door is closed and START key is touched.

Malfunction of the Inverter, the magnetron, the fan motor or the circuit board.

NOTES:

- If the fuse is blown by an improper switch operation, replace the defective switches and the fuse at the same time.

After replacing the defective switches with new ones, make sure that they are correctly connected.

- Check for microwave energy leakage according to “1. ADJUSTMENT PROCEDURES” on page 3, when the primary interlock, secondary interlock switches and/or the interlock monitor switches are adjusted or replaced.

-23-

(2) CHECKOUT PROCEDURES FOR RELAY

- PROBLEM (A) -

FAN motor and oven lamp turn on without touching

START key when the door is closed.

NO YES

GOOD

Remove the mate connector of I/O

CON from the circuit board does the unit still operate?

NO

Replace the circuit board

- PROBLEM (B) -

FAN motor and oven lamp turn on When the door is closed and START key is touched.

YES NO

GOOD Check the interlock switches

NO YES

Replace the micro switches.

Defective

RELAY or poor connection of relay

Replace

RELAY or correct the connection.

-24-

(3) CHECKOUT PROCEDURES FOR CIRCUIT BOARD

The following symptoms indicate a defective circuit board.

(1) Check the input current. If the input current is more than 20A, check the magnetron and wiring. If the input current is less than 0.5 A, there is no input to the inverter.

(2) The start function fails to operate but the interlock switches, the door sensing and the relay check good.

(3) The unit with a normal relay continuously operates.

(4) The buzzer does not sound or continues to sound.

(5) Some segments of one or more digits do not light up, or they continue to light up, or segments light when they should not.

(6) Wrong figures appear.

(7) The figures of all digits flicker.

(8) Some of the indicators do no light up.

(9) The clock does not keep time properly.

NOTE: A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS

SERVICED FOR ANY REASON.

-25-

C. 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 Inverter.

3. When checking the continuity of the switches or of the inverter, 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.

4. Do not touch any part of the circuit on the PCB since static electric discharge may damage this control panel.

Always touch yourself to ground while working on this panel to discharge any static charge built up in your body. (Micom model only)

CONDITION

Microwave oven does not work.

Output power is too low.

Sparks occur.

Uneven cooking.

CAUSE

Inserting many plugs into one outlet and using them at the same time.

(blown fuse or breaker)

Microwave oven plug is not inserted tightly.

Low AC input voltage.

Food temperature is too low.

Using metallic ware and allowing it to touch the oven wall.

Ceramic ware trimmed in gold or silver powder is used.

Inconsistent intensity of microwave by their characteristics.

-26-

REMEDY

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.

1. Use plastic wrap or lid.

2. Stir once or twice while cooking soup, cocoa or milk, etc.

(TROUBLE 1) The following visual conditions indicate a probable defective control circuit.

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.

CONDITION

1. No input can be programmed.

2. Some inputs cannot be programmed.

3. Display shows a number or figure different from one touched.

4. Random programming when touching other pads.

5. Display is fixed at some figure and can not accept any input.

CHECK

Check the connection between membrane key assembly and

PCB assembly.

Replace key membrane assembly and check operation.

RESULT

Continuity

No continuity

Everything works as specified.

Still have trouble.

CAUSE

Defective PCB assembly.

Loose connection.

Defective key membrane assembly.

Defective PCB assembly.

REMEDY

Replace PCB assembly.

Connect them tightly.

Replace key membrane assembly.

Replace PCB assembly.

-27-

(TROUBLE 2) Oven does not operate at all, Display window does not display any figures, and no input is accepted.

CONDITION

1. Fuse blows.

CHECK

Check continuity of monitor switch (with door closed).

RESULT

Continuity.

No continuity.

CAUSE

Malfunction of the monitor switch.

Replace fuse

Check continuity of primary switch (with door opened).

Continuity.

No continuity.

Shorted contact at the primary switch.

REMEDY

Replace fuse, primary, monitor switches, and

RELAY of P.C.B

Assembly.

Replace fuse, primary, monitor switches, and

RELAY of P.C.B

Assembly.

Disconnect one side of the lead wires connected from Inverter.

Normal.

Fuse blows again

Defective control

PCB.

Defective Inverter.

Replace Inverter.

Replace control

PCB.

NOTE : All these switches must be replaced at the same time. Refer to page 18, 19

2. Fuse does not blow.

Check continuity of thermostat.

No continuity.

Continuity.

Defective thermostat.

Check continuity of power supply cord.

No continuity.

Replace thermostat.

Defective power supply cord.

Replace power supply cord.

-28-

(TROUBLE 3) Display shows all figures set, but oven does not start cooking while desired program times are set and START pad is touched.

CONDITION CHECK RESULT

1. Setting time does not count down when touching START pad.

Check continuity of secondary switch (with door closed).

No continuity.

Continuity.

CAUSE

Defective secondary switch.

2. Fan motor or oven lamp do not turn on.

Check the connection between

CN1 connector and PCB assembly.

Check fan motor.

Check oven lamp.

Continuity

No continuity

Abnormal

Abnormal

Normal

Defective Power

PCB assembly.

Loose connection.

Defective fan motor.

Defective oven lamp.

REMEDY

Replace secondary switch.

Replace Power

PCB assembly.

Connect them tightly.

Replace fan motor.

Replace oven lamp.

(TROUBLE 4) Oven seems to be operating but little heat is produced in oven load.

CONDITION CHECK

Output is low

Check the power source voltage.

RESULT

Lower than 90% of rating voltage.

Normal

CAUSE

Decrease in power source voltage with load.

Defective

Magnetron.

REMEDY

Suggest customer contact local electric power utility co. or qualified electrician.

Replace

Magnetron.

NOTE : Simple test of power output-conducted by heating one liter water for one min. if available.

Minimum 8.5°C temperature rise is normal condition.

-29-

(TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run.

(Display operates properly)

CONDITION

No microwave oscillation.

CHECK

Disconnect the wire leads from relay and check continuity of relay. (Operate the unit)

RESULT

No continuity.

Continuity.

CAUSE

Defective PCB assembly.

Replace Inverter and Magnetron.

REMEDY

Replace PCB assembly.

NOTE : • Make sure the wire leads correct position.

• When Removing the lead wires from the 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.

Output is full power when you set lower power level.

Disconnect the lead wires from relay and check continuity relay .

(Operate the unit)

Abnormal.

Defective PCB assembly.

Replace PCB assembly.

-30-

#EV#

INTRODUCTION

EXPLODED VIEW

-31-

#EV#

DOOR PARTS

15006A

13581A

13536A

13552A

13551A

13213A

WTP002

268711

14970A

WTP002

14026A

23506A

-32-

#EV#

CONTROLLER PARTS

13551A

WTP002

268711

23506A

-33-

#EV#

OVEN CAVITY PARTS

33112U

WSZ185

WTT022 :Model LRMM 1430SW

WTT020 :Model LRMM 1430SB

33052A

36549S

WTP013

13806F

647781

-34-

33390G

35889A

#EV#

LATCH BOARD PARTS

43501A

466001

WSZ085

43500A

466003

466001

-35-

#EV#

OVEN INTERIOR PARTS

WTT028

56501A

WTT021

54974T

56930V

WSZ002

56324A

-36-

43500A

56912B

#EV#

BASE PLATE PARTS

56411A

WTT028

WTT028

268712

WTT028

35264A

568772

56851H

568771

WTT021

WSZ002

WTT028

56549F

WTT034

568711

55238A

55900A

50FZZA

56201A

54980A

63302A

647782

54974S

43501A

-37-

SCHEMATIC DIAGRAM OF P.C.B

-42-

PRINTED CIRCUIT BOARD

KEY PCB

MAIN PCB

-43-