TECHNICAL FLASH

R

BASIC SERVICE MANUAL

FOR

MICROWAVE HOOD COMBINATION

MODEL 721. 64662 / 721. 64663

721. 64664 / 721. 64669

721. 80862 / 721. 80863

721. 80864 / 721. 80869

AUGUST, 2003

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.

MODEL 721. 64662 / 721. 64663

721. 64664 / 721. 64669

721. 80862 / 721. 80863

721. 80864 / 721. 80869

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

5-1

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 .......................................................................................................................... 7-11

INTERLOCK CONTINUITY TEST .......................................................................................................... 7-13

TEST AND CHECKOUT PROCEDURES AND TROUBLESHOOTING................................................. 7-14

A. TEST PROCEDURES................................................................................................................ 7-14

B. CHECKOUT PROCEDURES..................................................................................................... 7-16

C. TROUBLESHOOTING ............................................................................................................... 7-19

EXPLODED VIEW ..........................................................................................................................................

8-1

Rated Power Consumption

Microwave Output

Frequency

Power Supply

Rated Current

Magnetron Cooling

Rectification

Door Sealing

Safety Devices

Inverter

Magnetron

Cook top Lamp

Cavity Lamp

Timer

Tray

Overall Dimensions

Oven Cavity Size

Effective Capacity of Oven Cavity

Accessories

SPECIFICATIONS

1400W maximum (Microwave oven+Cook top lamps+Ventilation fan)

1200W (IEC 60705)

2,450 MHz ± 50 MHz

120 VAC, 60 Hz

12 Amp. (Microwave oven+Cook top lamps+Ventilation fan)

Forced Air Cooling

Rectification Voltage Double Half-Wave

Choke System

Thermostat:

Open at 110°C ± 5°C

Close at 0°C ± 5°C

Fuse(20A)

Primary Interlock Switch

Secondary Interlock Switch

Interlock Monitor Switch

P1-1019, 120 V

2M261

120 V, 20 W (Halogen)

125 V, 20 W (Halogen)

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

Tempered Safety Glass

29 15/16

”

(W)x16 7/16

”

(H)x15 3/8

”

(D)

23 1/2

”

(W)x10 3/16

”

(H)x14 1/2

”

(D)

2.0 Cu.ft.

Owner’s Manual & Cooking Guide, Installation Manual,

Exhaust Adapter, Exhaust Damper, Mounting Kit and Filter,

Rotating Ring Assembly, Glass Tray, Metal Rack, Defrost Plate.

SWITCH CHART

SWITCH MODE

CONDITIONS

PRIMARY

INTERLOCK

SWITCH

COM

NO

DOOR OPEN

DOOR CLOSED

NOTE

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

SECONDARY

INTERLOCK

SWITCH

COM

NO

INTERLOCK

MONITOR

SWITCH

COM

NC

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

FILAMENT

TERMINALS

MAGNETRON

MAGNETRON

CHASSIS GROUND

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

OPERATING INSTRUCTIONS

CONTROL PANEL

Your microwave oven control panel lets you select the desired cooking function quickly and easily. All you have to do is touch the necessary Command Button. The following is a list of all the Command and Number Buttons located on the control panel.

For more information on these features, see the “Using your microwave oven” section.

2 4 6 8 10 12 14 1

3

5 7

16 18 20

9 11 13 15

21 23

17 19 22 24 25

4-1

CONTROL PANEL INSTRUCTIONS

1. Display.

The display includes a clock and indicators to tell you time of day, cooking time settings, cook powers, quantities, weights, and cooking functions selected.

2. Popcorn.

Touch this button to pop popcorn with the sensor feature. 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 button to cook potatoes without entering a cook time or power.

4. Vegetable.

Touch this button to cook without entering a cook time or power.

5. Frozen Entree.

Touch this button to cook a 10- to 21ounce frozen entree without entering a cook time or power.

6. Auto Cook.

Touch this button to cook microwavable foods without entering a cook time or power.

7. Auto Reheat

. Touch this button to reheat microwavable foods without entering a cook time or power.

8. Sure Simmer.

Touch this pad to simmer soups, casseroles, stews, and other liquid foods.

9. Auto Defrost.

Touch this button followed by Number

Buttons to thaw frozen meat by weight.

10. Soften.

Touch this button to soften ice cream, cream cheese, butter, or frozen juice.

11. Melt.

Touch this button to melt chocolate, cheese, butter, or marshmallows.

12. Hold Warm.

Touch this button to keep hot, cooked foods safely warm in your oven for up to 99 minutes,

99 seconds. Hold Warm can be used by itself, or it can automatically follow a cooking cycle.

13. Add Minute.

Touch this button to cook for 1 minute at

100% cook power, or to add extra minutes at the set cook power to your cooking cycle.

14. More.

Touch this button to add 10 seconds of cook time each time you press it.

15. Less.

Touch this button to subtract 10 seconds of cook time each time you press it.

16. Clock.

Touch this button to enter the time of day.

17. Timer.

Touch this button to change the oven’s default settings for Kitchen Timer, Light Timer SET or CLEAR.

18. Cook Time.

Touch this button followed by Number

Buttons to set a cooking time.

19. Power.

Touch this button after the cook time has been set, followed by a Number Button to set the amount of microwave energy released to cook the food. The higher the number, the higher the microwave power or

“cooking speed.”

20. Number Buttons.

Touch number buttons to enter cooking times, cook powers, quantities, weights, or food categories.

21. START.

Touch this button to start a function. If you open the door after the oven begins to cook, retouch

START.

22. STOP/Clear.

Touch this button to erase an incorrect command, cancel a program during cooking, or to clear the Display.

23. Fan ( ) On/Off.

Touch this button to turn the fan on or off.

24. Fan ( ) 5-Speed.

Touch this button to choose one of

5 fan speeds.

25. Light ( ).

Touch this button to turn the light on high, night, or off.

NOTE: If you try to enter

incorrect instructions, you will not hear any tones. Touch STOP/CLEAR and re-enter the instructions.

4-2

OVERALL CIRCUIT DIAGRAM

SCHEMATIC DIAGRAM

5-1

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

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 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.

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.

(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).

(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).

(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.

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.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

• 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 :

P =

4,187 Mw(T2 –T1)+0.55Mc(T2 –T0) t is measured while the microwave generator is operating at full power. Magnetron filament heat-up time is not included. (about 5 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

7-3

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.)

(4) Remove 3 screws securing the circuit board.

Circuit Board

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), and sensor (CN5) wire leads (RY2, CN2, CN4) from the circuit board.

Control Panel

Screw

(CN4)

Circuit Board

Figure 2

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

Power

Transformer

(CN5)

(CN6)

(CN7)

Control Bracket

(CN2)

(CN1)

Circuit Board

Figure 1

Figure 3

7-4

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 two screws 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 four screws of the rear cavity.

(6) Remove the outcase with disconnecting power cord connector.

Door

Vent Grille

Controller

Figure 8

7-5

Mount, All

Power code

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 7-11.

Latch Board

Primary Interlock Switch

WH(from Inverter)

YL(from Turntable Motor)

PK(from Cooktop lamp)

BL(from Oven Thermostat)

Latch Board

Primary

Interlock Switch

Monitor Interlock Switch

WH(from Inverter)

RD(from Inverter)

Secondary Interlock Switch

PK(from P.C.B)

BL(from P.C.B)

Figure 9

Figure 10

WIRE COLOR

SYMBOL COLOR

WH WHITE

BK

BR

BLACK

BROWN

RD

RED

YL

PK

BL

GY

YELLOW

PINK

BLUE

GREY

GN GREEN

N.P.

Not Provided

7-6

Interlock

Monitor Switch

Secondary

Interlock Switch

D. REMOVING MAGNETRON

(Figures 11 Through 12)

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

(Figure 11)

(2) Remove the outcase. See page 7-5.

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

(4) 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 THE INVERTER MODULE

(Figures 13 Through 15)

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

(Figure 11)

(2) Remove the outcase. See page 7-5.

(3) Remove the base plate by loosening four screws.

(Figure 13)

(4) Disconnect two leadwire of the fan motor assembly.

(5) Disconnect the leadwire of the inverter PCB and

H.V. cable of the magnetron.

(6) Remove the earth wire screw.

(7) Remove three screws securing to duct assembly and two screws securing to fan guide. (Figure 14)

(8) Remove the screw securing to inverter module assembly.

(9) Push the inverter guide hook and out the inverter module assembly lifting up duct assembly.

(10) Open the upper inverter guide.

(11) Remove three screws securing to PCB and pull out PCB. (Figure 15)

Figure 13

Figure 11

Figure 12

7-7

Figure 14

Figure 15

Front

Back

Front

F. REMOVING STIRRER FAN

(Figures 16 and 17)

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

(2) Pull out the stirrer fan cover.

(3) Remove two rivets ASS'Y securiting it to the oven upper plate by using knife blade.

(4) Remove the stirrer fan.

G. REMOVING DOOR (Figure 18)

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

(2) Disconnect two leadwires.

(3) 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)

Figure 16

Figure 18

H. DISASSEMBLING DOOR (Figure 19)

(1) Remove the dielectric choke by using knife blade 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 19

Door Screen

7-8

I. 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 assembly. If the door assembly is not mounted properly, microwaves may leak from the clearance between the door and the oven.

Space

(3) Carefully pull the ventilation motor ASS'Y out of the microwave oven. (See Figure 21-b)

Figure 21-b

J. REMOVING THE VENTILATION MOTOR

(1) Remove the mounting plate by loosening mounting plate screws (1 or 2 screws) securing it to the back plate.

(See Figure 20)

(2) Remove MOUNT ALL loosening one screw loosening one screw securing the ventilation Motor and back plate. (See Figure 21-a)

Figure 20

Figure 21-a

Mount , All

7-9

K. REMOVING THE TURNTABLE MOTOR

(1) Remove the glass tray and rotating ring.

(2) Remove the turntable shaft VERY CAREFULLY with a hand. (Figure 22)

(3) Remove the base plate by removing 8 screws securing it to the oven cavity. (Figure 23)

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

(5) Remove the 1 screws securing the turntable motor to the oven cavity ASS'Y. (Figure 24)

NOTES:

•

Remove the leadwire from the turntable motor

VERY CAREFULLY.

•

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

Figure 22

Figure 23

Wire Leads

Turntable Motor

Figure 24

7-10

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 25-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 25-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

Interlock

Monitor Switch

Secondary

Interlock Switch

Figure 25-a

LATCH

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.

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 25-b

7-11

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.

7-12

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)

Check for continuity of the switch with an Ohm-meter

Primary

Switch

TEST PROCEDURE

COM

NO

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.

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.

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

7-13

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 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

7-14

COMPONENTS

SENSOR

TEST PROCEDURE RESULTS

Antenna

Gasket

Chassis

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: 5.6 Kohms

RD-WH: 2.8 Kohms

BK-WH: 2.8 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.

7-15

COMPONENTS

FAN MOTOR

(Wire leads removed)

TEST PROCEDURE

Measure the resistance.

(Ohm-meter scale: R x 100)

B(BK)

A(RD)

C(WH)

RESULTS

Normal: Approx. 50 ~ 150 ohms

Abnormal: Infinite or several ohms.

A-B: 76 ohms

B-C: 22 ohms

A-C: 96 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.

STIRRER MOTOR

(Wire leads removed)

Measure the resistance.

(Ohm meter scale: Rx100)

Normal: Approx. 125 to 135 ohms

Abnormal: Infinite or several ohms.

Check for continuity of relay 2 with an ohm-meter.

(Remove wire leads from relay 2 and operate the unit.)

Relay 2

Normal:

ON: 0 ohm

OFF: Infinite ohms

Abnormal: Infinite or several ohms.

RELAY2

7-16

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.

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

7-11 when the primary interlock, secondary interlock switches and/or the interlock monitor switches are adjusted or replaced.

7-17

(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

Replace the circuit board

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, 5 of CN1

Voltage reading: 120 V AC

NO YES

Replace the circuit board

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

Replace the circuit board

Defective

Oven lamp

Replace

FAN motor.

Replace

Oven lamp

7-18

(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 high voltage Systems, 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.

8) 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.

7-19

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 the inverter, disconnect lead wires 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.

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.

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.

REMEDY

Avoid using other electrical appliances when you use the microwave oven.

Insert microwave oven plug securely.

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.

7-20

(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 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 door

PCB assembly.

Replace key membrane assembly and check operation.

RESULT

Continuity

No continuity

Everything works as specified.

Still have trouble.

CAUSE

Defective door

PCB assembly.

Loose connection.

Defective key membrane assembly.

Defective door

PCB assembly.

REMEDY

Replace door PCB assembly.

Connect them tightly.

Replace key membrane assembly.

Replace door PCB assembly.

7-21

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

RESULT CONDITION

1. Fuse blows.

CHECK

Check continuity of monitor switch (with door closed).

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

P.C.B Assembly.

Replace fuse, primary, monitor switches, and

P.C.B Assembly.

Disconnect one side of the lead wires connected from Inverter.

Normal.

Fuse blows again

Defective door or control PCB.

Defective Inverter.

Replace door or control PCB.

Replace Inverter.

2. Fuse does not blow.

Check continuity of thermostat.

No continuity.

Continuity.

Check continuity of power supply cord.

No continuity.

Defective thermostat.

Defective power supply cord.

Replace thermostat.

Replace power supply cord.

7-22

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

RESULT CONDITION

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

CHECK

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 control PCB assembly.

Check fan motor.

Check oven lamp.

Continuity

No continuity

Abnormal

Abnormal

Normal

Defective control

PCB assembly.

Loose connection.

Defective fan motor.

Defective oven lamp.

REMEDY

Replace secondary switch.

Replace control

PCB assembly.

Connect them tightly.

Replace fan motor.

Replace oven lamp.

3. The display shows F-9.

Loose connection.

Connect them tightly.

Check the connection between magnetron, door & control PCB and inverter module.

Check the Relay 2 of control PCB assembly.

No continuity.

Continuity.

Check the inverter module.

Check the

Magnetron.

Check the power source voltage.

Abnormal

Normal

Abnormal

Normal

Abnormal

Normal

Abnormal

7-23

Defective Relay2.

Defective inverter module.

Defective

Magnetron.

Unsafe AC input voltage.

Replace control

PCB assembly.

Replace inverter module.

Replace

Magnetron.

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

CONDITION

4. The display shows F-4.

CHECK

Check the connection between sensor wire and control PCB.

RESULT

Abnormal

Normal

CAUSE

Loose connection.

REMEDY

Connect them tightly.

Check the sensor.

Abnormal

Normal

Defective sensor.

Defective door or control PCB assembly.

Replace sensor.

Replace door or control PCB assembly.

(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.

7-24

#EV#

EXPLODED VIEW

DOOR PARTS

MODEL:

721. 64662 / 721. 64663

721. 64664 / 721. 64669

721. 80862 / 721. 80863

721. 80864 / 721. 80869

1004

1002

1005

1000

FOR 64663 ONLY

80863

1381

1003

1008

W171

W109

1015

1011

W109

1007

1006

1009

8-1

#EV#

1001

2016

CONTROLLER PARTS (I)

W171

2009

W171

2007

2017

8-2

#EV#

2004

CONTROLLER PARTS (II)

2002

2008

FOR 64663 ONLY

80863

2381

2006

W106

8-3

#EV#

3024

OVEN CAVITY PARTS

FOR 64662/64664

80862/80864

FOR 64669/64663

80869/80863

W138

W142

W108

3010

W138

W142

W138

W142

3031

W109

3018

3036

3033

W149

5036

3026

8-4

3029

3001

W121

3003

3005

3043

W150

3032

5382

W149

6000

#EV#

4001

W102

LATCH BOARD PARTS

4000

4002

4003

4002

4004

8-5

#EV#

5024

3054

3008

3017

3002

INTERIOR PARTS (I)

5026

W109

W130

5049

W101

W109

5025

W146

W109

5012

5057

5003

W109

5052

W109

5009

W101

5000

3009

W105

5044

W109

5066

5048

3007

5035

W109

W109

3004

8-6

#EV#

INTERIOR PARTS (II)

5015

5045

W150

W150

5027

5011

W144

5056

5006

5016

5029

5037

3027

W144

W109

5001

5041

5019

5065

5064

5010

5014

8-7

#EV#

INSTALLATION PARTS

6009

6008

6011

6010

8-8

P/NO : 3828W5S3335 Printed in Korea