Lg LMV1650ST Microwave Service manual

Website: http://us.lgservice.com

MICROWAVE OVEN

SERVICE MANUAL

MODEL: LMV1645SW

LMV1645SB

LMV1645SBQ

LMV1645ST

LMV1650ST

CAUTION

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

July, 2005

Printed in Korea P/NO : 3828W5S5176

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 power 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, replaced, or adjusted by procedures described in this manual before the oven is released to the owner.

e. A Microwave leakage check to verify compliance with the Federal performance standard should be performed on each oven prior to release to the owner.

• 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.

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.

TABLE OF CONTENTS

(Page)

SAFETY PRECAUTIONS ................................................................................................................Inside front page

SPECIFICATIONS ................................................................................................................................................ 1-1

CAUTIONS ........................................................................................................................................................... 2-1

INSTALLATIONS .................................................................................................................................................. 3-1

OPERATING INSTRUCTIONS............................................................................................................................. 4-1

CONTROL PANEL .......................................................................................................................................... 4-1

CONTROL PANEL INSTRUCTIONS............................................................................................................... 4-2

OVERALL CIRCUIT DIAGRAM ............................................................................................................................ 5-1

SCHEMATIC DIAGRAM (I).............................................................................................................................. 5-1

SCHEMATIC DIAGRAM (II)............................................................................................................................. 5-2

MATRIX CIRCUIT FOR TOUCH KEY BOARD ............................................................................................... 5-3

GENERAL INFORMATION FOR SERVICE ......................................................................................................... 6-1

GENERAL PRECAUTIONS IN USE ............................................................................................................... 6-1

TRIAL OPERATION ........................................................................................................................................ 6-1

FEATURES AND SPECIFICATIONS FEATURES .......................................................................................... 6-1

SERVICE INFORMATION .................................................................................................................................... 7-1

PRECAUTIONS AND REPAIR SERVICE TIPS .............................................................................................. 7-1

MICROWAVE LEAKAGE TEST ...................................................................................................................... 7-2

POWER OUTPUT MEASUREMENT............................................................................................................... 7-3

DISASSEMBLY INSTRUCTIONS ................................................................................................................... 7-4

INTERLOCK SYSTEM .................................................................................................................................. 7-12

INTERLOCK CONTINUITY TEST ................................................................................................................. 7-14

TEST AND CHECKOUT PROCEDURES AND TROUBLESHOOTING........................................................ 7-15

A. TEST PROCEDURES ........................................................................................................................... 7-15

B. CHECKOUT PROCEDURES ................................................................................................................ 7-20

C. TROUBLESHOOTING .......................................................................................................................... 7-22

EXPLODED VIEW ................................................................................................................................................ 8-1

REPLACEMENT PART LIST................................................................................................................................ 9-1

SPECIFICATIONS

Rated Power Consumption ................................ 1560W maximum (Microwave oven+Cook top lamps+Ventilation fan)

Microwave Output ............................................... 1000W (IEC60705)

Frequency .......................................................... 2450 MHz ±50 MHz

Power Supply ..................................................... 120 VAC, 60 Hz

Rated Current .................................................... 13.3 Amp. (Microwave oven+Cook top lamps+Ventilation fan)

Magnetron Cooling ............................................. Forced Air Cooling

Rectification ....................................................... Rectification Voltage Double Half-Wave

Door Sealing ...................................................... Choke System

Safety Devices ................................................... Magnetron Thermostat: Open at 145 °C ± 5 °C

Close at 60 °C ± 5 °C

............................................................................

Oven Thermostat: Open at 110 °C ± 5 °C

Close at 0 °C ± 5 °C

............................................................................

Fuse(20A)

............................................................................

Primary Interlock Switch

............................................................................

Secondary Interlock Switch

............................................................................

Interlock Monitor Switch

Magnetron .......................................................... 2M246 - 310GT

Cook top Lamp ................................................... 120 V, 30 W

Cavity Lamp ....................................................... 125 V, 30 W or 40 W

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

Tray .................................................................... Tempered Safety Glass

Overall Dimensions ............................................ 29

15

/

16

”(W)x16

7

/

16

”(H)x15

3

/

8

”(D)

Oven Cavity Size ............................................... 20

7

/

8

”(W)x9

3

/

16

”(H)x14

3

/

16

”(D)

Effective Capacity of Oven Cavity ...................... 1.6 Cu.ft.

Accessories ........................................................ Owner’s Manual & Cooking Guide, Installation Manual,

............................................................................

Exhaust Adapter, Exhaust Damper, Mounting Kit and Filter,

............................................................................

Support, Hub, Glass Tray, Metal Rack.

SWITCH CHART

SWITCH MODE

CONDITIONS

DOOR OPEN

DOOR CLOSED

PRIMARY

INTERLOCK

SWITCH

COM

NO

OPEN

CLOSE

NOTE:

Use the above switch chart with circuit diagram on page 5-1.

SECONDARY

INTERLOCK

SWITCH

COM

NO

OPEN

CLOSE

INTERLOCK

MONITOR

SWITCH

COM

NC

CLOSE

OPEN

1-1

CAUTIONS

Unlike other appliances, the microwave oven is high-voltage and high-current equipment.

Though it is free from danger in ordinary use, extreme care should be taken during repair.

• DO NOT operate on a 2-wire extension cord during repair and use.

• NEVER TOUCH any oven components or wiring during operation.

• BEFORE TOUCHING any parts of the oven, always remove the power plug from the outlet.

• Remove your watches whenever working close to or replacing the Magnetron.

• DO NOT touch any parts of the control panel circuit. A resulting static electric discharge may damage this P.C.B.

• NEVER operate the oven with no load.

• NEVER injure the door seal and front plate of the oven cavity.

• NEVER put iron tools on the magnetron.

• NEVER put anything into the latch hole and the interlock switches area.

MICROWAVE RADIATION

Personnel should not be exposed to the microwave energy which may radiate from the magnetron or other microwave generating device if it is improperly used or connection.

All input and output microwave connections, waveguide, flange, and gasket must be secure never operate the device without a microwave energy absorbing load attached.

Never look into an open waveguide or antenna while the device is energized.

• Proper operation of the microwave oven requires that the magnetron be assembled to the waveguide 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.

ANTENNA

Gasket

COOLING FIN

MAGNETRON

CHASSIS GROUND

MAGNETRON

FILAMENT

TERMINALS

THE OVEN IS TO BE SERVICED ONLY

BY PROPERLY QUALIFIED SERVICE

PERSONNEL.

2-1

INSTALLATIONS

BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY.

PRECAUTIONS ON INSTALLATION

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

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

C. Install the unit on the mounting plate firmly.

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

GROUNDING INSTRUCTIONS

For personal safety, this appliance must be fully grounded at all times.

In the event of an electrical short circuit, grounding reduces the risk of electrical shock.

The plug must be plugged into an outlet that is properly installed and grounded.

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.

Plug with Ground

Prong

Properly Polarized and Grounded

Outlet

WARNING

Improper use of the grounding plug can result in a risk of electric shock.

Do not, under any circumstances, cut or remove the third ground prong from the power cord plug.

3-1

CONTROL PANEL

OPERATING INSTRUCTIONS

1

14

18

21

23

25

26

2

3

5

8

9

11

4

7

6

10

13

12

15

16

17

20

19

22

24

27

4-1

CONTROL PANEL INSTRUCTIONS

1. DISPLAY:

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

2. POPCORN:

Touch this pad when popping popcorn in your microwave oven. The oven’s sensor will tell the oven how long to cook depending on the amount of humidity it detects from the popcorn.

3. POTATO:

Touch this pad to cook potatoes. The oven’s sensor will tell the oven how long to cook depending on the amount of humidity it detects from the potato.

4. PIZZA:

Touch this pad to reheat pizza. The oven’s sensor will tell the oven how long to reheat depending on the amount of humidity it detects from the pizza.

5. VEGETABLE:

Touch this pad to cook vegetables.

The oven’s sensor will tell the oven how long to cook depending on the amount of humidity it detects from the vegetables.

6. COOK:

Touch this pad to cook frozen entree, casserole, and rice. The oven’s sensor will tell the oven how long to cook depending on the amount of humidity coming from the food.

7. REHEAT:

Touch this pad to reheat dinner plate, soup/sauce, and casserole. The oven’s sensor will tell the oven how long to reheat depending on the amount of humidity coming from the food.

8. CUSTOM COOK:

Touch this pad to recall one cooking instruction previously programmed into memory.

9. TIME COOK:

Touch this pad to set a cooking time.

10. POWER LEVEL:

Touch this pad to select a cooking power level.

11. AUTO DEFROST:

Meat, poultry, fish. Touch this pad to select food type and defrost food by weight.

12. TIME DEFROST:

Touch this pad to defrost most other frozen foods.

13. Q DEFROST:

This pad provides you with the

RAPID defrosting method for 1.0 pound frozen foods.

14. NUMBER:

Touch number pads to enter cooking time, power level, quantities, or weights.

15. CUSTOM SET:

Touch this pad to change the oven’s default settings for sound, clock, display speed and defrost weight.

16. CLOCK:

Touch this pad to enter the time of day.

17. KITCHEN TIMER:

Touch this pad to set the kitchen timer.

18. MORE:

Touch this pad to add ten seconds of cooking time each time you press it.

19. LESS:

Touch this pad to subtract ten seconds of cooking time each time you press it.

20. HOLD WARM:

Touch this pad to keep hot, cooked foods warm in your microwave oven for up to 99 minutes 99 seconds.

21. STOP/CLEAR:

Touch this pad to stop the oven or to clear all entries.

22. START:

Touch this pad to start a function. If you open the door after oven begins to cook, START again.

23. LIGHT TIMER:

Touch this pad to set the light timer.

24. Ez-ON:

Touch this pad to set and start quickly at

100% power level.

25. LIGHT HI/LOW/OFF:

Touch this pad to turn on the cooktop/countertop light.

26. VENT ON/OFF:

Touch this pad to turn the fan on or off.

27. VENT CONTROL 5 SPEED:

Touch this pad to choose one of 5 fan speeds.

4-2

OVERALL CIRCUIT DIAGRAM

SCHEMATIC DIAGRAM (I)

*Check the Rating Model No.

MICOM CONTROLLER ASS’Y

L.V.

TRANS

FORMER

RY1

MAIN

RELAY

RY2

C/TOP

LAMP

HIGH

RELAY

RY3

C/TOP

LAMP

LOW

RELAY

RY5

VENT

FAN

ON/OFF

RELAY

SCR1

VENT

FAN

5 LVL

RY7

POWER

RELAY

CN1

1

OVEN

(

THERMOSTAT

)

BL

WH

AC

120V

60Hz

1 2 3

1’ 2’ 3’

GN

BK

FUSE

(20A)

RD

CONDENSER

RD

BK

5

6

7

3

4

10

11

8

9

12

YL

SECONDARY

SWITCH

WH

PK

WH

BL

O.L

BN

YL

YL

YL

F.M

BN

BL

BK

1’ 2’ 3’

1 2 3

4’

4

5’

5

6’

6

RD

HIGH

BK

V.M

BL

C

YL

C.L

2 1

2’ 1’

RD

BK

THERMOSTAT

BK

BK

(

M.G.T

PRIMARY

SWITCH

)

S.M

T.T.M

RD

RD

WH

MONITOR

SWITCH

RD

BK

1

CN3

2

3

RD WH

RC.

RS.

THERMISTOR

ABSOLUTE

HUMIDITY

SENSOR

WH

H.V.

CAPACITOR

H.V.DIODE

F

MAGNETRON

FA

* NOTE : DOOR IS OPENED.

O.L : OVEN LAMP

T.T.M :

F.M :

TURN TABLE MOTOR

FAN MOTOR

H.V.

TRANSFORMER

BL WH YL BN BK

CONTROL MODULE

PK BL WH RD BK

WIRE COLORS

12 PIN CONNECTOR(CN1)

5-1

3 PIN(CN3)

CONNECTOR

(FOR SENSOR)

SCHEMATIC DIAGRAM (II)

*Check the Rating Model No. (ADD Noise filter)

5-2

MATRIX CIRCUIT FOR TOUCH KEY BOARD

KEY MATRIX

5-3

GENERAL INFORMATION FOR SERVICE

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 glass turntable 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.

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

C. 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.

D. After about 5 minutes, make sure the primary interlock switch, the secondary interlock switch and the interlock monitor switch operate properly by opening and closing the door several times. Touch the START key each time the door is closed.

E. 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.

F. Confirm the water is hot.

G. Finally, measure the output power according to

“POWER OUTPUT MEASUREMENT” on page 7-3.

FEATURES AND SPECIFICATIONS

FEATURES

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

1000W 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 changes from one cooking stage to another.

This is made possible with the memory function of the microprocessor.

6-1

SERVICE INFORMATION

PRECAUTIONS AND REPAIR SERVICE TIPS

PRELIMINARY

A. SINCE NEARLY 4000 VOLTS EXISTS IN SOME

CIRCUITS OF THIS UNIT REPAIRS SHOULD BE

CARRIED OUT WITH GREAT CARE.

The filament leads of magnetron carry High

Voltage with respect to ground. Extreme caution must be exercised. Never plug the unit into a power source to determine which component is defective in high voltage section.

(3) Do not operate the unit until it is completely repaired, if any of the following conditions exist.

The unit must not be operated.

(a) The door does not close firmly.

(b) The hinge is broken.

(c) The door seal is damaged.

(d) The door is bent or warped, or there is any other visible damage on the unit that may cause microwave energy leakage.

NOTE:

Always keep the seal clean.

(e) Make sure that there are no defective parts in the interlock mechanism.

(f) Make sure that there are no detective parts in the microwave generating and transmission assembly (especially waveguide).

B. TO AVOID POSSIBLE EXPOSURE TO

MICROWAVE ENERGY LEAKAGE, THE

FOLLOWING PRECAUTIONS MUST BE TAKEN

BEFORE SERVICING.

(1) Before the power is applied:

(a) Make sure the primary interlock switch, the secondary interlock switch and the interlock monitor switch operate properly by opening and closing the door several by opening and closing the door several times.

(b) Make sure the perforated screen and the dielectric choke of the door are correctly and firmly mounted.

(4) The following items should be checked after the unit is repaired:

(a) The interlock monitor switch is connected correctly and firmly.

(b) The magnetron gasket is properly positioned and mounted.

(c) The waveguide and the oven cavity are intact.

(no microwave energy leakage)

(d) The door can be properly closed and the safety switches work properly.

(e) The unit must stop when the door is opened or the time is up.

(2) After power is applied:

(a) Make sure the interlock switch mechanism is operating properly by opening and closing the door.

(b) Check microwave energy leakage must be below the limit of 5 mW/cm 2 .

(All service adjustments should be made for minimum microwave energy leakage readings).

The unit must not be operated with any of the above components removed or by-passed.

7-1

MICROWAVE LEAKAGE TEST

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/cm 2

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.

• 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

• The service personnel should check all surface and vent openings for microwave emission testing.

• 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 2 .sq. And always start measuring of an unknown field to assure safety for operating personnel from radiation leakage.

NOTE:

The standard is 5mW/cm 2 .sq. while in the customer’s home.1mW/cm 2 .sq.stated here is manufacturer’s own voluntary standard for units in customer’s home.

EQUIPMENT-

• TESTER ((VOLTS-DC, AC, Ohmmeter)

• Microwave survey meter

- Holaday HI-1500

HI-1501

- Narda 8100

8200

• 600 cc non conductive material beaker (glass or plastic), inside diameter:approx.8.5 cm (3

1

/

2 in.)

• Glass thermometer: 100 °C or 212 °F (1 deg scale)

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 oven.

• 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 2-inch

(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. ( 1 in/sec)

7-2

MEASUREMENT WITH THE OUTER 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.

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 5 mW/cm 2 .

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 2

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.

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 1 mW/cm 2 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.

POWER OUTPUT MEASUREMENT

(1) 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 of potable water.

(2) The water is contained in a cylindrical borosilicate glass vessel having a maximum material thickness of

1

/

8

” (3 mm)and an outside diameter of approximately

7.6” (190mm).

(3) The oven and the empty vessel are at ambient

Temperature(T0)prior to the start of the test.

(4) The initial temperature (T1)of the water is

(10 ±1)°C (50 °F)It is measured immediately before the water is added to the vessel. After addition of the water to the vessel, the load is immediately placed on the center of the turntable which is in the lowest position and the microwave power switched on.

(5) The time t for the temperature of the water to rise by a value T of (10 ±1)°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.

(6) The microwave power output P in watts is calculated from the following formula :

7-3

4.187 Mw(T2 –T1)+0.55Mc(T2 –T0)

P = t is measured while the microwave generator is operating at full power. Magnetron filament heat-up time is not included. (about 3 sec)

(7) The water is stirred to equalize temperature throughout the vessel, prior to measuring the final water temperature.

(8) Stirring devices and measuring instruments are selected in order to minimize addition or removal of heat.

Where

P

is the microwave power output, in watts:

Mw

is the mass of the water, in grams:

Mc

is the mass of the container, in grams:

T0

is the ambient temperature, in °C:

T1

is the initial temperature of the water, in °C:

T2

is the final temperature of the water, in °C:

t

is the heating time in seconds, excluding the magnetron filament heat-up time.

WATER LOAD

GLASS TRAY

DISASSEMBLY INSTRUCTIONS

IMPORTANT NOTES:

UNIT MUST BE DISCONNECTED FROM ELEC-

TRICAL OUTLET WHEN MAKING REPAIRS, RE-

PLACEMENTS, ADJUSTMENTS AND CONTIN-

UITY CHECKS.

WHEN RECONNECTING THE WIRE LEADS TO

ANY PART, MAKE SURE THE WIRING CONNE-

CTIONS AND LEAD COLORS ARE CORRECTLY

MATCHED ACCORDING TO THE OVERALL CIR-

CUIT DIAGRAM. (ESPECIALLY SWITCHES AND

HIGH VOLTAGE CIRCUIT.)

A. REMOVING POWER AND CONTROL

CIRCUIT BOARD (Figures 1, 2 and 3)

(1) Remove a screw securing the control panel assembly to the oven cavity.

(2) Remove the control panel with pushing it upward.

(3) Remove the connectors (CN1, CN3) and wire leads (RY7) from the circuit board.

Control Panel

Screw

Circuit Board

Circuit Board

Figure 2

(5) Remove the FPC connector from the terminal socket following “HOW TO REMOVE THE FPC

CONNECTOR” on the next page.

(6) Remove the circuit board from the control bracket carefully.

(CN3)

(RY7)

Power Transformer

(CN1)

Figure 1

(4) Remove 5 screws securing the circuit board.

7-4

Control Bracket

FPC Connector(S1)

Circuit Board

Figure 3

HOW TO REMOVE THE F.P.C. CONNECTOR

Follow the steps below as illustrated in Figures 4 and 5 to remove the F.P.C. connector.

(1) Hold the edges of the plastic fastener with thumb and forefinger.

(Figure 4)

(2) Lift up the lever of the plastic fastener from the terminal socket by lightly pressing the lever end with forefinger.

(Figure 5)

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

HOW TO INSERT THE F.P.C. CONNECTOR

Follow the steps below as illustrated in Figures 6 and 7 to insert the F.P.C. connector.

(1) Insert the F.P.C. connector into the terminal socket securely with the fingers.

(2) Hold the plastic fastener with thumb and forefinger of the other hand, and push it slowly into the terminal socket. (Figure 6)

NOTE:

When reconnecting the F.P.C.

connector make sure that the holes on the F.P.C. connector are properly engaged with the hooks on the plastic fastener

(3) Lock the level of the plastic fastener into the hook of the terminal socket securely by releasing the fingers.

(Figure 7)

Plastic fastener

Holes

Plastic fastener

Hook

F.P.C.

Connector

Terminal socket

Figure 4

Holes

Plastic fastener

Hook

F.P.C.

Connector

Terminal socket

Figure 6

Plastic fastener

F.P.C.

Connector

Terminal socket

Figure 5

Terminal socket

Figure 7

7-5

B. REMOVING THE OUT CASE(Figure 8)

(1) Remove the vent grille by removing two screws securing it to the out case.

(2) Remove two screws securing it to the air duct.

(3) Remove the mounting plate by turning the screws

(1 or 2 screws)securing it to the out case.

(4) Remove two screws on the left central edge and one screw on the right central edge of Base plate.

Remove the Mount, All from the out case by removing one screw securing it to the out case.

(5) Remove six screws of the rear cavity.

(6) Remove the outcase.

Mount,All

Power cord cover

Door

Vent Grille

Figure 8

Controller

7-6

Mounting

Plate

Out Case

C. REMOVING THE DOOR INTERLOCK

SWITCHES (Figures 9, 10)

(1) Disconnect the wire leads from the interlock switches.

(2) Remove two screws securing the Latch Board.

(3) Make necessary replacements and check microwave energy leakage according to

“ADJUSTMENT PROCEDURES” on page 7-12.

Latch Board

Primary Interlock Switch

RD(from H.V.T)

RD(from Fan Motor)

BK(from Cooktop lamp)

BK(from MGT THERMOSTAT)

Monitor Interlock Switch

WH(from RY7)

RD(from Turntable Motor)

RD(from H.V.T)

Secondary Interlock Switch

PK(from P.C.B)

BL(from P.C.B)

Figure 9

Latch Board

Primary

Interlock Switch

Figure 10

WIRE COLOR

SYMBOL COLOR

WH WHITE

BK BLACK

BR BROWN

RD RED

YL YELLOW

PK PINK

BL BLUE

GY GREY

GN GREEN

N.P.

Not Provided

Monitor

Interlock Switch

Secondary

Interlock Switch

7-7

D. REMOVING MAGNETRON

(Figures 11 Through 12)

(1) Remove the vent grille by loosening two screws.

(Figure 11)

(2) Remove the outcase. See page 7-6.

(3) Remove four tap tite screws securing the magnetron to the wave guide.

(4) Disconnect the leadwire.

(5) Remove the magnetron VERY CAREFULLY.

NOTES:

• When removing the magnetron, make sure that its dome does not hit any adjacent parts, or it may be damaged.

• 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.

• After replacing the magnetron, check for microwave energy leakage with a survey meter Check microwave energy leakage must be below the limit of 5 mW/cm 2 . (All service adjustments should be made for minimum microwave energy leakage readings.) mount all

E. REMOVING STIRRER FAN

(Figures 13 and 14)

(1) Remove one rivet ASS'Y securing it to the oven upper plate by using knife blade.

(2) Remove the stirrer fan cover.

(3) Remove the stirrer fan.

Figure 13

vertgrille

Figure 11

Figure 14

Figure 12

Magnetron

7-8

F. REMOVING DOOR (Figure 15)

(1) Remove the vent grille by two screws securing it to the outcase loosening.

(2) Lift up and draw the door.

NOTES:

• After replacing the door, be sure to check that the primary interlock switch, the secondary interlock switch and the interlock monitor switch is in good operating normally.

• After replacing the door, check for microwave energy leakage with a survey meter. Microwave energy leakage must be below the limit of 5mW/cm 2 . (With a

275 ml water load)

H. ASSEMBLING DOOR

(1) 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 assemblyIf the door assembly is not mounted properly, microwaves may leak from the clearance between the door and the oven.

I. REMOVING THE VENTILATION FAN ASS'Y

(1) Remove the mounting plate by removing two screws securing it to the back plate.

(See Figure 17)

(2) Remove the two screws securing the MOUNT, ALL and one screw securing the ventilation fan ASS'Y.

(See Figure 18-a)

Figure 15

G. DISASSEMBLING DOOR (Figure 16)

(1) Remove the dielectric choke by using knifeblade or small screw driver, etc.

(2) Remove two screws securing it to the door handle.

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

Figure 17

Figure 16

Door Screen

7-9

Figure 18-a

MOUNT, ALL

(3) Carefully pull the ventilation motor ASS'Y out ofthe microwave oven. (See Figure 18-b)

Figure 18-b

J. REMOVING THE TURNTABLE MOTOR

(1) Remove the glass tray and rotating ring.

(2) Remove the turntable shaft VERY CAREFULLY with a hand. (Figure 19)

(3) Remove the base plate by removing 8 screws securing it to the oven cavity. (Figure 20)

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

(5) Remove the 1 screws securing the turntable motorto the oven cavity ASS'Y. (Figure 21)

NOTES:

• Remove the leadwire from the turntable motor

VERY CAREFULLY.

• Be sure to grasp the connector not the wires when removing.

Figure 19

7-10

Figure 20

Figure 21

Wire Leads

Turntable Motor

K. REPLACING THE HUMIDITY SENSOR

(1) Remove the sensor by removing two screws securing it to the air duct. (See Figure 22)

(2) Mount the new humidity sensor to the air duct.

Figure 22

7-11

INTERLOCK SYSTEM

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.

ADJUSTMENT PROCEDURES

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

CHECK THE DOOR LATCH AND SWITCH

CLOSING.

NOTE:

The outer cover of the microwave oven is removed.

The Interlock Monitor and Primary Interlock Switch act 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.

Mounting of the primary/monitor/secondary switches to the latch board.

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

Figure 23-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 23-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.

Latch Board

Primary

Interlock Switch

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”. Go to step 3 and follow all steps in order.

Interlock

Monitor Switch

Secondary

Interlock Switch

Figure 23-a

LATCH

ADJUST THE LATCH AND SWITCH CLOSING

(3) Loosen the two screws 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.

0-1/64"

LATCH BOARD

0-1/64"

Figure 23-b

7-12

TEST THE LATCH AND SWITCH SEQUENCE

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

Make sure the microwave energy leakage is below the limit of 1mW/cm 2 (with a 275 ml water load) and

5mW/cm 2 (with a 275 ml water load without the cabinet) when measured with a survey meter.

7-13

INTERLOCK CONTINUITY TEST

A. PRIMARY INTERLOCK SWITCH TEST

When the door is opened slowly, an audible

click

should be heard at the same time or successively at intervals and 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.

COMPONENTS

SWITCHES

(Wire leads removed)

TEST PROCEDURE

Check for continuity of the switch with an Ohm-meter

Primary

Switch

COM

NO

B. SECONDARY INTERLOCK SWITCH TEST

Disconnect the wire lead from the secondary switch.


(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.


(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.

Door open

RESULTS

Door closed

Monitor

Switch

COM

NC

Secondary

Switch

COM

NO

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

WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION

EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS.

TYPE NO.SZM-V16-FA-63 OR VP-533A-OF OR V-5230Q FOR PRIMARY SWITCH

TYPE NO.SZM-V16-FA-62 OR VP-532A-OF OR V-5220Q FOR MONITOR SWITCH

TYPE NO.SZM-V16-FA-63 OR VP-533A-OF OR V-5230Q FOR SECONDARY SWITCH

7-14

TEST AND CHECKOUT PRECEDURES 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 PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER.

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

TRANSFORMER

RESULTS

FILAMENT

WINDING

TEST

SECONDARY

WINDING

MAGNETRON

PRIMARY

WINDING

1. Remove wire leads.

2. Measure resistance. (ohm meter scale: Rx1)

• Primary winding

• Secondary winding

• Filament winding


• Primary winding to ground

• Filament winding to ground

Approx. 0.2 to 0.5 ohms

Approx. 50 to 120 ohms

0 ohm

Normal: Infinite

Normal: Infinite

Antenna

Gasket

Chassis

Filament

1. Remove wire leads. Install the magnetron seal in the correct position. Check that the seal is in good condition.


• Filament terminal


• Filament to chassis

Normal: Less than 1 ohm

Normal: Infinite

7-15

COMPONENTS

CAPACITOR

TEST RESULTS



• Terminal to terminal

• Terminal to case

Normal:

Momently indicates several ohm, and then gradually returns to infinite

Normal: Infinite.

DIODE

Some inexpensive ohm meters may indicate infinite resistance in both directions.

1. Measure continuity. Forward.

(ohm meter scale: Rx1000)

2. Measure continuity. Reverse.


Normal:Continuity.

Abnormal: Infinite.

Normal: Infinite.

Abnormal: Continuity.

RELAY 7

FAN MOTOR

1. Measure continuity.


2. Remove the lead wires and operate oven at power level 1 through power level 10.


2. Measure resistance.


C

B

A

Power

Level

7

8

5

6

3

4

1

2

9

10

Open

4 Sec

6 Sec

8 Sec

10 Sec

12 Sec

14 Sec

16 Sec

18 Sec

20 Sec

22 Sec

Close

18 Sec

16 Sec

14 Sec

12 Sec

10 Sec

8 Sec

6 Sec

4 Sec

2 Sec

0 Sec

Normal: Approximately

Abnormal:

Infinite or several.

7-16

COMPONENTS

VENTILATION MOTOR

1. Remove lead wires.


(ohm meter scale:Rx1)

TEST RESULTS

Normal:

Approximately 50 to 70 ohms

Abnormal:Infinite

TURNTABLE MOTOR




Normal: Approximately

2.5 to 3.5 Kohms

Abnormal:

Infinite or several.

ABSOLUTE HUMIDITY

SENSOR

(FOR SENSOR MODEL)

1. Disconnect sensor connector from micom computer board.

2. Measure resistance terminal to terminal (ohm meter scale: R X 1000)

Normal:

Approximately

BK-RD: 6.0 Kohms

RD-WH: 3.0 Kohms

BK-WH: 3.0 Kohms

Abnormal:

Infinite or approx. 0 ohm

STIRRER MOTOR

1

2

3

BK

RD

WH

1. Remove lead wires.


(ohm meter scale:Rx1000)

Normal:

Approximately 120 to 135 ohms

Abnormal:Infinite

7-17

COMPONENTS

TOUCH KEY BOARD

TEST RESULTS

Measure the resistance between terminal pins of connector KEY CONNECTOR.

NOTE:

When reconnecting the FPC connector, make sure that the holes on the FPC connector are properly engaged with hooks on the plastic fastener.

MATRIX CIRCUIT FOR

TOUCH KEY BOARD

CONNECTOR(KEY CON)

Resistance value

When touched

Less than

400 ohms

When not touched

More than

1 mega ohm

FPC CONNECTOR

Top

8

9

10

11

12

13

5

6

3

4

7

1

2

NOTES:

• A MICROWAVE ENERGY 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.

7-18

B. CHECKOUT PROCEDURES

(1) CHECKOUT PROCEDURES FOR FUSE BLOWING

CAUTION:

REPLACE BLOWN FUSE WITH 20 AMPERE FUSE.

PROBLEMS

Fuse blows immediately after the door is closed.

Fuse blows immediately after the door is opened.

CAUSES

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 high voltage transformer; the high voltage capacitor including the diode, the magnetron, the blower motor or the circuit board.

NOTES:

• If the fuse is blown by an improper switch operation, replace all 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 INTERLOCK ADJUSTMENT PROCEDURES on page

7-12 when the primary interlock, secondary interlock switches and/or the interlock monitor switches are adjusted or replaced.

7-19

(2)CHECKOUT PROCEDURES FOR RELAY.

-PROBLEM (A)-

FAN motor turns 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 YES

Replace the circuit board

Defective

Wire Assembly

-PROBLEM (A)--

Oven lamp turns 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 YES


Defective

Wire Assembly

Replace

Wire Assembly

-PROBLEM (B)-

FAN motor turns on When the door is closed and

START key is touched.

YES NO

GOOD

Measure the voltage at pin NO.

1,4 of CN1

Voltage reading:120 V AC

NO YES


Defective

FAN motor

Replace

Wire Assembly

-PROBLEM (B)-

Oven lamp turns on When the door is closed and

START key is touched.

YES NO

GOOD

Measure the voltage at pin NO.

1,4 of CN1

Voltage reading:120 V AC

NO YES


Defective

Oven lamp

Replace

FAN motor.

Replace

Oven lamp

7-20

(3) CHECKOUT PROCEDURES FOR CIRCUIT

BOARD

The following symptoms indicate a defective circuit board.

1) The start function fails to operate but the high voltage Systems, the interlock switches, the door sensing and the relay check good.

2) The unit with a normal relay continuously operates.

3) Proper temperature measurement is not obtained.

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.

8) Some of the indicators do no flicker 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.

7-21

7-22

7-23

7-24

7-25

#EV#

EXPLODED VIEW

DOOR PARTS

13581A

13213A

13536A

13720D

14890A

13552A

13650A

WTT028

14970A

14026A

13581A

13551A

13213A

13536A

13552A

13651A

13650A

-8-1-

WTT028

14970A

14026A

#EV#

CONTROLLER PARTS

268711

24781M

23572A

24810P

WTP018

* Check the

Rating Model No.

268712

* Check the


268711

MBM792

23506A

24810P

268711

WTP018

-8-2-

* Check the


268712

23551A

MBM792

24781M

* Check the


268711

#EV#

OVEN CAVITY PARTS

WTT027

WTT029

WTT028

34960A

33530A

34930R

35026G

33550L

36912C

WTT022

WTT010

35230A

-8-3-

34810Q

MFL552

33112U

MFL409

368771

63303A

63302A

66804A

WTT022

WTT010

34890C

34810T

#EV#

43501A

LATCH BOARD PARTS

43500A

466001

WSZ085

WSZ084

466003

466001

-8-4-

44510A

#EV#

INTERIOR PARTS (I)

33390G

34351A

35889A

WSZ002

54810A

56930M

WTP004

WTP002

56324A

WTT021

55238A

56170D

53300B

33740A

WTT021

36549S

WTT021

WTP013

WSZ002

56851D

54810C

50CZZH

-8-5-

WSZ002

#EV#

568773

INTERIOR PARTS (II - I)

Check the rating label of

Model

and order

SVC parts according to the

Model No.

36549V

56912B

WTT037

53550L

55231C

56549F

WTP005

* Check the


55262A

WTT028

50CZZM

56804A

* Check the


56411A

50FZZA

* Check the


55006F

56930V

55900A

56501A

WTP013

WSZ002

WTT024

* Check the


568771

56549B

55901A

53550F

340511

-8-6-

#EV#

INSTALLATION PARTS

63300M

WTT028

65862D

65862B

-8-8-

63861A

VINYL

BAG

No results