Sears 721.80802, 721.80809, 721.80804, 721.80803 Basic Field Manual
DIVISION 22
BASIC FIELD MANUAL
FOR
MICROWAVE OVEN
MODEL 721.80802400 / 721.80802401
721.80809400 / 721.80809401
721.80804400 / 721.80804401
721.80803400 / 721.80803401
June, 2005
MODEL 721. 80802
721. 80809
721. 80804
721. 80803
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.
TABLE OF CONTENTS
(Page)
SAFETY PRECAUTIONS .............................................................................................................. Inside front page
SPECIFICATIONS ............................................................................................................................................... 1-1
CAUTIONS .......................................................................................................................................................... 2-1
INSTALLATIONS ................................................................................................................................................. 3-1
OPERATING INS ................................................................................................................................................. 4-1
CONTROL PANEL ....................................................................................................................................... 4-1
CONTROL PANEL INSTRUCTIONS ........................................................................................................... 4-2
OVERALL CIRCUIT DIAGRAM ........................................................................................................................... 5-1
SCHEMATIC DIAGRAM (I) .......................................................................................................................... 5-1
SCHEMATIC DIAGRAM (II) ......................................................................................................................... 5-2
MATRIX CIRCUIT FOR TOUCH KEY BOARD ............................................................................................ 5-3
GENERAL INFORMATION FOR SERVICE ........................................................................................................ 6-1
GENERAL PRECAUTIONS IN USE ............................................................................................................ 6-1
TRIAL OPERATION ..................................................................................................................................... 6-1
FEATURES AND SPECIFICATIONS FEATURES ...................................................................................... 6-1
SERVICE INFORMATION ................................................................................................................................... 7-1
PRECAUTIONS AND REPAIR SERVICE TIPS ........................................................................................... 7-1
MICROWAVE LEAKAGE TEST ................................................................................................................... 7-2
POWER OUTPUT MEASUREMENT ........................................................................................................... 7-3
DISASSEMBLY INSTRUCTIONS ................................................................................................................ 7-4
INTERLOCK SYSTEM ............................................................................................................................... 7-12
INTERLOCK CONTINUITY TEST .............................................................................................................. 7-14
TEST AND CHECKOUT PROCEDURES AND TROUBLE SHOOTING ................................................... 7-15
A. TEST PROCEDURES .................................................................................................................... 7-15
B. CHECKOUT PROCEDURES ......................................................................................................... 7-19
C. TROUBLE SHOOTING .................................................................................................................. 7-22
EXPLODED VIEW ............................................................................................................................................... 8-1
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. 80802
721. 80809
721. 80804
721. 80803
1-1
Rated Power Consumption
1700W maximum (Microwave oven+Cook top lamps+Ventilation fan)
Microwave Output 1150W (IEC 60705)
Frequency 2,450 MHz ± 50 MHz
Power Supply 120 VAC, 60 Hz
Rated Current 15.5 Amp. (Microwave oven+Cook top lamps+Ventilation fan)
Magnetron Cooling Forced Air Cooling
Rectification Rectification Voltage Double Half-Wave
Door Sealing Choke System
Safety Devices Magnetron Thermostat: Open at 145 °C ±5 °C
Close at 60 °C ±5 °C
Oven Thermostat: Open at 110 °C ±5 °C
Close at 0 °C ±5 °C
Fuse(20A)
Primary Interlock Switch
Secondary Interlock Switch
Interlock Monitor Switch
Magnetron 2M282J (Toshiba)
Cook top Lamp 120 V, 20 W (Halogen)
Cavity Lamp 120 V, 20 W (Halogen)
Timer Digital, up to 99 min. (in each cooking stage)
Tray Tempered Safety Glass
Overall Dimensions 29
15
/16”(W)x167/16”(H)x153/8”(D)
Oven Cavity Size 23
1
/2”(W)x10”(H)x141/2”(D)
Effective Capacity of Oven Cavity 2.0 Cu.ft.
Accessories Owner ’s Manual & Cooking Guide, Installation Manual,
Exhaust Adapter, Exhaust Damper, Mounting Kit and Filter,
Rotating Ring Assembly, Glass Tray, Metal Rack, Guide Tray.
SWITCH CHART
SPECIFICATIONS
NOTE: Use the above switch chart with circuit diagram on page 5-1.
PRIMARY SECONDARY INTERLOCK
INTERLOCK INTERLOCK MONITOR
SWITCH SWITCH SWITCH
COM COM COM
NO NO NC
OPEN OPEN CLOSE
CLOSE CLOSE OPEN
SWITCH MODE
CONDITIONS
DOOR OPEN
DOOR CLOSED
2-1
CAUTIONS
• 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.
• 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.
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.
THE OVEN IS TO BE SERVICED ONLY
BY PROPERLY QUALIFIED SERVICE
PERSONNEL.
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.
Gasket
ANTENNA
COOLING FIN
MAGNETRON
CHASSIS GROUND
FILAMENT
TERMINALS
MAGNETRON
3-1
INSTALLATIONS
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.
BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY.
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.
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
CONTROL PANEL
4-1
OPERATING INSTRUCTIONS
MAIN MENU
Cook
Reheat
Defrost
Soften & Melt
Favorites
Options
1
2
3
5
6
8
10
4
7
9
11
CONTROL PANEL INSTRUCTIONS
4-2
1. Display Screen shows the time of day and Cook Mode
when the microwave oven is not in use. During
programming, it displays function menus for you to
choose from, servings and weights for you to enter,
preparation instructions, and cooking time/power
settings for you to select. During a cooking cycle, it
counts down the remaining time and prompts you to stir,
turn food, etc., as necessary.
2. Touch DIAL Control. Use this dial to select oven
functions, such as quantities of food and cooking
times/powers.
3. START. Touch this pad to start a function. If you open
the door after the oven beings to cook, retouch start.
4. STOP/CLEAR. Touch this pad to stop and cancel any
oven function.
5. MANUAL COOK. Touch this pad for manual control of
cook time and power level. The Stop/Clear pad can also
be used to cancel.
6. POPCORN. Touch this pad 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.
7. ADD 30 SECOND. Touch this pad to cook for 30
seconds at 100% cook power, or to add extra seconds
at the set cook power to your cooking cycle.
8. CLOCK. Touch this pad to enter the time of day.
9. KITCHEN TIMER. Touch this pad to set the Kitchen
Timer.
10. VENT. Touch this pad to display the hood vent fan
speed settings. Turn dial to set the fan speed and
Press.
11. LIGHT.Touch this pad to display the dark and bright
settings.
OVERALL CIRCUIT DIAGRAM
SCHEMATIC DIAGRAM (I) *Check the Model No.
5-1
SCHEMATIC DIAGRAM (II) *Check the Model No. (ADD Noise filter)
BN
H.V.DIODE
THERMOSTAT
M.G.T
THERMOSTAT
OVEN
SECONDARY
SWITCH
H.V.
BK
O.L
PRIMARY
SWITCH
RD
RD
RS.
RC.
F.M
T.T.M
BN
MONITOR
SWITCH
RD
TRANSFORMER
H.V.
WH
V.M
CAPACITOR
C.L
S.M
HIGH
C
CONDENSER
BL
THERMISTOR
ABSOLUTE
HUMIDITY
SENSOR
YL
BK
RD
RD
RD
BK
RD
RD
BK
BL
BL
BK
BK
BK
BN
RD
BL
WH
WH
WH
WH
WH
YL
YL
YL
PK
BL
1
2
3
1
2
3
5
CN1
CN4
RY2
POWER
RELAY
123456
123456
12
12
6
7
TAP
3
TAP
2
1
TAP
4
YL RD BK BNBL WH BKRDWH
7 PIN CONNECTOR(CN1) 3 PIN CONNECTOR(CN4)
CONTROL MODULE
WIRE COLORS
3 PIN(CN7)
CONNECTOR
(FOR SENSOR)
PK BL
CN7
321
RY15
3 TAP
POWER
RELAY
SCR1
VENT
FAN
5 LVL
RY11
FAN
MOTOR
RELAY
RY6
VENT
FAN
ON/OFF
RELAY
SCR2
C/TOP
LAMP
5 LVL
RY14
C/TOP
LAMP
ON/OFF
RELAY
RY1
MAIN
RELAY
L.V.
TRANSFORMER
F
FA
MAGNETRON
5-2
5-3
MATRIX CIRCUIT FOR TOUCH KEY BOARD
Start
Enter Popcorn Clock Light
Add 30
Stop/
Clear
Manual
Cook
Vent
N.C
N.C
Kitchen
Timer
6
7
5
1
2
3
4
6-1
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.
C. Press DIAL to start.
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. Press
the DIAL key each time the door is closed.
E. Continue operating the unit. For 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
1150W can be selected by the touch control and
electronic computer system.
GENERAL INFORMATION FOR SERVICE
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
PRECAUTIONS AND REPAIR SERVICE TIPS
SERVICE INFORMATION
7-2
CAUTIONS
• Be sure to check microwave leakage prior to
servicing the oven if the oven is operative prior to
servicing.
• The service personnel should inform the
manufacture importer, or assembler of any certified
oven unit found to have a microwave emission level
in excess of 5 mW/cm2and should repair any unit
found to have excessive emission levels at no cost to
the owner and should ascertain the cause of the
excessive leakage. The service personnel should
instruct the owner not to use the unit until the oven has
been brought into compliance.
•
If the oven operates with the door open, the service
personnel should;
- Tell the user not to operate the oven
- Contact the manufacturer 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)
MICROWAVE LEAKAGE TEST
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