Kenmore 721.66993 Service Manual
삼 흥
정 판
MODEL 721.66993
DIVISION 20
BASIC FIELD MANUAL
FOR
PIZZA OVEN AND MICROWAVE OVEN
MODEL 721.66993800
December, 2007
CAUTION
WARNING TO SERVICE TECHNICIANS
PRECAUTIONS TO BE OBSERVED BEFORE
AND DURING SERVICING TO AVOID
POSSIBLE EXPOSURE TO EXCESSIVE
MICROWAVE ENERGY
a. Do not operate or allow the oven to be operated with the door open.
b. Make the following safety checks on all ovens to be serviced before activating the magnetron or other
microwave source, and make repairs as necessary; (1) Interlock operation, (2) proper door closing, (3)
seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or loosening of hinges and
latches, (5) evidence of dropping or abuse.
c. Before turning on microwave for any service test or inspection within the microwave generating
compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment,
integrity, and connections.
d. Any defective or misadjusted components in the interlock, monitor, door seal, and microwave
generation and transmission systems shall be repaired adjusted by procedures described in this
manual before the oven is released to the owner.
e. A Microwave leakage check to verify compliance with the Federal performance standard should be
performed on each oven prior to release to the owner.
• Proper operation of the microwave ovens requires that the magnetron be assembled to the wave guide and
cavity. Never operate the magnetron unless it is properly installed.
• Be sure that the magnetron gasket is properly installed around the dome of the tube whenever installing the
magnetron.
• Routine service safety procedures should be exercised at all times.
• Untrained personnel should not attempt service without a thorough review of the test procedures and safety
information contained in this manual.
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FOREWORD
Read this Manual carefully. Failure to adhere to or observe the information in this Manual may result in exposing yourself to
the Microwave Energy normally contained within the oven cavity.
MODEL 721.66993
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 ....................................................................................................................................................6-7
6. Overall Circuit Diagram .....................................................................................................................................8-9
7. Operating Procedures .......................................................................................................................................10-12
8. Procedure for Measuring Microwave Energy Leakage .....................................................................................13-14
9. Disassembly Instructions ..................................................................................................................................15-22
10. Interlock Continuity Test .................................................................................................................................23
11. Test and Checkout Procedures, and Troubleshooting
A. Test Procedures .........................................................................................................................................23-27
B. Checkout Procedures .................................................................................................................................28-30
C. Troubleshooting ..........................................................................................................................................31-36
12. Exploded View ................................................................................................................................................37-44
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1. ADJUSTMENT PROCEDURES
To avoid possible exposure to microwave energy
leakage, adjust the door latches and interlock switches,
using the following procedure.
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 acts
as the final safety switch protecting the user from
microwave energy. The terminals between “COM” and
“NC” of the Interlock Monitor must close when the door
is opened. After adjusting the Interlock Monitor Switch,
make sure that it is correctly connected. See Figures 1-a
and 1-b throughout this procedure.
CHECK THE DOOR LATCH AND SWITCH
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 is very important.
If any gap is larger than 1/64” (0.5 mm), you will need to
adjust the latch board-U, L. Go to step 3 and follow all
steps in order.
(4) With the oven door closed tightly, move the latch board
upward toward the top of the oven and/or away from the
door latch until the gaps are less than 1/64” (0.5 mm).
Hold the latch board tightly in this position until you
check the sequence of the switches in steps 5 and 6.
TEST THE LATCH AND SWITCH SEQUENCE
(5) Open the oven door slowly. Watch the door latch, the
Primary Switch. Release Rod and Lever on the switches
to make sure they are zero to the body of the switches
in the following sequence:
- Primary Interlock Switch
- Secondary Interlock Switch
- Interlock Monitor Switch
Adjust the latch board until the switches operate in this
sequence. See Steps 3 and 4.
(6) Close the oven door slowly and be sure it is tightly
closed. Watch the three switches to make sure they are
zero to the body of the switches in the following
sequence:
- Interlock Monitor Switch
- Primary Interlock Switch
- Secondary Interlock Switch
NOTE: The Interlock Monitor Switch is an added safety
check on the Primary and Secondary Interlock
Switches. If the Primary and Secondary Interlock
Switches allow the oven to operate with the door
open, the Monitor Switch will blow the fuse.
(7) When you achieve the proper sequence of switches in
Steps 5 and 6, tighten the latch board screws at that
point.
TEST THE MICROWAVE ENERGY LEAKAGE
(8) Using a survey meter, make sure the microwave energy
is below 5 mW/cm.sq.
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Latch Board
A
Interlock
Monitor Switch
Secondary
Interlock Switch
0-1/64"
LATCH BOARD
Primary
Interlock Switch
LATCH
0-1/64"
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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 34 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. And do not place on or near
a hot gas or electric burner or in a heated oven.
CAUTION
This unit is equipped with a 3-prong plug for your safety.
If the wall outlet is a grounded 3-hole type, the unit will
be grounded automatically.
Properly Polarized and
Grounded
Outlet
Three-Pronged(Grounding)
Plug
Figure 2
3. GENERAL PRECAUTIONS IN USE
Microwave Oven
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.
Pizza Oven
A. Never operate the oven when it is empty. Operating the
oven with no load may overheat this appliance.
B. Oversized food, metal foil packages or utensils must not
be inserted in this oven, as they may create a fire or
electrical hazards.
4. TRIAL OPERATION
After installation, the following sequences and results
should be checked carefully.
Microwave Oven
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. “10:00” appears in the
display window.
D. Touch the START key.
Make sure the cavity light comes on. The unit will begin
cooking and the display window will show the time
counting down by seconds.
E. After about 5 minutes, make sure the primary interlock
switch, the secondary interlock switch and the interlock
monitor and oven lamp switch operate properly by
opening and closing the door several times. Touch the
START key each time the door is closed.
F. Continue operating the unit. 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 14.
Pizza Oven
A. Remove all protective wrappings from food before
placing into metal tray. Metal tray with pizza place on
the shelf and close the door.
B. Select one mode(Auto Pizza/Bake).
Touch this pad to select programing food items.
a) In case of auto pizza touch this pad to select
programing food items.
b) In case fo bake touch this pad to select sat a tem
perature and cooking times.
C. The cooling fan turns on during the cooking.
Beep sound signal is heard when the time is up.
The unit will shut off automatically and fan will blow.
If oven temperature is above 325˚F
NOTE : If you operate this pizza for the first time, you will
notice an odor, that is a characteristic of burning off
residues on the new heating elements. This is
normal.
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5. FEATURES AND SPECIFICATIONS
Microwave Oven
A. The safety systems incorporated in this oven 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
900W can be selected by the touch control and
electronic computer system.
C. Cooking time can be displayed on the digital readout.
And MWO mode and Pizza oven mode can be displayed
to avoid confusion.
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.
Pizza Oven
A. The safety systems incorporated in this pizza oven are:
(1) Door switch
(2) Thermostat
(Note : This thermostat located on the oven side will
open and stop the unit from operation only if a
high temperature is reached, such as, a fire
created by overcooking food.)
B. Cooking mode auto pizza and bake and browning level
can be displayed on the digital readout.
C. Thermister controls the cooking time by detecting the
internal temperature. This makes it possible to cook
pizza evenly.
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SPECIFICATIONS
Rated Power Consumption ................................... 1450W
Output
Microwave oven ................................................. 1000W (*IEC60705 Rating standard)
Adjustable 100W through 1200W,10 steps
Pizza oven ......................................................... 1400W
Frequency ............................................................. 2450 MHz ± 50 MHz
Power Supply......................................................... 120V ±12V AC, 60Hz
Rated Current ....................................................... 12.5 Amp.
Magnetron & Heater Cooling ................................ Forced Air Cooling
Microwave Stirring ................................................ Turntable
Rectification ........................................................... Rectification Voltage Doubler Half-Wave
Door Sealing ......................................................... Choke System
Safety Devices
Microwave oven ................................................. Thermostat: Open at 90°C ± 5°C, Close at 75°C ± 5°C
Fuse(20A)
Primary Interlock Switch
Secondary Interlock Switch
Interlock Monitor
Pizza oven ......................................................... Pizza Oven Door Switch
Thermostat: Open at 145°C ± 5°C, Close at 0°C ± 5°C
Magnetron ............................................................. 2M246
High Voltage Capacitor ......................................... Capacitor: 0.91µF, 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
Thermistor, NTC ................................................... 150°C ± 3%
Overall Dimensions ............................................... 233/4”(W) x 177/16”(H) x 191/4”(D)
Oven Cavity Size .................................................. 1915/
16”(W) x 15
1
/
2”(H) x 17
Effective Capacity of Oven Cavity ......................... 1.1 Cu.ft.
Accessories .......................................................... Use and Care Manual ,Glass Turntable,
Turntable Rotating Ring, Shelf, Metal Tray
1
/
4”(D)
SWITCH CHART
SECONDARY
INTERLOCK
SWITCH
COM
SWITCH MODE
CONDITIONS
DOOR OPEN
DOOR CLOSED
PRIMARY
INTERLOCK
SWITCH
COM
NO
∞∞0
00∞
NOTE: Use the above switch table with circuit diagram on page 8.
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NO
INTERLOCK
MONITOR
SWITCH
COM
NC
PIZZA OVEN
DOOR
SWITCH
COM
NO
∞
0
6. OVERALL CIRCUIT DIAGRAM
A. SCHEMATIC DIAGRAM
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B. MATRIX CIRCUIT FOR TOUCH KEY BOARD
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7. OPERATING PROCEDURES
A. OVEN CONTROL PANEL
1
2
3
4
6
7
10
11
5
8
9
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 COOKING. These pads allow you to
cook most of your favorite foods without having to
select cooking times and power levels.
3. NUMBER PADS. Touch Number Pads to enter cooking
time, power level, quantities, or weights.
4. COOK TIME. Touch this pad to set a cooking time.
5. POWER. Touch this pad to set a cooking power.
6. STOP. Touch this pad to stop the oven or clear entries.
7. START. Touch this pad to start all entries (except the
Quick Touch Sensor, Express Defrost, Auto Cook and
Add Minute function which start automatically).
8. MORE. Touch this pad to add 10 seconds of cook time
each time you press it.
9. LESS. Touch this pad to subtract 10 seconds of cook
time each time you press it.
10. AUTO PIZZA. Touch This Pad to select Programming
Food Items.
11. BAKE. Touch This Pad to select sat a Temperature
and cooking times.
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C. EASY USE TABLE
MICROWAVE OVEN
(1) KITCHEN TIMER
1. Touch STOP.
2. Touch KITCHEN TIMER.
3. Touch correct number for time.
4. Touch START.
(2) CHILD LOCK
To set:
1. Touch STOP.
2. Touch “START” more than 4 seconds.
To cancel:
1. Touch STOP.
2. Touch “START” more than 4 seconds.
(3) AUTO COOK
1. Touch STOP.
2. Touch AUTO COOK Category.
3. Touch START.
(Although you don’t touch start, it will start after
4 seconds automatically)
(4) QUICK TOUCH PLUS
1. Touch STOP.
2. Touch QUICK TOUCH PLUS.
PIZZA OVEN
(1) AUTO PIZZA
1. Touch STOP.
2. Touch AUTO PIZZA.
Four different defrosting levels are provied
(Touch 1 : Frozen Rising Crust
Touch 1 : Frozen Regular Crust
Touch 1 : Fresh Regular Crust
Touch 1 : Fresh par-baked Crust )
3. Touch START.
(2) BAKE
1. Touch STOP.
2. Touch BAKE.
Four different defrosting levels are provied
(Touch 1 : 425 F
Touch 1 : 400 F
Touch 1 : 375 F
Touch 1 : 350 F ).
3. Touch number for cooking time.
4. Touch START.
(5) AUTO DEFROST
1. Touch STOP.
2. Touch AUTO DEFROST.
Three different defrosting levels are provided.
(Touch 1 : Meat
Touch 2 : Poultry
Touch 3 : 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.
6. After turning food over, touch START to resume
defrosting.
(6) TIMED COOKING
1. Touch STOP.
2. Touch COOK TIME.
3. Touch number for cooking time.
4. Touch POWER.
5. Touch number for cooking power level.
6. Touch START.
(7) MULTI-STAGE COOKING
1. Touch STOP.
2. Touch COOK TIME.
3. Touch number 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.
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8. PROCEDURE FOR MEASURING MICROWAVE
ENERGY LEAKAGE
A. CAUTIONS
(1) Be sure to check a microwave emission prior to servicing
the oven if the oven is operative prior to servicing.
(2) The service personnel should inform the manufacturer,
importer, or assembler of any certified oven unit found to
have a microwave emission level in excess of
5mW/cm.sq. and should repair any unit found to have
excessive emission levels at no cost to the owner and
should ascertain the cause of the excessive leakage.
The service personnel should instruct the owner not to
use the unit until the oven has been brought into
compliance.
(3) If the oven operates with the door open, the service
personnel should;
- Tell the user not to operate the oven
- Contact the manufacturer and CDRH (Center for
Devices and Radiological Health) immediately.
NOTE: Address on CDRH
Office of Compliance (HFZ-312)
Center for Devices and Radiological Health
1390 Piccard Drive
Rockville, Maryland 20850
(4) The service personnel should check all surface and vent
openings for microwave emission testing.
(5) Check for microwave energy leakage after every
servicing. The power density of the microwave radiation
leakage emitted by the microwave oven should not
exceed 1mW/cm.sq. And always start measuring of an
unknown field to assure safety for operating personnel
from radiation leakage.
NOTE: The standard is 5mW/cm.sq. while in the
customer’s home. 1mW/cm.sq. stated here is
manufacturer’s own voluntary standard for units in
customer’s home.
EQUIPMENT
• Electromagnetic energy leakage monitor (NARDA 8100B,
HOLADAY HI 1501)
• 600cc glass beaker
• Glass thermometer 100°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 2450 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 6)
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.
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