Kenmore 721.62222, 721.62229, 721.62229301, 721.62222301 Service Manual

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MODEL 721.62222

721.62229

DIVISION 20

BASIC FIELD MANUAL

FOR

MICROWAVE OVEN

MODEL 721.62222300 / 721.62222301

721.62229300 / 721.62229301

May, 2005

CAUTION

WARNING TO SERVICE TECHNICIANS

PRECAUTIONS TO BE OBSERVED BEFORE

AND DURING SERVICING TO AVOID

POSSIBLE EXPOSURE TO EXCESSIVE

MICROWAVE ENERGY

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

b. Make the following safety checks on all ovens to be serviced before activating the magnetron or other

microwave source, and make repairs as necessary; (1) Interlock operation, (2) proper door closing, (3)
seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or loosening of hinges and
latches, (5) evidence of dropping or abuse.

c. Before turning on microwave for any service test or inspection within the microwave generating

compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment,
integrity, and connections.

d. Any defective or misadjusted components in the interlock, monitor, door seal, and microwave

generation and transmission systems shall be repaired, repaired 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.

-1-

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 721.62222

721.62229

MECHANICAL SERVICE INFORMATION

TABLE OF CONTENTS

1. Adjustment Procedures .....................................................................................................................................3

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

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

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

5. Specifications ....................................................................................................................................................6

6. Overall Circuit Diagram .....................................................................................................................................7-9

7. Operating Procedures .......................................................................................................................................10-12

8. Procedure for Measuring Microwave Energy Leakage .....................................................................................13-14

9. Disassembly Instructions ..................................................................................................................................15-19

10. Interlock Continuity Test ..................................................................................................................................20

11. Test and Checkout Procedures, and Troubleshooting

A. Test Procedures .........................................................................................................................................21-23

B. Checkout Procedures .................................................................................................................................24-26

C. Troubleshooting ..........................................................................................................................................27-31

12. Exploded View ................................................................................................................................................32-39

13. Part Reference list ..........................................................................................................................................40-43

-2-

1. ADJUSTMENT PROCEDURES

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

ADJUST THE LATCH AND SWITCH CLOSING

(3) Loosen the two screws holding the plastic latch board as

shown.

ONLY AUTHORIZED SERVICE PERSONNEL
SHOULD MAKE THIS ADJUSTMENT.

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. See Figures 1-a
and 1-b throughout this procedure.

CHECK THE DOOR LATCH AND SWITCH
CLOSING.

NOTE: The outer cover of the microwave oven is

removed.

(1) Set the microwave oven on its side so that you can see

the latch board and the switches, as shown in
Figure 1-a.

(2) Close the door tightly and check gaps A and B to be

sure they are no more than 1/64” (0.5 mm). See Figure
1-b for close-up view of gaps A and B (door latches).
If all gaps are less than 1/64” (0.5 mm), adjustment of
the latch board may not be necessary. Go to Steps 5
and 6 to check the sequence of the switches.

NOTE: To correct sequence of the Primary Interlock

Switch, Secondary Interlock Switch and the
Interlock Monitor Switch are very important.

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

(4) With the oven door closed tightly, move the latch board

upward toward the top of the oven and/or away from the
door latch until the gaps are less than 1/64” (0.5 mm).

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

TEST THE LATCH AND SWITCH SEQUENCE

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

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

- Primary Interlock Switch

- Secondary Interlock Switch

- Interlock Monitor Switch

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

(6) Close the oven door slowly and be sure it is tightly

closed. Watch the three switches to make sure they are
zero to the body of the switches in the following
sequence:

- Interlock Monitor Switch

- Primary Interlock Switch

- Secondary Interlock Switch

NOTE: The Interlock Monitor Switch is an added safety

check on the Primary and Secondary Interlock
Switches. If the Primary and Secondary Interlock
Switches allow the oven to operate with the door
open, the Monitor Switch will blow the fuse.

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

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

TEST THE MICROWAVE ENERGY LEAKAGE

(8) Using a survey meter, make sure the microwave energy

is below 5 mW/cm.sq.

-3-

LATCH BOARD

MONITOR
INTERLOCK
SWITCH

PRIMARY
INTERLOCK
SWITCH

SECONDARY
INTERLOCK
SWITCH

LATCH

LATCH BOARD

0-1/64"

0-1/64"

A

B

DOOR LATCH

Figure 1-a

Figure 1-b

-4-

2. PRECAUTIONS ON INSTALLATION

(Figure 2)

A. Plug the power supply cord into a 120 V AC, 60 Hz,

single-phase power source with a capacity of at least 20
amperes.

B. Since the unit weights about 38 lbs, be sure to place it

on a sturdy and flat surface.

C. Avoid placing the unit in a location where there is direct

heat or splashing water.

D. Place the unit as far away as possible from TV, radio,

etc. to prevent interference.

CAUTION

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

Properly Polarized and
Grounded
Outlet

4. TRIAL OPERATION

After installation, the following sequences and results
should be checked carefully.
A. Put a container filled with water (about 1 liter) into the

oven, and close the door tightly.
B. Touch the STOP/CLEAR and the COOK TIME keys.
C. Set cooking time for 10 minutes by touching “1”

and then “0” three times. “1000” appears in the

display window.
D. Touch the START key.

Make sure the cavity light comes on. The unit will begin

cooking and the display window will show the time

counting down by seconds.
E. After about 5 minutes, make sure the primary interlock

switch, the secondary interlock switch and the interlock

monitor and oven lamp switch operate properly by

opening and closing the door several times. Touch the

START key each time the door is closed.
F. Continue operating the unit. Four long beep sound signal

is heard when the time is up. The unit will shut off

automatically.
G. Confirm the water is hot.
H. Finally, measure the output power according to “POWER

OUTPUT MEASUREMENT” on page 13.

Three-Pronged(Grounding)
Plug

Figure 2

3. GENERAL PRECAUTIONS IN USE

A. Never operate the unit when it is empty. Operating the

oven with no load may shorten the life of the magnetron.
Whenever cooking dry foods (dried fish, bread, etc.) or a
small amount of food, be sure to put a glass of water into
the cooking compartment. The turntable tray may
become hot after operating, be careful when touching it.

B. Aluminum foil should be avoided because it will disrupt

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

5. FEATURES AND SPECIFICATIONS

A. The safety systems incorporated in this model are:

(1) Primary interlock switch
(2) Secondary interlock switch
(3) Interlock monitor switch
(4) Choke system
(5) Magnetron thermostat
(6) 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 100W 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 can be set. The oven

remembers three cooking stages and changes from one

cooking stage to another. This is made possible with the

memory function of the microprocessor.

-5-

SPECIFICATIONS

Rated Power Consumption ................................... 1400W maximum

Output ................................................................... 1000W maximum (*IEC 60705 Rating standard)

Adjustable 100W through 1000W, 10steps

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

Power Supply......................................................... 120V AC, 60Hz

Rated Current ....................................................... 12.3 Amp.

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

Microwave Stirring ................................................ Turntable

Rectification ........................................................... Rectification Voltage Doubler Half-Wave

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

Safety Devices ...................................................... Thermostat:

Open at 90°C ± 5°C

Close at 75°C ± 5°C
Fuse (20A)
Primary Interlock Switch
Secondary Interlock Switch
Interlock Monitor

Magnetron ............................................................. 2M246 - 050GF

High Voltage Capacitor ......................................... Capacitor: 0.95µF, 2.1KV Ac

High Voltage Diode ............................................... 350mA, 9.0KV

Cavity Lamp .......................................................... 125V, 20W

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

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

1

Overall Dimensions ............................................... 20

Oven Cavity Size .................................................. 137/

Effective Capacity of Oven Cavity ......................... 1.1 Cu.ft.

Accessories .......................................................... Use and Care Manual, Turntable,

/8”(W) x 12”(H) x 151/8”(D)

5

8”(W) x 9

/

16”(H) x 14

Rotating Ring Assembly.

3

/

16”(D)

SWITCH CHART

PRIMARY

SWITCH MODE

INTERLOCK

SWITCH

CONDITIONS

DOOR OPEN
DOOR CLOSED

COM

NO

∞∞0

00∞

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

-6-

SECONDARY

INTERLOCK

SWITCH

COM

NO

INTERLOCK

MONITOR

SWITCH

COM

NC

6. OVERALL CIRCUIT DIAGRAM

A (I). SCHEMATIC DIAGRAM *Check the Model No.

-7-

A (II). SCHEMATIC DIAGRAM *Check the Model No. (ADD Noise filter)

-8-

B. MATRIX CIRCUIT FOR TOUCH KEY BOARD

Figure 4

-9-

7. OPERATING PROCEDURES

Figure 5

1

7
8

10

9

11

4

5

6

2

3

A. OVEN CONTROL PANEL

NOTE: A "beep" sounds when you touch a "key" on the control panel,

to indicate that you have entered a setting.

-10-

B. PANEL INSTRUCTIONS

The entire operation is done by simple touch control pads.

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

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

3. AUTO DEFROST. This pad is an accurate defrosting
method for frozen meat, poultry and fish up to 6.0 lbs
or 4.0 kgs.

4. NUMBER PADS. Touch Number Pads to enter cooking
time, power level, quantities, or weights.

5. COOK TIME. Touch this pad to set a cooking time.

6. STOP/CLEAR. Touch this pad to stop the oven or clear

entries.

7. KITCHEN TIMER. Touch this pad to use your
microwave oven as a kitchen timer.

8. CLOCK. Touch this pad to enter the time of day.

9. POWER. Touch this pad to set a cooking power.

10. ADD MINUTE. Touch this pad to cook at 100% cook

power for 1 minute to 99 minute 59 seconds.

11. START. Touch this pad to start all entries (except the

Quick Touch Sensor, Express Defrost, Auto Cook and
Add Minute function which start automatically) and to
turn Child Lock on or off.

-11-

C. EASY USE CHART

(1) CLOCK

1. Touch STOP/CLEAR.

2. Touch CLOCK.

3. Touch numbers for correct time of day.

4. Touch START.

(2) KITCHEN TIMER

1. Touch STOP/CLEAR.

2. Touch KITCHEN TIMER.

3. Touch correct numbers for time.

4. Touch START.

(3) CHILD LOCK

To set:

1. Touch STOP/CLEAR.

2. Touch “START” more than 4 seconds.
To cancel:

1. Touch STOP/CLEAR.

2. Touch “START” more than 4 seconds.

(4) ADD MINUTE

1. Touch STOP/CLEAR.

2. Touch ADD MINUTE.

(7) QUICK TOUCH SENSOR COOKING

1. Touch STOP/CLEAR.

2. Touch POPCORN.

(8) AUTO DEFROST

1. Touch STOP/CLEAR.

2. Touch AUTO DEFROST.
Three different defrosting levels are provided.
(MEAT, POULTRY, FISH)

3. Enter the weight of your food in decimal
increments from 0.1 to 6.0 pounds.

4. Touch START

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

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

(5) TIMED COOKING

1. Touch STOP/CLEAR.

2. Touch COOK TIME.

3. Touch numbers for cooking time.

4. Touch POWER.

5. Touch number for cooking power level.

6. Touch START.

(6) MULTI-STAGE COOKING

1. Touch STOP/CLEAR.

2. Touch COOK TIME.

3. Touch numbers for cooking time.

4. Touch POWER.

5. Touch number for cooking power level.

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

7. Touch START.

-12-

8. PROCEDURE FOR MEASURING MICROWAVE

Figure 7

ENERGY LEAKAGE

A. CAUTIONS

(1) Be sure to check a microwave emission prior to servicing

the oven if the oven is operative prior to servicing.

(2) The service personnel should inform the manufacturer,

importer, or assembler of any certified oven unit found to
have a microwave emission level in excess of
5mW/cm.sq. and should repair any unit found to have
excessive emission levels at no cost to the owner and
should ascertain the cause of the excessive leakage.
The service personnel should instruct the owner not to
use the unit until the oven has been brought into
compliance.

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

personnel should;

- Tell the user not to operate the oven

- Contact the manufacturer and CDRH (Center for
Devices and Radiological Health) immediately.
NOTE: Address on CDRH
Office of Compliance (HFZ-312)
Center for Devices and Radiological Health
1390 Piccard Drive
Rockville, Maryland 20850

(4) The service personnel should check all surface and vent

openings for microwave emission testing.

(5) Check for microwave energy leakage after every

servicing. The power density of the microwave radiation
leakage emitted by the microwave oven should not
exceed 1mW/cm.sq. And always start measuring of an
unknown field to assure safety for operating personnel
from radiation leakage.
NOTE: The standard is 5mW/cm.sq. while in the
customer’s home. 1mW/cm.sq. stated here is
manufacturer’s own voluntary standard for units in
customer’s home.

EQUIPMENT

• Electromagnetic energy leakage monitor (NARDA 8100B,
HOLADAY HI 1501)

• 600cc glass beaker

• Glass thermometer 100°C

B. MEASURING MICROWAVE ENERGY LEAKAGE

(1) Pour 275±15cc of 20±5°C water in a beaker which is

graduated to 600 cc, and place the beaker in the center
of the oven.

(2) Set the energy leakage monitor to 2,450 MHz and use it

following the manufacturer’s recommended test
procedure to assure correct result.

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

(5cm) spacer supplied with the probe.
(4) Operate the oven at its maximum output.
(5) Measure the microwave radiation using and

electromagnetic radiation monitor by holding the probe

perpendicular to the surface being measured. (See

Figure 7)

Move probe along shaded area.

Probe scanning speed
less than 2.5 cm/sec.

C. 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.

Figure 6

-13-

D. MEASUREMENT WITH A FULLY ASSEMBLED OVEN

(1) After all components, including the outer panels, are

fully assembled, measure for microwave energy
leakage around the door viewing window, the exhaust
opening and air inlet openings.

(2) Microwave energy leakage must not exceed the values

prescribed below.

NOTES:

Leakage with the outer panels removed - less than
5mW/cm.sq. Leakage for a fully assembled oven
(Before the latch switch (primary) is interrupted) with the
door in a slightly opened position - less than
1 mW/cm.sq.

E. NOTE WHEN MEASURING

(1) Do not exceed meter full scale deflection.
(2) The test probe must be removed no faster than 1

inch/sec (2.5cm/sec) along the shaded area, otherwise
a false reading may result.

(3) The test probe must be held with the grip portion of the

handle. A false reading may result if the operator’s
hand is between the handle and the probe.

(4) When testing near a corner of the door, keep the probe

perpendicular to the surface making sure the probe
horizontally along the oven surface, this may possibly
cause probe damage.

G. POWER OUTPUT MEASUREMENT

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

water.

(2) Stir the water in the beaker with thermometer (°F or °C)

and measure temperature as T1.
(3) Place the beaker on the center of turntable.
(4) Set for one (1) minute and three (3) seconds and operate

the oven at high power.

NOTE: The additional three (3) seconds is to allow the

magnetron to begin generating power.

(5) When the heating is finished, stir the water again with

thermometer and measure the temperature of water as T2.
(6) Subtract T1 from T2, this will give you the temperature rise.
(7) The microwave power output is within specification, if the

temperature rise is as shown below:

Temperature Rise

Line Voltage

120 V
108 V

(8) Power output will be influenced by line voltage of power

supply. Consequently, correct power output must be

measured within 120V AC ± 1 Volt while unit is operating.

Degrees°F

18.9 ~ 25.2
Min. 17.5

Degrees°C

10.5 ~ 14
Min 9.7

SPECIAL TIP

F. RECORD KEEPING AND NOTIFICATION AFTER

MEASUREMENT

(1) After adjustment and repair of any microwave energy

interruption or microwave energy blocking device,
record the measured values for future reference. Also
enter the information on the service invoice.

(2) Should the microwave energy leakage not be more

than 1mW/cm.sq. after determining that all parts are in
good condition, functioning properly and genuine
replacement parts which are listed in this manual have
been used.

(3) At least once a year, have the electromagnetic energy

leakage monitor checked for calibration by its
manufacturer.

• This oven used the button head screws.

Button Head

(Torx style 2)

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

-14-

9. DISASSEMBLY INSTRUCTIONS

Figure 8

Figures 9

F.P.C.Connector

Control Panel

Circuit Board

securing screw

IMPORTANT NOTES:

UNIT MUST BE DISCONNECTED FROM ELECTRICAL
OUTLET WHEN MAKING REPAIRS, RE-PLACEMENTS,
ADJUSTMENTS AND CONTINUITY CHECKS. WAIT AT
LEAST ONE MINUTE, UNTIL THE HIGH VOLTAGE
CAPACITOR IN THE HIGH VOLTAGE POWER
SUPPLY HAS FULLY DISCHARGED. THE CAPACITOR
SHOULD BE DISCHARGED BY USING INSULATED
WIRE - I.E. TEST PROBE CONNECTED TO 10KOHM
RESISTOR IN SERIES TO GROUND. WHEN
RECONNECTING THE WIRE LEADS TO ANY PART,
MAKE SURE THE WIRING CONNECTIONS AND LEAD
COLORS ARE CORRECTLY MATCHED ACCORDING
TO THE OVERALL CIRCUIT DIAGRAM. (ESPECIALLY
SWITCHES AND HIGH VOLTAGE CIRCUIT.)

A. REMOVING OUT CASE (Figures 8)

(1) Remove three screws from the rear section.
(2) Remove one screw from the side section.
(3) Push the outer case back about 1 inch (3cm).
(4) Lift the case from the set.

(7) Pull down and remove the circuit board from the control

panel.

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

Remove screw

Lift up and pull out control panel

B. REMOVING POWER AND CONTROL CIRCUIT

BOARD(Figure 9)

(1) Open the door.
(2) Remove one screw from the cavity.
(3) Disconnect the lead wire from RELAY(RY2) on the

circuit board.

(4) Lift up and pull out control panel assembly carefully

from the cavity.

(5) Disconnect the lead wire from connector(CN1) on the

circuit board.

(6) Remove two screws, securing the circuit board.

CAUTION: DISCHARGE THE HIGH VOLTAGE

CAPACITOR BEFORE SERVICING.

-15-

Door seal plate

Figure 10

C. DOOR GROSS ASSEMBLY REMOVAL

(1) Open the door.
(2) Remove the choke cover cap very carefully with a flat-blade

screwdriver.

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

screwdriver.

(3) Lift up and pull out the door.

NOTE:

1. After replacing the door, be sure to check that the primary
switch, monitor switch, and secondary switch operate
normally.

2. After replacing the door, check for microwave energy leakage
with a survey meter. Microwave energy must be below the
limit of 5 mW/cm.sq. (with a 275 ml water load)

3. When mounting the door assembly to the oven assembly, be
sure to adjust the door assembly parallel to the chassis. Also
adjust so the door has no play between the inner door surface
and oven frame assembly. If the door assembly is not
mounted properly, microwaves may leak from the clearance
between the door and the oven.

Remove choke cover cap

Remove door

-16-

D. MAGNETRON REMOVAL

Magnetron

Waveguide

Magnetron
Gasket

Magnetron

Dome

Waveguide
Bracket

Figures 11

(1) Disconnect the wire lead from the magnetron.
(2) Carefully remove the mounting screws holding the

magnetron and the waveguide.

(3) Remove the magnetron assembly until the tube is clear

from the waveguide.

NOTE:

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

2. When replacing the magnetron, be sure to install the
magnetron gasket in the correct position and be sure
that the gasket is in good condition.

3. After replacing the magnetron, check for microwave
leakage with a survey meter around the magnetron.
Microwave energy must be below the limit of 5 mW/cm2.
(With a 275 ml. water load).

Make sure that gasket is rigidly attached to the

magnetron. To prevent microwave leakage, tighten the
mounting screws properly, making sure there is no gap
between the waveguide and the magnetron.

E. SUCTION GUIDE MAIN ASSEMBLY
NOTE: To repair any of them, the Suction Guide Main ASS’Y

should be removed first.
(1) Disconnect the wire lead from the capacitor and fan motor.
(2) Remove two screws holding the Suction Guide Main ASS’Y

to oven cavity.

(3) Pull out Suction Guide Main ASS’Y from the oven.

Remove screw

Screw

Pull out suction guide main ASS’Y

Pull out

Figures 12

-17-

F. FAN MOTOR ASSEMBLY REMOVAL

Suction
Guide

H.V.
Diode

H.V.
Capacitor

Figures 14

NOTE: To repair any of them, the Suction Guide Main ASS’Y

should be removed first.
(1) Disconnect the wire lead from the fan motor.
(2) Remove the fan.
(3) Remove the two screws holding the fan motor assembly to

the suction guide ass’y.

G. HIGH VOLTAGE TRANSFORMER REMOVAL

(1) Discharge the high voltage capacitor.
(2) Disconnect the wire lead from the magnetron, the high

voltage transformer, and the capacitor.

(3) Remove the screw holding the high voltage transformer to

the base-plate.

Figures 15

-18-

H. HIGH VOLTAGE CAPACITOR AND DIODE REMOVAL

Wire Leads

Turntable Motor

Figures 17

(1) Discharge the high voltage capacitor.
(2) Disconnect the wire lead from the high voltage capacitor.
(3) Remove the screw holding the high voltage capacitor

bracket.

J. REMOVING THE TURNTABLE MOTOR

(1) Remove the glass turntable & the rotating ring ASS’Y by

hand.

(2) Remove the turntable motor cover.

The turntable base cover is easily removed by pinching
the six parts with wire cutting pliers.

(3) Disconnect the wire lead from the turntable motor

terminals.

(4) Remove the screw securing the turntable motor to the

oven cavity assembly.

(5) After repairing the motor, rotate the removed turntable

motor cover.

(6) Fit the turntable motor cover's projecting part to the base

plate slit.

I. INTERLOCK SYSTEM

(1) INTERLOCK MECHANISM

The door lock mechanism is a device which has been
specially designed to eliminate completely microwave
activity when the door is opened during cooking and thus
to prevent the danger resulting from the microwave
leakage.

(2) MOUNTING OF THE PRIMARY/MONITOR/

SECONDARY SWITCHES TO THE LATCH BOARD

ADJUSTMENT
DIRECTION

SECONDARY
SWITCH

NOTE:

1. Remove the wire lead from the turntable motor VERY
CAREFULLY.

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

MONITOR
SWITCH

PRIMARY
SWITCH

Figures 18

(3) INSTALLATION AND ADJUSTMENT OF THE LATCH

BOARD TO THE OVEN ASSEMBLY

• Mount the latch board to the oven assembly.

• Adjust the latch board in the arrow direction so that oven

door will not have any play in it when the door is closed.

• Tighten the mounting screw.

• Check for play in the door by pushing the door

release button. Door movement should be less than

0.5 mm. (1/64 inch)

Don't push the door release button while making this
adjustment. Make sure that the latch moves smoothly after
adjustment is completed and that the screws are tight.
Make sure the primary, monitor, and secondary switches
operate properly by following the continuity test
procedure.

-19-

10. INTERLOCK CONTINUITY TEST

NO

COM

NC

COM

NO

COM

WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION

EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS.

TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR PRIMARY SWITCH
TYPE NO. SZM-V 16-FA-62 OR VP-532A-OF FOR MONITOR SWITCH
TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR SECONDARY SWITCH

A. PRIMARY INTERLOCK SWITCH TEST

When the door release button is depressed slowly with
the door closed, an audible click should be heard at
the same time or successively at intervals. When the
button is released slowly, the latches should activate
the switches with an audible click.
If the latches do not activate the switches when the
door is closed, the switches should be an adjusted in
accordance with the adjustment procedure. Disconnect
the wire lead from the primary switch. Connect the
ohmmeter leads to the common (COM) and normally
open (NO) terminal of the switch. The meter should
indicate an open circuit in the door open condition.
When the door is closed, the meter should indicate a
closed circuit.
When the primary switch operation is abnormal, make
the necessary adjustment or replace the switch only
with the same type of switch.

B. SECONDARY INTERLOCK SWITCH TEST

Disconnect the wire lead from the secondary switch.
Connect the ohmmeter leads to the common (COM)
and normally open (NO) terminals of the switch. The
meter should indicate a open circuit in the door open
condition. When the door is closed, meter should
indicate an closed circuit. When the secondary switch
operation is abnormal, make the necessary adjustment
or replace the switch only with the same type of switch.

C. MONITOR SWITCH TEST

Disconnect the wire lead from the monitor switch.
Connect the ohmmeter leads to the common (COM)
and normally closed (NC) terminals of the switch. The
meter should indicate closed circuit in the door open
condition. When the door is closed, meter should
indicate an open circuit. When the monitor switch
operation is abnormal, replace with the same type of
switch.
NOTE: After repairing the door or the interlock system,
it is necessary to do this continuity test before
operating the oven.

COMPONENTS TEST PROCEDURE RESULTS

SWITCHES Check for continuity of the Door Door
(Wire leads removed) switch with an Ohm-meter open closed

Primary
Switch

Monitor
Switch

Secondary
Switch

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

connected correctly.

-20-

O .L

O

O

O .L

OO .L

11. TEST AND CHECKOUT PROCEDURES, AND TROUBLESHOOTING

FILAMENT
WINDING

PRIMARY
TERMINAL

SECONDARY
WINDING

CAUTIONS

1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE OUTER CASE
FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH VOLTAGE CAPACITOR
AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE
TRANSFORMER.

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 TEST PROCEDURE RESULTS

HIGH VOLTAGE
TRANSFORMER
(Wire leads removed)

MAGNETRON
(Wire leads removed)

1. Measure the resistance.

2. Measure the resistance.

1. Measure the resistance.

2. Measure the resistance.

(Select the Ω scale on the meter)

• Primary winding

• Secondary winding

• Filament winding

(Select the Ω scale on the meter)

• Primary winding to ground

• Filament winding to ground

(Select the Ω scale on the meter)

• Filament terminal

(Select the Ω scale on the meter)

• Filament to chassis

Approx.: 0.2 ~ 0.4 ohm
Approx.: 50 ~ 90 ohm
Less than: 1 ohm

Normal: Infinite
Normal: Infinite

Normal: Less than 1 ohm

Normal: Infinite

-21-

COMPONENTS TEST PROCEDURE RESULTS

Antenna

Gasket

Chassis

Filament

Relay 2

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.

HIGH VOLTAGE
CAPACITOR

1. Check DC 9V battery before performing
tests.

2. Select the DCV scale on the meter.

3. Using the meter, battery, and jump wire,
connect the items as illustrated in figures.

󳥃

Terminal to terminal

󳥃

Terminal to case

Normal:
Approximately 9V

Normal:
Approximately 0V or
a value displayed in mV Will be seen.

RELAY 2

Check for continuity of relay 2 with an ohm­meter.
(Remove wire leads from relay 2 and
operate the unit.)

-22-

POWER

LEVEL

1
2
3
4
5
6
7
8
9

10

O O .L

4 sec
6 sec

8 sec
10 sec
12 sec
14 sec
16 sec
18 sec
20 sec
22 sec

18 sec
16 sec
14 sec
12 sec
10 sec

8 sec
6 sec
4 sec
2 sec
0 sec

COMPONENTS TEST PROCEDURE RESULTS

Figure 1 Figure 2 Figure 3

H.V.Diode (RECTIFIER)

STEP 1. Test the diode to see if it is
shorted.

Procedure:

1. Select the Ω scale on the meter.

2. Place the meter leads across the diode as
pictured in Figure 1. The reading should be
“40M Ω,” “OL,” or a reading of infinity.

3. Reverse the meter leads. The reading
should again indicate a reading of infinity. If
the diode shows “infinity” in BOTH
directions, it is NOT shorted.

4. If the diode is not shorted, proceed to step 2.

STEP 2. Test the diode for forward biasing.

Procedure:

1. Select the DCV scale on the meter.

2. Using the meter, battery and jumper wire,
connect the items as illustrated in Figure 2.
This has the positive side of the battery
connected to the cathode of the diode.

3. The diode should be forward biased
therefore a voltage reading of approximately

4.7 VDC to 6.4 VDC will be read depending
on meter, battery strength, etc. (Note: If the
meter leads were reversed, a negative
voltage of the same amount would be seen.)

Normal:
Approximately
4 .7-6.4V

STEP 3. Test the diode for reverse biasing.

Procedure:

1. Using the same scale on the meter, connect

the positive side of the battery to the anode
of the diode as illustrated in Figure 3.

2. The diode should be reverse biased
therefore a reading of 0 volt or a value
displayed in mV will be seen. (The display
will be erratic changing
values rapidly in the mV scale.)

Normal:
Approximately 0V

-23-

COMPONENTS TEST PROCEDURE RESULTS

FAN MOTOR
(Wire leads removed)

TURNTABLE
MOTOR
(Wire leads removed)

NOTE : • A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY

REASON.

• MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION.

•

WHEN REMOVING THE WIRE LEADS FROM THE PARTS, BE SURE TO GRASP THE CONNECTOR, NOT THE WIRES.

B. CHECKOUT PROCEDURES

(1) CHECKOUT PROCEDURES FOR FUSE BLOWING

CAUTION: REPLACE BLOWN FUSE WITH 20 AMPERE FUSE.

Measure the resistance.
(Select the Ω scale on the meter)

Measure the resistance.
(Select the Ω scale on the meter)

Normal: Approx. 65 ~ 80 ohm
Abnormal: Infinite or several

ohm.

Normal: Approx. 2 ~ 4K ohm
Abnormal: Infinite or several

ohm.

PROBLEMS CAUSES

Fuse blows immediately after
the door is closed.

Fuse blows immediately after
the door is opened.

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

NOTES:

- If the fuse is blown by an improper switch operation, replace the defective switches and the fuse at the same time. After
replacing the defective switches with new ones, make sure that they are correctly connected.

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

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

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

-24-

(2) CHECKOUT PROCEDURES FOR RELAY

-PROBLEM (A)­FAN motor and oven lamp turn on without touching
START key when the door is closed.

NO YES

GOOD

Remove the mate connector of I/O
CON from the circuit board. Does
the unit still operate?

NO

Replace the
circuit board

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

YES

GOOD

-PROBLEM (B)-

NO

Check the interlock switches

NO

YES

Replace the
micro switches.

-25-

Defective
RELAY or poor
connection of
relay

Replace
RELAY or correct
the connection.

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

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

SERVICED FOR ANY REASON.

(4) Some segments of one or more digits do not light up, or

they continue to light up, or segments light when they

should not.
(5) Wrong figures appear.
(6) The figures of all digits flicker.
(7) Some of the indicators do no light up.
(8) The clock does not keep time properly.

-26-

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 high voltage circuit.

3. Discharge the high voltage capacitor.

4. When checking the continuity of the switches or the high voltage transformer, disconnect one lead wire from these
parts and then check continuity with the AC plug removed. Otherwise it may result in a false reading or damage to
your meter.

5. Do not touch any part of the circuit on the PCB since static electric discharge may damage this control panel.
Always touch yourself to ground while working on this panel to discharge any static charge built up in your body.
(Micom model only)

CONDITION

Microwave oven

does not work.

Output power is too low. Low AC input voltage.

Sparks occur.

Inserting many plugs into one
outlet and using them at the
same time.
(blown fuse or breaker)

Microwave oven plug is not
inserted tightly.

Food temperature is too low.

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

CAUSE REMEDY

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

Insert microwave oven plug
securely.

Use the microwave oven at
adequate line voltage.

This may not be a defect.
It is possible that the food
should be cooked for a
longer time period.

Do not use metallic ware for
cooking except that noted in
the cooking guide.

Uneven cooking.

Ceramic ware trimmed in
gold or silver powder is used.

Inconsistent intensity of
microwave by their
characteristics.

-27-

Do not use any type of
cookware with metallic
trimming.

1. Use plastic wrap or lid.

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

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

1. Incomplete segments.

• Segment missing.

• Partial segment missing.

• Digit flickering (NOTE: Slight flickering is normal.)

2. Colon does not turn on or blink.

3. A distinct change in the brightness of one or more numbers in display.

4. One or more digits in the display are not lighting.

5. Display indicates a number different from one touched, for example, key in 5 and 3 appears in the display.

6. Specific numbers (for example 7 or 9) will not display when key pad is touched.

7. Display does not count down with time blinking or up with clock operation.

8. Display obviously jumps in time while counting down.

9. Display counts down too fast while cooking.

10. Each indicator light does not turn on after setting cooking cycle.

11. Display time of day does not reappear when cooking is finished.

CONDITION CHECK RESULT CAUSE REMEDY

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 the conn­ection between
membrane key
assembly and
PCB assembly.

Replace key
membrane
assembly and
check operation.

Continuity.

No continuity.

Everything works
as specified.

Still have trouble.

Defective PCB
assembly.

Loose
connection.

Defective key
membrane
assembly.

Defective PCB
assembly.

Replace PCB
assembly.

Connect them
tightly.

Replace key
membrane
assembly.

Replace PCB
assembly.

-28-

(TROUBLE 2)

CONDITION CHECK RESULT CAUSE REMEDY

Oven does not operate at all and Display window does not display any figures and no input is accepted.

1. Fuse blows. Continuity.

Check continuity
of monitor
switch (with
door closed).

Replace fuse

Check continuity
of primary
switch (with
door opened).

Disconnect one
side of the wire
lead connected
from transformer
to the high
voltage
capacitor and
operate the unit.

No continuity.

Continuity.

No continuity.

Normal.

Fuse blows again

Malfunction of the
monitor switch.

Shorted contact at
the primary switch.

Defective high
voltage capacitor.

Defective high volt­age transformer.

Replace fuse,
primary, monitor
switches, and
RELAY(RY2) of
P.C.B Assembly.

Replace fuse,
primary, monitor
switches, and
RELAY(RY2) of
P.C.B Assembly.

Replace high
voltage capacitor.

Replace high volt­age transformer.

2. Fuse does not
blow.

Check continuity
of thermostat.

Check continuity
of power supply
cord.

No continuity.

Continuity.

No continuity.

-29-

Defective
thermostat.

Defective power
supply cord.

Replace
thermostat.

Replace power
supply cord.

(TROUBLE 3) Display shows all figures set, but oven does not start cooking while desired

program times are set and START pad is touched.

CONDITION CHECK RESULT CAUSE REMEDY

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

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

Check continuity
of secondary
switch (with
door closed).

Check the con­nection between
CN1 connector
and PCB
assembly.

Check fan motor.

Check oven lamp.

No continuity.

Continuity.

Continuity.

No continuity.

Abnormal.

Abnormal.

Normal.

Defective
secondary switch.

Defective PCB
assembly.

Loose connection.

Defective fan motor.

Defective oven lamp.

Replace
secondary switch.

Replace PCB
assembly.

Connect them
tightly.

Replace fan motor.

Replace

oven lamp.

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

CONDITION CHECK RESULT CAUSE REMEDY

Output is low.

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.

Check the
power source
voltage.

Disconnect the
wire leads from
relay 2 and check
on and off time
with multitester.

Measure the
output power.

Lower than 90% of
rating voltage.

Normal.

Abnormal.

Normal.

Abnormal.

Decrease in power
source voltage
with load.

Defective PCB
assembly.

Defective
magnetron.

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

Replace PCB
assembly.

Replace
magnetron.

-30-

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

(Display operates properly)

CONDITION CHECK RESULT CAUSE REMEDY

No microwave
oscillation.

Disconnect the
wire leads from
relay 2 and
check continuity
of relay2.
(Operate the unit)

Check high vol­tage transformer

Check high vol­tage capacitor

Check high vol­tage diode

No continuity.

Continuity.

Abnormal

Normal

Abnormal

Normal

Abnormal

Defective PCB
assembly.

Defective high
voltage
transformer.

Defective high
voltage capacitor.

Defective high
voltage diode.

Replace PCB
assembly.

Replace high
voltage
transformer.

Replace high
voltage capacitor.

Replace high
voltage diode.

Normal

Check
magnetron.

NOTE : • Make sure the wire leads correct position.

• When Removing the wire leads from the parts, be sure to grasp the connector, not the wires.

• When removing the magnetron, be sure to install the magnetron gasket in the correct position

and in good condition.

Output is full power
when you set lower
power level.

Disconnect the
wire leads from
relay 2 and check
continuity relay 2.
(Operate the unit)

Abnormal

Abnormal.

-31-

Defective
magnetron.

Defective PCB
assembly.

Replace
magnetron.

Replace PCB
assembly.

DOOR PARTS

CONTROL PANEL PARTS

BASE PLATE PARTS

OVEN CAVITY PARTS

LATCH BOARD PARTS

INTERIOR PARTS

#EV#

EXPLODED VIEW

INTRODUCTION

Model: 721.62222300 / 721.62222301

721.62229300 / 721.62229301

-32-

1003

1001

1000

1006

1007

1004

1005

1013

1002

#EV#

DOOR PARTS

-33-

2000

2002

2001

2381

2006

W106

2003

2005

2007

2004

2010

#EV#

CONTROL PANEL PARTS

-34-

W103

3001

3003

W107

3002

3009

W105

3034

3008

For Model 721.62229

For Model 721.62222

W118

#EV#

OVEN CAVITY PARTS

-35-

4003

4000

4002

4002

W102

#EV#

LATCH BOARD PARTS

-36-

W101

W101

5040

5015

5006

5000

W109

W101

5002

5018

W101

W110

5003

5012

W109

W101

5007

5001

5016

5014 5005

W101

5010

5009

3006

* Check the
Model No.

* Check the
Model No.

* Check the
Model No.

* Check the
Model No.

9000

#EV#

INTERIOR PARTS (I)

Model: 721.62222300

721.62229300

Check the rating label of Model and order
SVC parts according to the Model No.

-37-

W101

W101

5040

5015

5006

5000

W109

W101

5002

5018

W101

W110

5003

5041

5012

W109

W208

5007

5001

5016

5014

W101

5010

5009

3006

* Check the
Model No.

* Check the
Model No.

* Check the
Model No.

* Check the
Model No.

9000

#EV#

INTERIOR PARTS (II)

Model: 721.62222301

721.62229301

Check the rating label of Model and order
SVC parts according to the Model No.

-38-

W101

6002

W109

W108

5008

6000

6001

9001

#EV#

BASE PLATE PARTS

-39-

P/NO : 3828W5S5230 Printed in Korea