Kenmore 767.8541901, 767.85419, 767.8541301, 767.85413, 767.8541001 Service Manual
...
TECHNICAL FLASH
Department 731A Toronto
BASIC SERVICE MANUAL
T.F. 22-480
FOR
MICROWAVE OVEN
MODEL 767.8541000 / 767.8541001
767.8541300 / 767.8541301
767.8541900 / 767.8541901
MARCH, 2005
CAUTION
SAFETY PRECAUTIONS
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 CSA Standard should be
performed on each oven prior to release to the owner.
• Proper operation of the microwave ovens requires that the magnetron be assembled to the
wave guide and cavity. Never operate the magnetron unless it is properly installed.
• Be sure that the magnetron gasket is properly installed around the dome of the tube whenever
installing the magnetron.
• Routine service safety procedures should be exercised at all times.
• Untrained personnel should not attempt service without a thorough review of the test
procedures and safety information contained in this manual.
FOREWORD
Read this Manual carefully. Failure to adhere to or observe the information in this Manual may result in exposing
yourself to the Microwave Energy normally contained within the oven cavity.
TABLE OF CONTENTS
(Page)
SAFETY PRECAUTIONS ................................................................................................................... Inside front page
SPECIFICATIONS..................................................................................................................................................... 1-1
CAUTIONS ............................................................................................................................................................... 2-1
INSTALLATION ....................................................................................................................................................... 3-1
OPERATING INS ..................................................................................................................................................... 4-1
CONTROL PANEL............................................................................................................................................. 4-1
CONTROL PANEL INSTRUCTIONS................................................................................................................. 4-2
OVERALL CIRCUIT DIAGRAM................................................................................................................................. 5-1
SCHEMATIC...................................................................................................................................................... 5-1
MATRIX CIRCUIT FOR TOUCH KEY BOARD ................................................................................................. 5-2
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 ............................................................................................................... 7-18
C. TROUBLE SHOOTING ........................................................................................................................ 7-21
EXPLODED VIEW..................................................................................................................................................... 8-1
REPLACEMENT PARTS LIST........................................................................................................................... 8-8
SPECIFICATIONS
Rated Power Consumption
Microwave Output
Frequency
Power Supply
Rated Current
Magnetron Cooling
Rectification
Door Sealing
Safety Devices
Magnetron
High Voltage Capacitor
High Voltage Diode
Cook top Lamp
Cavity Lamp
Timer
Tray
Overall Dimensions
Oven Cavity Size
Effective Capacity of Oven Cavity
Accessories
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1500W maximum (Microwave oven+Cook top lamps+Ventilation fan)
1000W (IEC60705)
Adjustable 100W through 1000W, 10 steps
2450 MHz ± 50 MHz
120 VAC, 60 Hz
13 Amp. (Microwave oven+Cook top lamp+Ventilation fan)
Forced Air Cooling
Rectification Voltage Double Half-Wave
Choke System
Oven Cavity Thermostat:
Open at 90°C ± 5°C
Fuse(20A)
Primary Interlock Switch
Secondary Interlock Switch
Interlock Monitor
2M214-161GP
Capacitor: 1.0µF, 2.1 KV AC
Diode; 350mA, 9.0 KV
125 V, 30 W
125 V, 30 W
Digital, up to 99 mim. 99 sec. (in each cooking stage)
Tempered Safety Glass
15
/16"(W)x167/16"(D)x153/8"(H)
29
197/8"(W)x143/16"(D)x815/16"(H)
1.6 Cu.ft.
Owner’s Manual & Cooking Guide, Installation Manual,
Exhaust Adapter, Exhaust Damper, Mounting Kit and Two Filters,
Rotating Ring Assembly.
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.
• For about 30 seconds after the oven stops, an electric
charge remains in the high voltage capacitor. When
replacing or checking, you must discharge the high
voltage capacitor by shorting across the two terminals
with an insulated screwdriver.
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.
• 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.
ANTENNA
Gasket
COOLING FIN
FILAMENT
TERMINALS
MAGNETRON
CHASSIS GROUND
MAGNETRON
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 15A
or 20A.
B. Avoid placing the unit in a location where there is
direct heat or splashing water.
C. Install the unit on the mounting plate firmly.
D. Place the unit as far away as possible from TV,
radio, etc. to prevent interference.
GROUNDING INSTRUCTIONS
For personal safety, this appliance must be fully
grounded at all times.
In the event of an electrical short circuit, grounding
reduces the risk of electrical shock.
The plug must be plugged into an outlet that is
properly installed and grounded.
CAUTION
This unit is equipped with a 3-prong plug for your
safety. If the wall outlet is a grounded 3-hole type,
the unit will be grounded automatically.
Plug with Ground
Prong
Properly Polarized
and Grounded
Outlet
WARNING
Improper use of the grounding plug can result in a
risk of electric shock.
Do not, under any circumstances, cut or remove the
third ground prong from the power cord plug.
3-1
CONTROL PANEL
OPERATING INSTRUCTIONS
For Model 85410
4-1
CONTROL PANEL INSTRUCTIONS
1. DISPLAY: The Display includes a clock and indicators to
tell you time of day, cooking time settings and cooking
functions selected.
2. POPCORN: Touch this pad when popping popcorn in
your microwave oven.
3. PIZZA: Touch this pad to reheat 1 to 3 slices.
4. COOK: Touch this pad to cook vegetables, rice, or
casseroles.
5. POTATO: Touch this pad to cook potatoes from 1 to 4.
6. BEVERAGE: Touch this pad to reheat one cup or two
cups a beverage.
7. REHEAT: Touch this pad to reheat dinner plate,
soup/sauce, casserole, roll/muffin.
8. MORE: Touch this pad to add ten seconds of cooking
time each time you press it.
9. CUSTOM COOK: Touch this pad to recall one cooking
instruction previously programmed into memory.
10. LESS: Touch this pad to subtract ten seconds of cooking
time each time you press.
14. TIME: Touch this pad to set a cooking time.
15. POWER: Touch this pad to select a cooking power level.
16. CUSTOM SET: Touch this pad to change the oven’s
default settings for sound, clock, display speed and
defrost weight.
17. TIME OF DAY: Touch this pad to enter the time of day.
18. HOLD WARM: Touch this pad to keep hot, cooked foods
safety warm in your microwave oven for up to 99 minutes
99 seconds.
19. HELP: Touch this pad to learn how to use each oven
function.
20. STOP/CLEAR: Touch this pad to stop the oven or clear
all entries.
21. START: Touch this pad to start a function. If you open
the door after oven begins to cook, retouch START.
22. KITCHEN TIMER: Touch this pad to set the kitchen
timer.
23. ON/OFF: Touch this pad to turn off the turntable.
“OFF” will appear in the display.
11. EXPRESS DEFROST: Meat, poultry, fish. Touch on pad
to select food type and defrost food by weight.
12. QUICK TOUCH PLUS: Touch this pad to set and start
quickly at 100% power level.
13 NUMBER: Touch number pads to enter cooking time,
power level, quantities or weights.
24. LIGHT TIMER: Touch this pad to set the light timer.
25. HI/LOW/OFF: Touch this pad to turn the fan on or
off.
26. HI/LOW/OFF: Touch this pad to turn on the
cooktop/countertop light.
4-2
OVERALL CIRCUIT DIAGRAM
SCHEMATIC DIAGRAM
5-1
MATRIX CIRCUIT FOR TOUCH KEY BOARD
5-2
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. Four 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) Magnetron thermal fuse
(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.
6-1
SERVICE INFORMATION
PRECAUTIONS AND REPAIR SERVICE TIPS
PRELIMINARY
A. SINCE NEARLY 2,100 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 bebelow
the limit of 5 mW/cm2.
(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/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.
• The service personnel should check all surface and
vent openings for microwave leakage.
• Check for microwave leakage after every servicing. The
power density of the microwave radiation leakage
emitted by the microwave oven should not exceed
4 mW/cm2. Always start measuring of an unknown field
to assure safety for operating personnel from radiation
leakage.
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 center of the turntable.
• 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 an
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)
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 (31/2in.)
• Glass thermometer: 100°C or 212°F (1 deg scale)
7-2
MEASUREMENT WITH THE OUTER CASE
WATER LOAD
TURNTABLE
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/cm2. Leakage for a fully assembled oven
(“Before the latch switch (primary) is interrupted”)
with the door in a slightly opened position - less
than 2 mW/cm2.
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 being
tested. (Hold vertically when testing the top and
bottom, and horizontally along the side.)
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 2 mW/cm2after 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 prior to the start of the test.
(4) The initial temperature (T1) of the water is (10±2)°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±2)°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 =
is measured while the microwave generator is
operating at full power. Magnetron filament heat-up
time is not included. (about 3 sec)
(7) The water is stirred to equalize temperature
throughout the vessel, prior to measuring the final
water temperature.
(8) Stirring devices and measuring instruments are
selected in order to minimize addition or removal of
heat.
4.187Mw(T2 – T1)+0.55Mc(T2 – T0)
t
7-3
DISASSEMBLY INSTRUCTIONS
Figure 1
Screw
Control Panel
(Relay 7)
Relay 7
Power Transformer
(CN1)
Circuit Board
Figure 2
Figure 3
Control Bracket
FPC Connector(S1)
Circuit Board
IMPORTANT NOTES:
UNIT MUST BE DISCONNECTED FROM ELECTRICAL OUTLET WHEN MAKING REPAIRS, REPLACEMENTS, 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 10K-OHM 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 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 connector (CN1) and wire leads
(Relay6) from the circuit board.
(4) Remove 3 screws securing the circuit board.
(5) Remove the FPC connector from the terminal
socket following “HOW TO REMOVE THE FPC
CONNECTOR” on the next page.
(6) Remove the circuit board from the control bracket
carefully.
7-4
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