SHARP R930AKAW Service Manual
R-930AK
R-930AW
SER VICE MANU AL
S6710R930APW/
CONVECTION
MICROWAVE OVEN
MIX CONV
DEFROST
SENSOR
COOKLBS OZ KG HELP
CUSTOM
Interactive
HELP
SENSOR
MINUTE
REHEAT
PLUS
POPCORN
COMPU
ELEVATE PKG
DEFROST
1 Baked potatoes
2 Frozen vegetables
3 Fresh veg-soft
4 Fresh veg-hard
5 Frozen entrees
6 Hot dogs
SENSOR
7 Bacon
COOKT
8 Fish, seafood
Convection
1 Hamburgers
2 Chicken pieces
COMPU
3 Steaks
BROIL
4 Fish steaks
1 Chicken
2 Turkey
COMPU
3 Turkey breast
ROAST
4 Pork
1 Bundt cake
2 Cookies
COMPU
3 Muffins
BAKE
4 French fries
PREHEAT CONVEC BROIL
SLOW
LOW MIX
HIGH MIX
COOK
BAKE
ROAST
12345
100˚F 150˚F 275˚F 300˚F 325˚F
67890
350˚F 375˚F 400˚F 425˚F 150˚F
KITCHEN
ST OP
CLOCK
TIMER
TCLEAR
POWER
START
LEVEL
SMART & EASY
CONVECTION
TOUCH ON
MODELS
R-930AK
R-930AW
R-930AW
In the interest of user-safety the oven should be restored to its original
condition and only parts identical to those specified should be used.
TABLE OF CONTENTS
Page
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICE TO
AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY ...................INSIDE FRONT COVER
BEFORE SERVICING ...........................................................................................................................................1
MICROWAVE MEASUREMENT PROCEDURE ...................................................................................................2
FOREWORD.......................................................................................................................................................... 3
PRODUCT SPECIFICATIONS ..............................................................................................................................4
GENERAL INFORMATION................................................................................................................................... 4
OPERATION..........................................................................................................................................................6
TROUBLESHOOTING GUIDE ............................................................................................................................13
TEST PROCEDURE ............................................................................................................................................14
TOUCH CONTROL PANEL .................................................................................................................................21
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................................27
PICTORIAL DIAGRAM ........................................................................................................................................33
CONTROL PANEL CIRCUIT ...............................................................................................................................34
PRINTED WIRING BOARD .................................................................................................................................35
PARTS LIST ........................................................................................................................................................36
PACKING AND ACCESSORIES .........................................................................................................................39
SHARP ELECTRONICS CORPORATION
Service Headquarters: Sharp Plaza, Mahwah, New Jersey 07430-2135
R-930AK
R-930AW
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.
BEFORE SERVICING
Before servicing an operative unit, perform a microwave emission check as per the Microwave
Measurement Procedure outlined in this service manual.
If microwave emissions level is in excess of the specified limit, contact SHARP ELECTRONICS
CORPORATION immediately 1- (800) 237-4277.
If the unit operates with the door open, service person should 1) tell the user not to operate the oven
and 2) contact SHARP ELECTRONICS CORPORATION and Food and Drug Administration's
Center for Devices and Radiological Health immediately.
Service personnel should inform SHARP ELECTRONICS CORPORATION of any certified unit found
with emissions in excess of 4mW/cm2. The owner of the unit should be instructed not to use the unit
until the oven has been brought into compliance.
R-930AK
R-930AW
1
R-930AK
R-930AW
MICROWAVE MEASUREMENT PROCEDURE
A. Requirements:
1) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven
should not exceed 1mW/cm2 at any point 5cm or more from the external surface of the oven, measured prior to acquisition
by a purchaser, and thereafter (through the useful life of the oven), 5 mW/cm2 at any point 5cm or more from the external
surface of the oven.
2) Safety interlock switches
Primary interlock relay and door sensing switch shall prevent microwave radiation emission in excess of the requirement
as above mentioned, secondary interlock switch shall prevent microwave radiation emission in excess of 5 mW/cm2 at
any point 5cm or more from the external surface of the oven.
B. Preparation for testing:
Before beginning the actual measurement of leakage, proceed as follows:
1) Make sure that the actual instrument is operating normally as specified in its instruction booklet.
Important:
Survey instruments that comply with the requirement for instrumentation as prescribed by the performance standard
for microwave ovens, 21 CFR 1030.10(c)(3)(i), must be used for testing.
2) Place the oven tray in the oven cavity.
3) Place the load of 275±15 ml (9.8 oz) of tap water initially at 20±5˚C (68˚F) in the center of the oven cavity.
The water container shall be a low form of 600 ml (20 oz) beaker with an inside diameter of approx. 8.5 cm (3-1/2 in.)
and made of an electrically nonconductive material such as glass or plastic.
The placing of this standard load in the oven is important not only to protect the oven, but also to insure that any leakage
is measured accurately.
4) Set the cooking control on Full Power Cooking Mode
5) Close the door and select a cook cycle of several minutes. If the water begins to boil before the survey is completed,
replace it with 275 ml of cool water.
C. Leakage test:
Closed-door leakage test (microwave measurement)
1) Grasp the probe of the survey instrument and hold it perpendicular to the gap between the door and the body of the oven.
2) Move the probe slowly, not faster than 1 in./sec. (2.5 cm/sec.) along the gap, watching for the maximum indication on
the meter.
3) Check for leakage at the door screen, sheet metal seams and other accessible positions where the continuity of the metal
has been breached (eg., around the switches, indicator, and vents).
While testing for leakage around the door pull the door away from the front of the oven as far as is permitted by the closed
latch assembly.
4) Measure carefully at the point of highest leakage and make sure that the highest leakage is no greater than 4mW/cm2,
and that the secondary interlock switch does turn the oven OFF before any door movement.
NOTE: After servicing, record data on service invoice and microwave leakage report.
2
SERVICE MANUAL
CONVECTION
MICROWAVE OVEN
PRODUCT DESCRIPTION
R-930AK
R-930AW
R-930AK / R-930AW
FOREWORD
This Manual has been prepared to provide Sharp Electronics
Corp. Service Personnel with Operation and Service Information for the SHARP CONVECTION MICROWAVE OVENS R930AK / R-930AW.
It is recommended that service personnel carefully study the
entire text of this manual so that they will be qualified to render
satisfactory customer service.
Check the interlock switches and the door seal carefully.
Special attention should be given to avoid electrical shock and
microwave radiation hazard.
GENERAL INFORMATION
OPERATION
TROUBLESHOOTING GUIDE
AND TEST PROCEDURE
TOUCH CONTROL PANEL
COMPONENT REPLACEMENT AND
ADJUSTMENT PROCEDURE
WIRING DIAGRAM
SHARP ELECTRONICS CORPORATION
SHARP PLAZA, MAHWAH,
NEW JERSEY 07430-2135
PARTS LIST
3
R-930AK
R-930AW
SPECIFICATION
ITEM DESCRIPTION
Power Requirements 120 Volts
13.0 Amperes (Microwave) / 13.0 Amperes (Convection)
60 Hertz / Single phase, 3 wire grounded
Power Output 900 watts (IEC 705 Test Procedure)
Operating frequency of 2450MHz
Convection Power Output 1450 Watts
Case Dimensions Width 24-5/8" Height 14-7/8" Depth 19-1/8"
Cooking Cavity Dimensions
(1.5 Cubic Feet ) Width 16-1/8" Height 9-5/8" Depth 16-1/8"
Control Complement Touch Control System
Timer (0 - 99 min. 99 seconds)
Microwave Power for Variable Cooking
Repetition Rate;
P-HI...........................................Full power throughout the cooking time
P-90 .............................................................approx. 90% of Full Power
P-80 .............................................................approx. 80% of Full Power
P-70 .............................................................approx. 70% of Full Power
P-60 .............................................................approx. 60% of Full Power
P-50 .............................................................approx. 50% of Full Power
P-40 ..............................................................approx. 40% of Full Power
P-30 ..............................................................approx. 30% of Full Power
P-20 .............................................................approx. 20% of Full Power
P-10 ..............................................................approx. 10% of Full Power
P-0 ............................................. No power throughout the cooking time
Convection Temperature for Variable Cooking
CONVECTION.............................................. 100 - 450˚F Temp. control
LOW MIX. BAKE...............................350˚F with 10% microwave power
HIGH MIX. ROAST...........................300˚F with 30% microwave power
SLOW COOK..........................................300˚F for 4 hours (no preheat)
BROIL............................................................................450˚F (preheat)
CUSTOM HELP pad, SENSOR REHEAT pad, MINUTE PLUS pad, POPCORN pad
COMPU DEFROST pad, SENSOR COOK pad, COMPU BROIL pad
COMPU ROAST pad, COMPU BAKE pad, REHEAT pad, CONVEC pad
BROIL pad, SLOW COOK pad, HIGH MIX / ROAST pad, LOW MIX / BAKE pad
Number and temperature selection pads, KITCHEN TIMER pad, CLOCK pad
STOP/CLEAR pad, POWER LEVEL pad, START / TOUCH ON pad
Oven Cavity Light Yes
Safety Standard UL Listed FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J
GENERAL INFORMATION
GROUNDING INSTRUCTIONS
This oven is equipped with a three prong grounding plug. It must be plugged into a wall receptacle that is properly installed
and grounded in accordance with the National Electrical Code and local codes and ordinances.
In the event of an electrical short circuit, grounding reduces the risk of electric shock by providing an escape wire for the
electric current.
WARNING: Improper use of the grounding plug can result in a risk of electric shock.
4
R-930AK
R-930AW
Electrical Requirements
The electrical requirements are a 115 -120 volt 60 Hz, AC only,
15 or 20 amp. fused electrical supply. It is recommended that a separate
3-Pronged Plug
Grounded
Receptacle Box
circuit serving only this appliance be provided. When installing this
appliance, observe all applicable codes and ordinances.
A short power-supply cord is provided to reduce risks of becoming
entangled in or tripping over a longer cord.
Where a two-pronged wall-receptacle is encountered, it is the personal
responsibility and obligation of the customer to contact a qualified
Grounding Pin
electrician and have it replaced with a properly grounded three-pronged
wall receptacle or have a grounding adapter properly grounded and
polarized. If an extension cord must be used, it should be a 3-wire, 15
3-Pronged Receptacle
amp. or more cord. Do not drape over a countertop or table where it can
be pulled on by children or tripped over accidentally.
CAUTION: DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE ROUND GROUNDING PRONG FROM
THIS PLUG.
OVEN DIAGRAM
15
11 6
2
6
1. Ventilation openings. (Rear side)
2. Oven door with see-through window.
3. Oven lamp.
4. Turntable support.
5. Removable turntable.
The turntable will rotate clockwise or
counterclockwise.
6. Safety door latches.
The oven will not operate unless the door is
securely closed.
1
7
3
10
9
8
14
7. Wave guide cover.
8. Door open button.
9. Auto-Touch control panel.
10. Lighted digital display.
11. Convection air openings.
12. Removable low rack. (Broiling trivet)
13. Removable low rack. (Baking rack)
14. Turntable motor shaft.
15. Power supply cord.
5
12
13
4
TOUCH CONTROL PANEL
MIX CONV
DEFROST
SENSOR
Interactive
SENSOR
REHEAT
POPCORN
ELEVATE PKG
1 Baked potatoes
2 Frozen vegetables
3 Fresh veg-soft
4 Fresh veg-hard
5 Frozen entrees
6 Hot dogs
7 Bacon
8 Fish, seafood
COOK LBS OZ KG HELP
CUSTOM
HELP
MINUTE
PLUS
COMPU
DEFROST
SENSOR
COOKT
Convection
1 Hamburgers
2 Chicken pieces
3 Steaks
4 Fish steaks
1 Chicken
2 Turkey
3 Turkey breast
4 Pork
1 Bundt cake
2 Cookies
3 Muffins
4 French fries
COMPU
BROIL
COMPU
ROAST
COMPU
BAKE
PREHEAT CONVEC BROIL
SLOW
COOK
12345
100˚F 150˚F 275˚F 300˚F 325˚F
67890
350˚F 375˚F 400˚F 425˚F 150˚F
KITCHEN
TIMER
LOW MIX
BAKE
CLOCK
POWER
LEVEL
HIGH MIX
ROAST
ST OP
TCLEAR
START
TOUCH ON
5
R-930AK
R-930AW
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
The following is a description of component functions during
oven operation.
OFF CONDITION
Closing the door activates the door sensing switch and
secondary interlock switch. (In this condition, the monitor
switch contacts are opened.)
When oven is plugged in, 120 volts A.C. is supplied to the
control unit. (Figure O-1).
1. The display will show "SHARP SIMPLY THE BEST
PRESS CLEAR AND PRESS CLOCK".
To set any program or set the clock, you must first touch
the STOP/CLEAR pad. The display will clear, and " : "
will appear.
NOTE: When the door is opened, the oven lamp comes on.
2. A signal is input to the control unit, energizing the coil of
shut-off relay (RY-4). RY4 contacts close, completing a
circuit to the damper motor. The damper motor now
operates moving the damper to the open position, thereby
closing the contacts of the damper switch inputs a signal
to the control unit. The coil of relay RY-4 is de-energized,
opening its contacts, thereby turning off the damper
motor.
COOKING CONDITION
Program desired cooking time Variable Cooking Control by
touching the NUMBER pads and the power level pad. When
the START pad is touched, the following operations occur:
1. The contacts of relays are closed and components
connected to the relays are turned on as follows.
(For details, refer to Figure O-2)
RELAY CONNECTED COMPONENTS
RY-1 Oven lamp/Turntable motor
RY-2 Power transformer
RY-3 Heating element
RY-4 Damper motor
RY-5 Convevtion motor
RY-6 Fan motor
2. 120 volts A.C. is supplied to the primary winding of the
power transformer and is converted to about 3 volts A.C.
output on the filament winding, and approximately 2360
volts A.C. on the high voltage winding.
3. The filament winding voltage heats the magnetron
filament and the H.V. winding voltage is sent to a voltage
doubler circuit.
4. The microwave energy produced by the magnetron is
channelled through the waveguide into the cavity feedbox, and then into the cavity where the food is placed to
be cooked.
5. Upon completion of the cooking time, the power
transformer, oven lamp, etc. are turned off, and the
generation of microwave energy is stopped. The oven
will revert to the OFF condition.
6. When the door is opened during a cook cycle, monitor
switch, door sensing switch, the primary interlock relay
and the secondary interlock switch are activated with the
following results. The circuits to the turntable motor, the
cooling fan motor, and the high voltage components are
de-energized, the oven lamp remains on, and the digital
read-out displays the time still remaining in the cook
cycle when the door was opened.
7. The monitor switch is electrically monitoring the operation
of the primary interlock relay and the secondary interlock
switch and is mechanically associated with the door so
that it will function in the following sequence.
(1)When the door opens from a closed position, the primary
interlock relay and the secondary interlock switch open
their contacts, and then the monitor switch contacts
close.
(2) When the door is closed from the open position, the
monitor switch contacts first open, and then the contacts
of the primary interlock relay and the secondary interlock
switch close.
If the primary interlock relay and the secondary interlock
switch fail with their contacts closed when the door is
opened, the closing of the monitor switch contacts will form
a short circuit through the monitor fuse, primary interlock
relay and the secondary interlock switch, causing the monitor fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING
When Variable Cooking Power is programmed, the 120
volts A.C. is supplied to the power transformer intermittently
through the contacts of relay (RY-2). RY-2 is operated by
the control unit within an varying time base. Microwave
power operation is as follows:
VARI-MODE ON TIME OFF TIME
Power 10(P-HI) 32 sec. 0 sec.
(100% power)
Power 9(P-90) 30 sec. 2 sec.
(approx. 90% power)
Power 8(P-80) 26 sec. 6 sec.
(approx. 80% power)
Power 7(P-70) 24 sec. 8 sec.
(approx. 70% power)
Power 6(P-60) 22 sec. 10 sec.
(approx. 60% power)
Power 5(P-50) 18 sec. 14 sec.
(approx. 50% power)
Power 4(P-40) 16 sec. 16 sec.
(approx. 40% power)
Power 3(P-30) 12 sec. 20 sec.
(approx. 30% power)
Power 2(P-20) 8 sec. 24 sec.
(approx. 20% power)
Power 1(P-10) 6 sec. 26 sec.
(approx. 10% power)
Power 0(P-0) 0 sec. 32 sec.
(0% power)
Note: The ON/OFF time ratio does not correspond with
the percentage of microwave power, because
approx. 2 seconds are needed for heating of the
magnetron filament.
6
R-930AK
R-930AW
CONVECTION COOKING CONDITION
PREHEATING CONDITION
Program desired convection temperature by touching the
CONVECTION pad and the Temperature pad.
When the START pad is touched, the following operations
occur:
1. The coil of shut-off relays (RY1, RY3,RY5 and RY6) are
energized, the oven lamp, cooling fan motor, turntable
motor and convection motor are turned on.
2. The coil of relay (RY4) is energized by the control unit.
The damper is moved to the closed position, opening the
damper switch contacts. The opening of the damper
switch contacts sends a signal to the LSI on the control
unit de-energizing the relay (RY4) and opening the
circuit to the damper motor.
3. The coil of heater relay (RY3) is energized by the control
unit and the main supply voltage is applied to the heating
element.
4. When the oven temperature reaches the selected preheat
temperature, the following operations occur:
4-1 The heater relay is de-energized by the control unit
temperature circuit and thermistor, opening the
circuit to the heating element.
4-2. The oven will continue to function for 30 minutes,
turning the heater on and off, as needed to maintain
the selected preheat temperature. The oven will
shut-down completely after 30 minutes
CONVECTION COOKING CONDITION
When the preheat temperature is reached, a beep signal will
sound indicating that the holding temperature has been
reached in the oven cavity. Open the door and place the
food to be cooked in the oven.
Touch the CONVEC pad first and then touch the Temperature pad. And program desired cooking time by touching the
Number pads.
When the START pad is touched, the following operations
occur:
1. The numbers on the digital read-out start to count down
to zero.
2. The oven lamp, turntable motor, cooling fan motor and
convection motor are energized.
3. Heater relay (RY3) is energized (if the cavity temperature
is lower than the selected temperature) and the main
supply voltage is applied to the heating element to return
to the selected cooking temperature.
4. Upon completion of the cooking time, the audible signal
will sound, and oven lamp, turntable motor, cooling fan
motor and convection motor are de-energized. At the
end of the convection cycle, if the cavity air temperature
is above 275˚F, the circuit to RY6 will be maintained (by
the thermistor circuit) to continue operation of the cooling
fan motor until the temperature drops below 245˚F, at
which time the relay will be de-energized, turning off the
fan motor. Relay RY5 will however, open as soon as the
convection cycle has ended, turning off the convection
fan motor.
5. At the end of the convection cook cycle, shut-off relay
(RY4) is energized turning on the damper motor. The
damper is returned to the open position, closing the
damper switch contacts which send a signal to the
control unit, de-energizing shut-off relay (RY4).
AUTOMATIC MIX COOKING CONDITION
Touch the HIGH MIX/ROAST or the LOW MIX/BAKE pad
first. And then program desired cooking time by touching the
Number pads. The LOW MIX/BAKE pad is preprogrammed
for 350˚F with 10% microwave power, while the HIGH MIX/
ROAST pad is preprogrammed for 300˚F with 30% microwave power. When the START pad is touched, the following
operations occur:
1. The numbers on the digital read-out start to count down
to zero.
2. The shut-off relays (RY1,RY2,RY3,RY5 and RY6) are
energized, turning on the oven lamp, turntable motor,
cooling fan motor and convection fan motor.
3. The shut-off relay (RY4) is energized.
The damper door is closed from the open position.
4. The heater relay (RY3) is energized, applying the main
supply voltage to the heating element.
5. Now, the oven is in the convection cooking condition.
6. When the oven temperature reaches the selected
temperature, the following operations occur:
6-1. The power supply voltage is alternated to the heating
element and power transformer.
6-2. The heating element operates through the heater
relay (RY3) contacts and the power transformer
operates through the primary interlock relay (RY2)
contacts.
6-3. These are operated by the control unit to supply
alternately within a 32 second time base, convection
heat and microwave energy.
The relationship between the convection and microwave
power operations are as follows.
Note: The ON and OFF time ratio does not correspond
with the percentage of microwave power, because
approx. 2 seconds are needed for heating of the
magnetron filament.
26 SEC.6 SEC.
(MICRO.)
(CONVEC.)
(MICRO.)
(CONVEC.)
ON
OFF
LOW MIX
BAKE
12 SEC. 20 SEC.
ON
OFF
ON
OFF
32 SEC.
HIGH MIX
ROAST
MICROWAVE POWER
= APPROX. 10%
CONVECTION
TEMPERATUE
= 350˚F (180˚C)
MICROWAVE POWER
= APPROX. 30%
CONVECTION
TEMPERATUE
Note: During alternate Microwave/Convection operation,
the convection heater is energized only if the cavity
temperature drops below the set temperature.
SENSOR COOKING CONDITION
Using the SENSOR COOK function, the foods are cooked
without figuring time, power level or quantity. When the oven
senses enough steam from the food, it relays the information to its microprocessor which will calculate the remaining
cooking time and power level needed for best results.
When the food is cooked, water vapor is developed.
7
= 300˚F
R-930AK
R-930AW
The sensor “senses” the vapor and its resistance increases
gradually. When the resistance reaches the value set according to the menu, supplementary cooking is started.
The time of supplementary cooking is determined by experiment with each food category and inputted into the LSI.
An example of how sensor works:
1. Potatoes at room temperature.
Vapor is emitted very slowly.
MICROWAVE
2. Heat potatoes. Moisture and
humidity is emitted rapidly.
You can smell the aroma as it
cooks.
3. Sensor detects moisture and
humidity and calculates
AH SENSOR
MICROWAVE
cooking time and variable
power.
Cooking Sequence.
1. Touch SENSOR COOK pad.
NOTE: The oven should not be operated on SENSOR
COOK immediately after plugging in the unit. Wait
two minutes before cooking on SENSOR COOK.
2. Select desired Sensor setting.
3. Touch START pad.
The coil of shut-off relay (RY1, RY6) is energized, the
oven lamp and cooling fan motor are turned on, but the
power transformer is not turned on.
4. After about 16 seconds, the cook relay (RY-2) is
energized. The power transformer is turned on,
microwave energy is produced and first stage is started.
The 16 seconds is the cooling time required to remove
any vapor from the oven cavity and sensor.
NOTE: During this first stage, do not open the door or touch
STOP/CLEAR pad.
5. When the sensor detects the vapor emitted from the
food, the display switches over to the remaining cooking
time and the timer counts down to zero. At this time, the
door may be opened to stir food, turn it or season, etc.
6. When the timer reaches zero, an audible signal sounds.
The shut-off relay and cook relay are de-energized and
the power transformer, oven lamp, etc. are turned off.
7. Opening the door or touching the STOP/CLEAR pad, the
time of day will reappear on the display and the oven will
revert to an OFF condition.
COMPU BROIL/ COMPU ROAST/ COMPU BAKE
COMPU BROIL/ ROAST/ BAKE will automatically compute
the oven temperature, microwave power and cooking time
for baking, roasting and broiling. Set the desired program by
touching the COMPU BROIL/ ROAST/ BAKE pad, and
number pad. Enter the weight by touching the Number pads.
When the START pad is touched, the following operations
occur:
1. The COOK indicator will light and the Convection Fan
Symbol will rotate.
2. The cooking time will appear on the display and start
counting down to zero. The cooking time is adjusted
automatically according to the weight of the food.
3. The shut-off relays (RY1, RY5 and RY6) are energized,
turning on the oven lamp, turntable motor, cooling fan
motor and convection motor. The power supply voltage
is applied to the heating element.
4. Now, the oven is in the convection cooking mode.
5. When the oven temperature has reached the programmed
convection temperature, the oven goes into the
programmed cooking mode.
6. At the end of the COMPU BROIL/ ROAST/ BAKE cycle,
the damper is returned to the open position and the oven
will go to the off condition. The cooling fan will remain on
until the oven has cooled.
COMPU DEFROST COOKING
The COMPU DEFROST key is a special function key to
defrost meats and poultry faster and better. COMPU DEFROST automatically defrosts roast beef, etc.. When the
COMPU DEFROST is selected and the food weight is
entered by using the COMPU DEFROST pad, the oven will
cook according to the special cooking sequence.
FIRE SENSING FEATURE (MICROWAVE MODE)
This model incorporates a sensing feature which will stop
the oven's operation if there is a fire in the oven cavity during
microwave cooking.
This is accomplished by the LSI repeatedly measuring the
voltage across the temperature measurement circuit (thermistor) during it's 32-seconds time base comparing the
obtained voltage measurements. If the most recent voltage
measured is 300mV greater than the previous voltage
measured, the LSI judges it as a fire in the oven cavity and
switches off the relays to the power transformer, fan motor
and convection motor. The LSI also stops counting down
and closes the damper door so that no fresh air will enter the
oven cavity. Please refer to the following section for a more
detailed description.
Operation
Please refer to the timing diagrams below.
1. The thermistor operates within a 32-seconds time base
and it is energized for three (3) seconds and off for 29
seconds. Two (2) seconds after the thermistor is
energized, the voltage across the temperature
measurement circuit is sampled by the LSI and twenty
one (21) seconds after the thermistor is cut off the LSI
turns on the cooling fan for six (6) seconds.
2. The above procedure is repeated. If the difference
between the first voltage measured (in step 1) and the
voltage measured when the procedure is repeated (step
2) is greater than 300mV the LSI makes the judgment
that there is a fire in the oven cavity and will switch off the
relays to the power transformer, fan motor and convection
motor. The LSI also stops counting down and closes the
damper door so that no fresh air will enter the oven
cavity.
3. Once the fire sensor feature has shut the unit down, the
programmed cooking cycle may be resumed by pressing
the "START" pad or the unit may be reset by pressing the
"CLEAR" pad.
CONVECTION
THERMISTOR
8
MOTOR
Sensing
Voltage
3
0 2 24 30 64 (sec.)
ON
OFF
3 sec.
ON
OFF
ON
OFF
Sensing the voltage across the temperature measurement circuit.
6 sec.
32 (sec.)
R-930AK
R-930AW
IMPORTANT:
During sensor cooking operation, the fire sensing operation sequence will not begin until the AH sensor has
SCHEMATIC DIAGRAM
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. CLOCK APPEARS ON DISPLAY.
MAGNETRON
TEMPERATURE
FUSE
TTM
TURNTABLE MOTOR
FM
OL
OVEN LAMP
FAN MOTOR
CM
CONVECTION MOTOR
DM
A-7
DAMPER MOTOR
A-9
A-1
CONTROL UNIT
AH SENSOR
RY4
A-3
DOOR
SENSING
SWITCH
FUSE
OUTER
CASE
SWITCH
120V
60Hz
OUTER
CASE
SWITCH
CONV.
THERMAL
CUT-OUT
SECONDARY
INTERLOCK
SWITCH
detected vapors and initiated a sensor cooking cycle.
This is because the operation of the convection fan
would interfere with the AH sensor's vapor detection.
POWER
TRANSFORMER
CAPACITOR
0.94µ
RY5
RY3
A-5
RY6
THER-
MISTOR
RY2
COM.
(RY1)
RY1
RY2
PRIMARY
INTERLOCK
RERAY
E-5E-4E-3E-2E-1F-3F-2F-1
E-6
DAMPER
SWITCH
N.O.
(RY1)
COM.
(RY3)
COM.
(RY2)
N.O.
(RY2)
N.O.
(RY3)
MONITOR SWITCH
HEATIMG ELEMENT
MAGNETRON
H.V. RECTIFIER
1. DOOR CLOSED.
SCHEMATIC
2. COOKING TIME PROGRAMMED.
3. “START” PAD TOUCHED.
MAGNETRON
TEMPERATURE
FUSE
TTM
TURNTABLE MOTOR
FM
OL
OVEN LAMP
FAN MOTOR
CM
CONVECTION MOTOR
FUSE
OUTER
CASE
SWITCH
120V
60Hz
OUTER
CASE
SWITCH
CONV.
THERMAL
CUT-OUT
SECONDARY
INTERLOCK
SWITCH
Figure O-1. Oven Schematic-OFF Condition
COM.
RY6
THER-
MISTOR
RY2
(RY1)
RY1
RY2
PRIMARY
INTERLOCK
RERAY
E-5E-4E-3E-2E-1F-3F-2F-1
E-6
DAMPER
SWITCH
DM
A-7
DAMPER MOTOR
A-9
A-1
CONTROL UNIT
AH SENSOR
RY4
A-3
DOOR
SENSING
SWITCH
A-5
RY5
RY3
N.O.
(RY1)
COM.
(RY3)
COM.
(RY2)
N.O.
(RY2)
N.O.
(RY3)
MONITOR SWITCH
HEATIMG ELEMENT
POWER
TRANSFORMER
CAPACITOR
0.94µ
MAGNETRON
H.V. RECTIFIER
Figure O-2. Oven Schematic-Microwave Cooking Condition
9
R-930AK
R-930AW
1. DOOR CLOSED.
SCHEMATIC
2. MIX COOKING PAD TOUCHED.
3. COOKING TIME PROGRAMMED.
4. “START” PAD TOUCHED.
5. RY2 AND RY3 WILL ALTERNATELY CLOSE.
DURING COOK CYCLE.
MAGNETRON
TEMPERATURE
FUSE
TTM
TURNTABLE MOTOR
FM
OL
OVEN LAMP
FAN MOTOR
CM
CONVECTION MOTOR
DM
A-7
DAMPER MOTOR
A-9
FUSE
OUTER
CASE
SWITCH
120V
60Hz
OUTER
CASE
SWITCH
CONV.
THERMAL
CUT-OUT
SECONDARY
INTERLOCK
SWITCH
A-1
CONTROL UNIT
AH SENSOR
RY4
A-3
DOOR
SENSING
SWITCH
RY5
RY3
A-5
RY6
THER-
MISTOR
RY2
COM.
(RY1)
RY1
RY2
PRIMARY
INTERLOCK
RERAY
E-5E-4E-3E-2E-1F-3F-2F-1
E-6
DAMPER
SWITCH
N.O.
(RY1)
COM.
(RY3)
COM.
(RY2)
N.O.
(RY2)
N.O.
(RY3)
MONITOR SWITCH
HEATIMG ELEMENT
POWER
TRANSFORMER
CAPACITOR
0.94µ
MAGNETRON
H.V. RECTIFIER
Figure O-3. Oven Schematic-Automatic Mix Cooking Condition
1. DOOR CLOSED.
2. CONVECTION PAD TOUCHED.
3. DESIRED TEMP. TOUCHED.
4. COOKING TIME PROGRAMMED.
5. “START” PAD TOUCHED.
FUSE
OUTER
CASE
SWITCH
120V
60Hz
OUTER
CASE
SWITCH
SCHEMATIC
CONV.
THERMAL
CUT-OUT
SECONDARY
INTERLOCK
SWITCH
MAGNETRON
TEMPERATURE
FUSE
TTM
TURNTABLE MOTOR
FM
OL
OVEN LAMP
FAN MOTOR
CM
CONVECTION MOTOR
DM
A-7
DAMPER MOTOR
A-9
A-1
CONTROL UNIT
AH SENSOR
RY4
A-3
DOOR
SENSING
SWITCH
RY5
RY3
A-5
RY6
THER-
MISTOR
RY2
COM.
(RY1)
RY1
RY2
PRIMARY
INTERLOCK
RERAY
E-5E-4E-3E-2E-1F-3F-2F-1
E-6
DAMPER
SWITCH
N.O.
(RY1)
COM.
(RY3)
COM.
(RY2)
N.O.
(RY2)
N.O.
(RY3)
MONITOR SWITCH
HEATIMG ELEMENT
POWER
TRANSFORMER
CAPACITOR
0.94µ
MAGNETRON
H.V. RECTIFIER
Figure O-4. Oven Schematic-Convection Cooking Condition
10
OUTER CASE
CABINET
OUTER CASE
SWITCHES
ACTUATOR
This outer case mounting screw is
pushing the actuator.
DESCRIPTION AND FUNCTION OF COMPONENTS
R-930AK
R-930AW
DOOR SENSING AND SECONDARY INTERLOCK
SWITCHES
The door sensing switch in the primary interlock system is
mounted in the upper position on the latch hook, the
secondary interlock switch is mounted in the lower position
on the latch hook. They are activated by the latch heads on
the door. When the door is opened, the switches interrupt
the circuit to all components. A cook cycle cannot take place
until the door is firmly closed thereby activating both interlock switches. The primary interlock system consists of the
door sensing switch and primary interlock relay located on
the control circuit board.
DOOR SENSING
SWITCH
MONITOR FUSE
MONITOR SWITCH
SECONDARY
INTERLOCK
SWITCH
OUTER CASE SWITCHES
The two outer case switches are mounted near the power
supply cord at the oven cavity rear plate. When the outer
case cabinet is installed with the screws, one of the screws
pushes the actuator and then the actuator pushes each
plungers of the two outer case switches and their contacts
are closed. When a cabinet mounting screw which is pushing the actuator is removed, the two outer case switches
interrupt the circuit to the all components.
WARNING
The circuit to all components can be connected to the
power supply without the outer case cabinet by reinstalling the cabinet mounting screw. BUT AT THAT TIME,
NEVER TOUCH ANY PARTS OF THE HIGH VOLTAGE
CIRCUIT TO AVOID ELECTROCUTION.
Figure D-1. Door sensing switch, monitor switch and
secondary interlock switches
MONITOR SWITCH
The monitor switch is mounted on the middle position of
latch hook. It is activated (the contacts opened) by the lower
latch head while the door is closed. The switch is intended
to render the oven inoperative by means of blowing the
monitor fuse when the contacts of the primary interlock relay
and secondary interlock switch fail to open when the door is
opened.
Functions:
1. When the door is opened, the monitor switch contact
close (to the ON condition) due to their being normally
closed. At this time the door sensing and secondary
interlock switches are in the OFF condition (contacts
open) due to their being normally open contact switches.
2. As the door goes to a closed position, the monitor switch
contacts are first opened and then the door sensing
switch and the secondary interlock switch contacts close.
(On opening the door, each of these switches operate
inversely.)
3. If the door is opened, and the primary interlock relay and
secondary interlock switch contacts fail to open, the
monitor fuse blows simultaneously with closing of the
monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN MONITOR
FUSE TEST THE DOOR SENSING SWITCH,
PRIMARY INTERLOCK RELAY, SECONDARY
INTERLOCK SWITCH AND MONITOR
SWITCH FOR PROPER OPERATION. (REFER TO CHAPTER “TEST PROCEDURE”).
NOTE: MONITOR FUSE AND MONITOR SWITCH ARE
REPLACED AS AN ASSEMBLY.
THERMISTOR
The thermistor is a negative temperature coefficient type.
The temperature in the oven cavity is detected through the
resistance of the thermistor, and then the control unit
causes the heater relay to operate, thus the current to the
heating element is turned ON/OFF.
MAGNETRON TEMPERATURE FUSE.
The temperature fuse located on the waveguide is designed
to prevent damage to the magnetron if an over heated
condition develops in the megnetron due to cooling fan
failure, obstructed air guide, dirty or blocked air intake, etc.
Under normal operation, the temperature fuse remains
closed. However, when abnormally high temperatures are
reached within the magnetron, the temperature fuse will
open at 302˚F(150˚C) causing the oven to shut down.
CONV. THERMAL CUT-OUT
The thermal cut-out located on the left side of the thermal
protection plate (left) is designed to prevent damage to the
heater unit if an over heated condition develops in the
heating unit due to convection fan failure, thermistor failure,
obstructed air ducts, dirty or blocked air intake, etc.
Under normal operation, the thermal cut-out remains closed.
However, when abnormally high temperatures are reached
within the heater unit, the thermal cut-out will open at
302˚F(150˚C) causing the oven to shut down.
When the thermal cut-out has cooled, the thermal cut-out
closes at 266˚F(130˚C).
11
R-930AK
R-930AW
HEATING ELEMENT
The heating element is located at the left side of the oven
cavity. It is intended to heat air driven by the convection fan.
The heated air is kept in the oven and force-circulated and
reheated by the heating element.
CONVECTION COOKING SYSTEM
This oven is designed with a hot air heating system where
food is not directly heated by the heating element, but is
heated by forced circulation of the hot air produced by the
heating element.
The air heated by the heating element is circulated through
the convection passage provided on the outer casing of the
oven cavity by means of the convection fan which is driven
by the convection motor. It then enters the inside of the oven
through the vent holes provided on the left side of the oven.
Next, the hot air heats the food on the turntable and leaves
the oven cavity through the vent in the center of the oven
cavity left side wall.
Without leaving the oven, this hot air is reheated by the
heating element, passes through the convection passage
and enters the inside of the oven cavity again, in a continuing cycle.
In this way, the hot air circulates inside the oven cavity to
raise its temperature and, at the same time, comes into
contact with the food being cooked.
When the temperature inside the oven cavity reaches the
selected temperature, the heating element is de-energized.
When the temperature inside the oven cavity drops below
the selected temperature, the heating element is energized
again. In this way, the inside of the oven cavity is maintained
at approximately the selected temperature.
When the convection time reaches 0, the heating element is
de-energized and the convection fan stops operating and
the oven shuts off.
Damper is in the closed position, so that no hot air will be
allowed to leak out the oven cavity.
Damper Operation
1. When power supply cord is plugged in:
1-1. When power supply cord is plugged in, a signal is
sensed in the control unit, and operates shut-off
relay (RY4).
1-2. Contacts of shut-off relay (RY4) close, the damper
motor is energized, opening the damper door.
1-3. When the damper is moved to the open position by
the damper cam the damper switch is closed (ON
position).
1-4. The signal from damper switch is re-sensed in the
control unit and shut-off relay (RY4) is turned off.
1-5. The 120 volts A.C. to the damper motor is removed
and the motor turns off.
2. When oven is microwave cooking:
Damper is in the open position.
3. When oven is convection cooking:
3-1. Damper motor is energized by touching the
convection, temperature and START pads.
3-2. When damper is in the closed position (damper
switch is OFF), its signal is sensed by the control
unit, and shut-off relay (RY4) is de-energized.
3-3. The damper is held in the closed position during the
convection cooking operation.
3-4. At the end of the convection cooking, shut-off relay
(RY4) is energized, and the damper is returned to
the open position.
NOTE: If the damper door is not in the proper position,
closed during convection or open during microwave,
the control unit will stop oven operation after 1
minute.
DAMPER OPEN-CLOSE MECHANISM
DAMPER SHAFT
Usually, the damper is in the open position except during
convection cooking. Damper position is set automatically by
damper motor, damper switch, motor cam and damper
shaft. These components are operated by a signal that
judges if microwave cooking or convection cooking operation is selected by the control unit.
DAMPER DUCT
DAMPER
Microwave Cooking:
Damper is in the open position, because a portion of cooling
air is channelled through the cavity to remove steam and
vapors given off from the heating foods.
It is then exhausted at the top of the oven cavity into a
DAMPER CAM
DAMPER SWITCH
DAMPER MOTOR
condensation compartment.
Convection Cooking:
Figure D-2. Damper Mechanism
TROUBLESHOOTING GUIDE
When troubleshooting the microwave oven, it is helpful to follow the Sequence of Operation in performing the checks. Many
of the possible causes of trouble will require that a specific test be performed. These tests are given a procedure letter which
will be found in the “Test Procedure”section.
IMPORTANT: If the oven becomes inoperative because of a blown monitor fuse, check the monitor switch, primary interlock
relay, door sensing switch and secondary interlock switch before replacing the monitor fuse. If monitor fuse
is replaced, the mintor switch must olso be replaced at the same time. Use part FFS-BA012WRK0 as an
assembly.
12
Loading...