Sharp r-8580 User Manual
SHARP SERVICE MANUAL
S9706R8580J//
CONVECTION
MICROWAVE OVEN
TAME OF CONTENTS
PRECAUTIONS
FOREWORD
THUMB INDEX
PRODUCT DESCRlPTlON
OPERATION
SERVlClNG
TOUCH CONTROL PANEL ASSEMBLY
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
MICROWAVE MEASUREMENT PROCEDURE
PICTORIAL DIAGRAM
CONTROL PANEL CiRCUlT
PRlNTED WIRING BOARD
PARTS LIST
PACKING AND ACCESSORIES
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SHARPCORPORATION
SERVICE MANUAL
R -8680
SHARP
CONVECTION MICROWAVE OVEN
R-8580
FOREWORD
This Manual has been prepared to provide Sharp Corp. Service
Personnel with complete Operation and Service Information for
the SHARP CONVECTION MICROWAVE oven, R-8580.
It is recommended that service personnel carefully study the
entire text of this manual so they will be qualified to render
satisfactory customer service.
Check interlock switches and door seal carefully. Special at-
tention should be given to avoid electrical shock and microwave
radiation hazard.
CAUTION
MICROWAVE RADIATION
(RD36102U)
PRODUCT DESCRIPTION
Personnel should not ,be exposed to the microwave energy
which ‘may radiate from the magnetron or other microwave
generating devices if it is improperly used or connected. All
input and output microwave connections, waveguides,flanges
and gaskets must be secured. Never operate the device without
a microwave energy absorbing load attached. Never look into
an open waveguide or antenna while the device is energized.
Note( Parts List)
: The parts marked ,,+I’ are used in voltage
more than 25OV.
(RD36202U)
SHARPCORPORATK)N
OSAKA, JAPAN
(RD37201 U)
1
R-8580
PRODUCT DESCRIPTION
SPECIFICATION
ITEM
Power Requirements
Power Consumption
Power Output
Convection Heater Power Output
Case Dimensions
Cooking Cavity Dimensions
Control Complement
Set Weight
DESCRIPTION
240 Volts
50 Hertz
Single phase, 3 wire earthed
14OOW (Microwave)
1600W (Convection)
700 watts normal of RF microwave energy (2 liter water load)
Operating frequency of 2450M Hz
1.500 Watts
Width 627mm
Height 407mm
Depth 500mm
Width 395mm
Height 253mm
Depth 422mm
Touch Control System
Clock( I:00 - 12:59 )
Timer (0 - 99 min. 99sec. )
Microwave Power for Variable Cooking
Repetition Rate;
HIGH
MED HIGH
MED
MED LOW (DEFROST)
LOW ,......,............*....
HOLD
Convection Temperature Contro
40 “C - 250 “C
AUTO START COOKING
INSTANT COOKING
EASY DEFROST COOKING
CONVECTION COOKING
SENSOR COOKING
AUTO MATIC MIX COOKING
COMPU COOKING
Approx. 31 .O kg
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . ..*.................................
. . . ..*............................,.,..................
.,.....*......................
Full power throughout the cooking time
approx. 70% of Full Power
approx. 50% of Full Power
. . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
No power throughout the cooking time
Ii’Range;
approx. 30% of Full Power
approx. 10% of Full Power
Auto-TouchTM Control Panel
,&&:::C::P:
1 - Fresh vegetables
2 - Frozen vegetables
3 - Baked potatoes
4 - Frozen dinners
5 - Bacon
6 - Chicken preces
7 - Fish fillets
6 - Rice 8 Pasta
9 - Cake
0 - Reheat
I 6
i
180°C
7 200%
TIMER
HOLD
-Roast beef/lamb
1
2 - Roast pork
- Roast chrcken
3
- Roast turkey
4
-Roast dmner
5
- Mixed grill
6
-Grilled chicken
7
- Bread loaves
6
-Cake layers
9
0 - Biscuits
4
II
AUTO START
CLOCK
-.
1 ’
I
Touch to select sensor cook mode
Touch to select Compu Cook mode
.EASY DEFROST PAD
Touch to defrost meat by
weight only
INSTANT COOK PAD
Touch once to cook for 1
increase by 1 minute mult
this pad is touched during
cooking.
NUMBER AND TEMPERATURE PADS
Touch to enter cooking times, clock time,
convection temperature or to select the
Sensor or Compu Cook categories.
CONVECTION COOKING FUNCTION PADS
Touch to cook for each function
VARIABLE COOKING CONTROL PADS
Touch to select microwave power setting. If
not touched, HIGH is automatically selected.
Touch to select food doneness setting for
Compu Cook. If not touched, Med Done is
automatically selected.
TIMER/HOLD PAD
/
Touch to set minute timer or HOLD function
-AUTO START/CLOCK PAD
Touch to set clock or auto start time
,---STOP/CLEAR PAD
Touch to erase during programming.
Touch once to stop operation of oven during
cooking;, touch twice to cancel cooking
R-8580
entering
minute at HIGH or
:iples each time
HIGH/VARIABLE
Touch to start oven after setting programme.
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
The following is a description of component functions
during oven operation.
OFF CONDITION
Closing the door
switches: upper latch switch, lower latch switch and
stop switch.
(In this condition, the monitor switch
contacts are opened.)
When oven is plugged in, 240 volts A.C. is supplied to
the relay unit. (Figure O-l).
1. The display will show flashing “88:88”.
To set any program or set the clock;- you must first
touch the STOP/CLEAR pad. The display will clear,
and I:00 will appear and count up every minute.
Note: When the door is opened, the oven lamp comes
2. A si;al is input to the control unit, energizing the
coil of shut-off relay (RY6).
RY6 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 RY6 is de-energized, opening its
contacts, thereby turning off the damper motor.
activates both door interlock
COOKING CONDITION
HIGH COOKING
Program desired cooking time and Variable Cooking
Control by touching the NUMBER pads and the HIGH
pad of the Variable Cooking Control. When the START
pad is touched, the following operations occur:
The contacts of relays are closed and components
1.
connected to the relays are turned on as follows.
(For details, refer to Figure O-2)
RELAY
RY-1
RY-2
RY-3
RY-4
RY-5
RY-6
2.
240 volts A.C. is supplied to the primary winding
of the power transformer and is converted to about
3.3 volts A.C. output on the filament winding, and
approximately 2043 volts A.C. on the high voltage
winding.
The filament winding voltage heats the magnetron
3.
filament and the H.V. winding voltage is sent to a
voltage doubler circuit.
The microwave energy produced by the magnetron
4.
is channeled through the waveguide into the cavity
feed-box, and then into the cavity where the food
is placed to be cooked.
CONNECTED COMPONENTS
power transformer
oven lamp/turntable motor
convection motor
convection heater
fan motor
damper motor
(RD71101 U)
’
(RD71207U)
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, upper latch switch, lower latch
switch and stop switch. are activated with the following results. The circuits to the turntable motor,
the cooling fan motor, and the high voltage components are deenergized, the oven lamp remains on,
and the digital readout displays the time still remaining in the cook cycle when the door was
opened.
The monitor switch is electrically monitoring the
7 .
operation of the upper latch switch and is mechan-
ically associated with the door so that it will function in the following sequence.
(1) When the door opens from a closed position,
the upper latch switch and lower latch switch
open their contacts, and then the monitor
switch contacts close.
(2) When the door is closed from the open posi-
tion, the monitor switch contacts first open,
and then the contacts of the upper latch switch
and lower latch switch close.
the common and normal open contacts of upper
If
latch 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 fuse and
upper latch switch, causing the monitor fuse to blow.
MED HIGH, MED, MED LOW (DEFROST), LOW,
HOLD COOKING
When Variable Cooking Power is programed, the 240
volts A.C. is supplied to the power transformer
intermittently through the contacts of relay( RY-2)
which is operated by the control unit within a 32 sec-
ond time base. Microwave power operation is as fol-
lows:
VARI-MODE
HIGH
(100% power)
MED HIGH
(approx. 70% power)
MED
(approx. 50% power)
MED LOW (DEFROST)
(approx. 30% power)
LOW
(approx. 10% power)
HOLD
(0% power)
ON TIME
32 sec.
24 sec.
18 sec.
12 sec.
6 sec. 26 sec.
0 sec.
OFF TIME
0 sec.
8 sec.
14 sec.
20 sec.
32 sec.
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.
(RD71401 U)
R -8580
CONVECTION COOKING CONDITION
PREHEATING CONDITION
Program desired convection temperature by touching
the CONVECTION pad and the temp. pad.
When the START pad is touched, the following operations occur:
1. The coil of shut-off relays (RY2, RY3 and RY5) are
energized, the oven lamp, cooling fan motor,
turntable motor and convection motor are turned
2. y:k coil of relay (RY6) is energized by the CPU
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 CPU unit de-energizing
the relay (RY6) and opening the circuit to the
damper motor.
3. The coil of heater relay (RY4) is energized by the
CPU unit and the main supply voltage is added to
the convection heater.
4. When the oven temperature reaches the selected
preheat temperature, the following operations oc-
cur:
4-l. The heater relay (RY4) is de-energized by
the CPU unit temperature circuit and
thermistor, opening the circuit to the convection heater.
4-2. The oven will continue to function for 15
minutes, turning the convection heater on
and off, as needed to maintain the selected
preheat temperature.
The oven will shut-down completely after
15 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.
Program desired cooking time and convection temperature by touching the NUMBER pad, CONVECTION
pad and Temperature pad.
When the START pad is touched, the following operations occur:
1.
The numbers of the digital readout. start the count
down to zero.
2.
The oven lamp, turntable motor, cooling fan motor
and convection motor are energized.
Heater relay (RY4) is energized (if the cavity tem-
3.
perature is lower than the selected temperature)
and the main supply voltage is applied to the convection heater 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 118 OC., the
circuit to RY5 will be maintained (by the thermistor
circuit) to continue operation of the cooling fan
motor until the temperature drops below 118 OC.,
at which time the relay will be de-energized, turning off the fan motor. Relay RY3 will however,
open as soon as the convection cycle has ended,
turning off the convection fan motor.This will now
cool and allow the damper door to open.
5. At the end of the convection cook cycle, shut-off
relay (RY6) 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 (RY6).
AUTOMATIC MIX COOKING CONDITION
Program desired cooking time and temperature by
touching the number pads and the LOW MIX/BAKE
or HIGH MIX/ROAST pad
When the START pad is touched, the following operations occur:
1.
The numbers of the digital readout start the count
down to zero.
2.
The shut-off relay (RY2, RY3 and RY5) are energized, turning on the oven lamp, turntable motor,
and cooling fan motor.
3.
The shut-off relay (RY6) is energized.
The damper door is closed from the open position.
4.
The heater relay (RY4) is energized, adding the
mains supply voltage to the convection heater.
5.
Now, the oven is in the convection cooking condition.
6.
When the oven temperature reaches the selected
temperature, the following operations occur:
6-l. The power supply voltages is added to the
convection heater and power transformer alternately.
6-2. The convection heater operates through the
heater relay (RY4) contacts and the power
transformer operates through the cook relay
(RYI ) contacts.
6-3. These are operated by the CPU unit to sup-
ply alternately within a 32 second time base,
convection heat and microwave energy.
The relationship between the
wave power operations are as
convection
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.
MICROWAVE POWER
- Appmx. 10%
I
ICONVECJ
1
im
I
r
t
OFF
‘ON
I
I I
&gjggg&
32~
HIGH MIX
-ROAST
CONVECTION
TEMPERATURE
I
I
MICROWAVE POWER
CONVECTION
TEMPERATURE
i
- leo°C
- A6wrcuc. 30%
-200%
and
micro-
R-8580
Note: During alternate Microwave/Convection opera-
tion, 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.
The sensor “senses” the vapor and its resistance increases gradually. When the resistance reaches the
value set according to the menu, supplementary cook-
ing 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. Broccoli at room temperature.
Vapor is emitted very slowly.
2. Heat broccoli. Moisture and humidity is emitted
rapidly. You can smell the aroma as it cooks.
3. Sensor detects moisture and humidity and calcu-
lates cooking time and variable power.
Cooking Sequence.
1. Touch SENSOR COOK pad.
NOTE:The oven should not be operated on SEN-
SOR COOK immediately after plugging in
the unit. Wait five minutes before cooking
on SENSOR COOK.
2.
Select desired Sensor setting.
3. Touch START pad.
The coil of shut-off relays(RY2,RY5) are 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 (RYI) 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.
When the timer reaches zero, an audible signal
6.
sounds. The shut-off relay and cook relay are
de-energized and the power transformer, oven
lamp, etc. are turned off,
Opening the door or touching the STOP/CLEAR
7.
pad, the time of day will reappear on the display
and the oven will revert to an OFF condition.
COMPU COOK
COMPU COOK will automatically compute the oven
temperature, microwave power and cooking time for
baking, roasting and broiling.
Set the desired program by touching the COMPU
COOK 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.
The shut-off relays (RY2, RY3, RY4 and RY5) are
3.
energized, turning on the oven lamp, turntable
motor, cooling fan motor and convection motor.
The power supply voltage is added to the con-
vection heater.
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 COOK 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.
EASY DEFROST COOKING
The EASY DEFROST key is a special function key to
defrost meats and poultry faster and better.
EASY DEFROST key has 4 defrost stages.
EASY DEFROST automatically defrosts roast beef, etc.
When EASY DEFROST is selected and the food weight
is entered by using the number pads, the oven will
cook according to the special cooking sequence.
240V-50Hz
G-4
MBA
AC CORD CONNECTION
BRN BROWN
BLU : BLUE
G-Y GREEN AND
YELLOW STRIPE
I17 : SECTIONAL AREA
OF l.Omm’ MIN.
1 DOOR CLOSE0
LOWER
LATCH
SWITCH
MONITOR RESISTOR O.B/2OW MON,TOR SW,TCH
OVEN LAMP
FAN MOTOR
n
RELAY-UNIT A-3
-______
DAMPER MOTOR
-
CONVECTION HEATER
TURNTABLE MOTOR
TEMP.
FUSE
142’C
UPPER
LATCH
SWITCH
NC
?
AC CORD CONNECTION
BRN BROWN
BLU BLUE
G-Y GREEN AND
YELLOW STRIPE
/I7
SECTIONAL AREA
OF l.Omm’ MIN
SENSOR COOKING
NOTE CONDITION
1 DOOR CLOSED
2 ‘SENSOR COOK”
PAD TOUCHED
3 START’ PAD
HIGH COOKING
1 DOOR CLOSED
2 COOKING TIME
PROGRAMMED
3 VARIABLE COOKING
LOWER
I ATI
-. -. .
SWITCH
I,
I
d ^-^^
MONITOR RESISTOR D.B/2DW
OVEN LAMP
CONVECTION%EATER
RELAY-UNIT
-_-
MONITOR SWITCH
w. +A-7
I i
RW
l-6
A
RV6
A-5
I
1
-
c
TEMP.
FUSE
142’C
I
UPPER
LATCH
SWITCH
NC
I
; POWER TRANSFORMER
I 1
HIGH VOLTAGE
RECTIFIER
MAGNETRON
A
Figure O-l. Oven Schematic-OFF Condition
I
RECTIFIER ,
POWER TRANSFORMER
I
HIGH VOLTAGE
RECTIFIER
t
MAGNETRON
Figure O-2. Oven Schematic-High and Sensor Cooking Condition
R-8580
240V-50Hz
MONITOR RESISTOR 0.8/20W MONITOR SWITCH
OVEN LAMP
a//o
TEMP.
FUSE
142°C
I
AC CORD CONNECTION
BRN : BROWN
BLU : BLUE
G-Y : GREEN AND
YELLOW STRIPE
117 : SECTIONAL AREA
OF l.Omm’ MIN.
SCHEMATIC
NOTE: CONDITION
OF OVEN
1. DOOR CLOSED
2. CONVECTION PAD
TOUCHED
3. DESIRED TEMP. PAD
TOUCHED
4. START PAD TOUCHED
FAN MOTOR
LOWER
LATCH
SWITCH
I
B
CON”ECTlON%ATER
I
UPPER
LATCH
SWITCH
NC
4
I
POWER TRANSFORMER
CAPACITOR
1
RECTIFIER
j !
L
i
1.13/i
AC2200V
HIGH VOLTAGE
RECTIFIER
MAGNETRON
4
Figure O-3. Oven Schematic-Convection Cooking Condition
8
DESCRIPTION AND FUNCTION OF COMPONENTS
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
CPU unit causes the heater relay to operate, thus the
current to the convection heater is turned ON/OFF.
OVEN THERMAL CUT-OUT
The oven thermal cut-out located on the bottom side
of the thermal protection plate is designed to prevent
damage to the convection heater unit if an overheated
condition develops in the tube due to cooling fan failure, obstructed air ducts, dirty or blocked air intake, etc.
Under normal operation, the oven thermal cut-out remains closed. However, when abnormally high temperatures are reached within the heater unit, the oven
thermal cut-out will open, causing the oven to shut
down.
When the oven has cooled temperature, the oven
thermal cut-out closes.
MONITOR SWITCH
The monitor switch is mounted on the upper latch
hook. It is activated (the contacts opened) by the upper latch head when the door is closed. The switch is
intended to render the oven inoperative by means of
blowning the fuse when the contacts of the common
and normal open contacts of upper latch switch fail to
open when the door is opened.
R -8580
CAUTION:BEFORE REPLACING A BLOWN FUSE
TEST THE UPPER LATCH SWITCH AND
MONITOR
SWITCH
FOR
PROPER
OPERATION.(REFER TO CHAPTER “TEST
PROCEDURE”).
AFTER REPLACING FUSE ALSO REPLACE
MONITOR SWITCH.
STOP SWITCH
The stop switch is activated by the lower latch head.
When the door is opened while the oven is in cook
cycle, the stop switch contacts open to de-energize the
relay(RY-l,RY-2,RY-3,RY-4,RY-5).
Then the cook cycle is stopped.
UPPER AND LOWER LATCH SWITCHES
The lower latch switch is mounted in the lower latch
hook and the upper latch switch is mounted in the
upper latch hook.
heads on the door.
They are activated by the latch
When the door is opened, the
switches interrupt the’crrcuit to all components except
CPU unit and relay unit and oven lamp. A cook cycle
cannot take place until the door is firmly closed thereby
activating both interlock switches.
P
’ UPPER
A
LATCH
HOOK
Functions:
1.
When the door is opened, the monitor switch contacts close (to the ON condition) due to their being
normally closed. At this time the the common and
normal open contacts of upper latch switch are in
the OFF condition (contacts open) due to their
being normally open contacts switch.
2.
As the door goes to a closed position, the monitor
switch contacts are first opened and then the
common and normal open contacts of upper latch
switch close. (On opening the door, each of these
switches operate inversely.)
3.
If the door is opened during cooking, and the
common and normal open contacts of upper latch
switch fail to open, the monitor fuse blows simultaneously with closing of the monitor switch contacts.
Figure D-l. Upper Latch Switch, Lower Latch
Switch, Monitor Switch and Stop Switch
R-8580
CONVECTION HEATER Microwave Cooking:
The convection heater 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 convection heater.
Damper is in the open position, because a portion of
cooling air is channeled 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 condensation compartment.
CONVECTION COOKING SYSTEM
This oven is designed with a hot air heating system
where food is not directly heated by the convection
heater, but is heated by forced circulation of the hot
Convection Cooking:
Damper is in the closed position, so that no hot air will
be allowed to leak out the oven cavity.
air produced by the convection heater.
The air heated by the convection heater 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 oven cavity left side wall.
Without leaving the oven, this hot air is reheated by the
convection heater, 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 convection heater is
de-energized. When the temperature inside the oven
cavity drops below the selected temperature, the convection heater 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 convection
heater is deenergzed and the convection fan stops op-
erating and the oven shutts off.
Upon completion of the cooking time, the audible sig-
nal 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 tem-
perature is above 118 OC., the circuit to RY5 will be
maintained (by the thermistor circuit) to continue operation of the cooling fan motor until the temperature
drops below 118 OC., at which time the relay will be
de-energized, turning off the fan motor. Relay RY3 will
however, open as soon as the convection cycle has
ended, turning off the convection fan motor.This will
now cool and allow the damper door to open.
DAMPER OPEN-CLOSE MECHANISM
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
Damper Operation
I, When power supply cord is plugged in:
l-l.
When power supply cord is plugged in, a sig-
nal is sensed in the control unit, and operates
shut-off relay (RY6).
Contacts of shut-off relay (RY6) close, the
1-2.
damper motor is energized, opening the
damper door.
When the damper is moved to the open posi-
1-3.
tion by the damper cam dampe switch is
closed (ON position).
The signal of damper switch is re-sensed in
1-4.
the control unit and shut-off relay (RY6) is
turned off.
The 240 volts A.C. to the damper motor is
1-5.
stopped and the motor turns off.
2. When oven is microwave cooking:
Damper is in the open position.
3. When oven is convection cooking:
3-l.
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 (RY6)
is de-energized.
The damper is held in the closed position
3-3.
during the convection cooking operation.
3-4.
At the end of the convection cooking, shut-off
relay (RY6) is energized, and the damper is
returned to the open position.
NOTE: If the damper door is not in the proper position,
closed durin convection or open durning
microwave, the control unit will stop oven operation after 1 minute.
Cooking Mode Operation of Damper
Microwave cooking OPEN
Convection cooking CLOSE
Sensor cooking OPEN
Automatic mix cooking CLOSE
Grill cooking
Slow cooking CLOSE
is selected by the CPU unit.
CLOSE
10
SERVICING
TROUBLESHOOTING GUIDE
When troubleshooting the microwave oven, it is
helpfull to follow the Sequence of Operation in per-
forming 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.
PROBLEM
POSSIBLE CAUSE
OFF CONDJTION
Home fuse blows when power
cord is plugged into wall recepta-
cle.
Fuse blows when power cord is
plugged into wall receptacle.
88:88 do not appear in display No power at outlet.
when power cord is first plugged
into wall outlet.
Display does not operate properly
when STOP/CLEAR
touched. (B
and time of day should appear in
display.)
Oven lamp does not light with No power in home.
door opened.
uzzer should sound
key is
Shorted wire in power cord or wire harness.
Shorted wire in power cord or wire harness.
Defective monitor switch.
Blown fuse.
Blown magnetron temp. fuse.
Defective thermal cut-out.
Open wire in power cord, wiring harness,
or wrrrng between control panel assembly
units.
Defective CPU unit.
Defective relay unit.
Defective key unit.
Defective CPU unit.
Defective relay unit.
Defective stop switch.
, Open wire in power cord or wire harness. , Replace same or repair wir- 1
Defective oven lamp.
Defective upper latch switch.
Blow fuse.
Defective thermal cut-out.
Defective magnetron temp. fuse.
Open or loose wire connection to the Check wiring.
above components.
IMPORTANT: lf the oven becomes inoperative be-
cause of a blown fuse in the monitor
switch and upper latch switch circuit,
check the monitor switch and upper
latch switch before replacing the fuse.
If the fuse is replaced, the monitor
switch should be replaced at same
time.
-*
TEST PROCEDURE OR
CORRECTION
Replace cord or check wiring.
Replace power cord or check
and repair harness.
Procedure F.
Check home fuse.
Procedure G.
Procedure H.
Procedure I.
Replace or repair wiring.
Procedure 0.
Procedure N.
Procedure P.
Procedure 0.
Procedure N.
Procedure E.
Check wall outlet.
rng.
Replace.
Procedure E.
Procedure G.
Procedure I.
Procedure H.
(RD8’ll OZU)
11
R -8580
PROBLEM POSSIBLE CAUSE
COOKING CONDITION
Oven lamp does not light in cook
cycle.
(Does light when door is opened) Defective CPU unit.
Oven lamp does not light at all.
Oven lamp lights, but turntable
motor does not operate.
Turntable motor operates normally Defective cooling fan motor.
but cooling fan motor does not
operate
MICROWAVE
Oven does not go into a cook cycle when START pad is touched.
Oven seems to be operating but Defective magnetron.
little or no heat is produced in
oven
load.( Food
incompletely Defective power transformer.
cooked or not cooked at all at end
of cook cycle.)
Oven goes into a cook cycle but
extremely
uneven
heating is
produced in oven load(food).
Oven does not cook properly Defective CPU unit.
when programed for MEDIUM Defective key unit.
etc. cooking powers.
(Operates properly on HIGH)
Oven does not cook properly
when programed in EASY DE-
FROST cooking mode.
Defective shut-off relay (RY2) on relay Procedure N.
unit.
Burned out bulb. Replace
Open wiring of oven lamp.
Open or loose wiring to turntable motor. Check and repair wiring
Defective turntable motor.
Defective shut-off relay (RY5) on relay Procedure N.
unit.
Open or loose wiring to fan motor
Upper latch switch and/or lower latch Procedure E.
switch defective or out adjustment.
Defective cook relay (RYI ) on relay unit.
Defective CPU unit.
Defective key unit.
Open or loose wiring to above components.
Defective cook relay (RYI ) on relay unit.
Defective high voltage rectifier.
Defective high voltage capacitor.
Defective CPU unit.
Open or loose wiring to above compo-
nents.
Turntable motor does not operate.
Open or loose wiring to above compo-
I nents.
Defective EASY DEFROST function.
TEST PROCEDURE OR
CORRECTION
Procedure 0.
Check and repair wiring
Replace
Replace.
Check and repair wiring
Procedure N.
Procedure 0.
Procedure P.
Check and repair wiring
Procedure A.
Procedure N.
Procedure B.
Procedure C.
Procedure 0.
Procedure 0.
Check and repair wiring
Replace turntable motor or
check and repair wiring.
Procedure 0.
Procedure P.
Check and repair wiring
Refer to EASY DEFROST
section in operation manual
and check CPU unit.
12
R -8580
PROBLEM
CONVECTION
CONV indicator light but oven
r
does not go into a cook cycle
when START pad is touched.
CONV indicator lights, but heating
element does not heat.
Temperature in the oven cavity is
lower or higher than preset.
Lower than preset temperature.
Cooling fan motor, turntable mo-
tor and oven lamp run
intermitantly or all the time.
Convection cycle runs 3 minutes
then shuts down.
POSSIBLE CAUSE
Defective heater relay(RY4) on relay unit. Procedure N.
Defective key unit.
Defective thermistor. procedure K.
Open wiring in circuit to above components.
Defective convection heater. Procedure J.
Defective heater relay(RY4) on relay unit.
Defective CPU unit.
Open or loose wire connection to the Check and repair wiring.
above components.
Defective convection heater.
Defective CPU unit.
Defective convection motor.
Defective thermistor.
Defective cooling fan motor.
Defective dumper motor.
Defective drive mechanism of convection Check.
fan.
Low power supply voltage.
Thermistor shorted.
Thermistor open.
TEST PROCEDURE OR
CORRECTION
Procedure P.
Check and repair wiring.
Procedure N.
Procedure 0.
Procedure J.
Procedure 0.
Replace motor.
Procedure K.
Replace fan motor.
Procedure L.
Check voltage.
Procedure K.
Procedure K.
SENSOR
Oven is in the sensor cooking AH sensor open and/or short.
condition but AH sensor does not
end stage 1 or does not stop
cooking cycle or the oven stops above components.
soon.
Defective CPU unit.
0
pen or loose wire connection to the Check and repair wiring.
AH sensor assembly and/or steam duct Check and repair them.
are not re-installed correctry.
Procedure 0.
Procedure 0.
13
R-8580
PROCEDURE
LETTER
TEST PROCEDURES
COMPONENT TEST
MAGNETRON ASSEMBLY TEST
DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING.
To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity
check across the magnetron filament leads should indicate less than 1 ohm.
To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament
leads and chassis ground. This test should indicate an infinite resistance. If there is little or no
’ resistance, the magnetron is grounded and must be replaced.
Power output of the magnetron can be measured by performing a water temperature rise test.
This test should only be used if above rests do not indicate a faulty magnetron and there is no
defect in the following components or wiring: high voltage rectifier, rectifier, high voltage
capacitor, and power transformer.
MICROWAVE OUTPUT POWER
Microwave output power from the magnetron can be measured by way of substitution, i.e. it can
be measured by using water load how much it can be absorbed by the water load. To measure
the microwave output power in the microwave oven, the relation of calorie and watt is used.
When P(W) heating works for t(second), approximately P x t/4.2 calorie is generated. On the
other hand, if the temperature of the water with V(ml) rises AT ( “C) during this microwave
heating period, the calorie of the water is V x AT.
The formular is as follows;
Pxt/4.2=Vx AT
P(W)=4.2xVx AT/t
Our condition for the water load is as follows:
Water load . . .
2000 ml, Heating time . ..I 20 seconds
P=7Ox AT
Measuring method;
1. Put the water load of two (2) litres on the center of the oven shelf. The water load should
be arranged in two (2) Pyrex beakers, the size of which is one (1) litre, and be placed at right
and left, side by side, on the oven shelf.
2. Measure the temperature of water before heating and also after heating during 120 seconds
by microwave, and calculate the temperature rise. The temperature rise should be the average
of temperature differences measured in each beaker.
3. The output power should be calculated as follows.
In case the measuring result is not satis-
factory, execute the measurement several times and judge the result from the synthetic point
of view. Microwave output power should be within + 15% of the nominal one.
Calculation of output power;
Microwave output power
. ..P(W)=7Ox AT(%)
AT = ( ATL + ATR) / 2 : average temperature rise
ATL = (TL2 - TLI),
ATR = (TR2 - TRI)
TL2 : water temperature after heating in left beaker
TLI : water temperature before heating in left beaker
TR2 : water temperature after heating in right beaker
TRI : water temperature before heating in right beaker
Measuring condition;
As the microwave output is affected by several conditions, the measurement should be made
carefully with following attentions.
1. Initial temperature of salt water should be 10 + 1 “C. Well and quickly stir the water and the
temperature measurement should be done immediately after heating.
2. The graduation of thermometer should be scaled by 0.1 “C at minimum and an accurate mer-
cury thermometer is recommended.
14
TEST PROCEDURES (CONT’D)
PROCEDURE
LETTER
COMPONENT TEST
3. Water container should be one (1) litre beaker made of Pyrex glass and its diameter approximately 12 cm.
4. Room temperature should be around 20 “C.
5. Power supply voltage should be specification voltage.
POWER TRANSFORMER TEST
DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING.
Disconnect the primary input terminals and measure the resistance of the transformer with an
ohmmeter. Check for continuity of the coils with an ohmmeter. On the R x 1 scale, the resistance
of the primary coil should be approx. 1.6 ohm and the resistance of the high voltage coil should
be approximately 74 ohms; the resistance of the filament coil should be less than 1 ohm.
(HIGH VOLTAGES ARE PRESENT TO HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO
MEASURE THE FILAMENT AND HIGH VOLTAGE.)
C HIGH VOLTAGE RECTIFIER AND RECTIFIER TEST
R-8680
E
D
DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING.
HIGH VOLTAGE RECTIFIER TEST
Isolate the high voltage rectifier from the circuit. Using the highest ohm scale of the meter read
the resistance across the terminals and observe, reverse the leads to the high voltage rectifier
terminals and observe meter reading.
If a short is indicated in both directions, or if an infinite
resistance is read in both directions, the high voltage rectifier is probably defective and should
be replaced.
RECTIFIER TEST
Isolate the rectifier from the circuit. Using the highest ohm scale of the meter, read the resistance
across the terminals, reverse the leads to the rectifier terminals and observe meter reading.
If an
infinite resistance is read in both directions, the rectifier is good.
If a short is indicated in either direction, the one is probably defective and should be replaced.
HIGH VOLTAGE CAPACITOR TEST
DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPO-
NENTS OR WIRING.
If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input
leads and check for short or open, between the terminals using an ohmmeter.
Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate
continuity for a short time and should indicate approximately IOM R once the capacitor is
charged.
If the above is not the case, check the capacitoi’with an ohmmeter to see if it is shorted
between the terminals. If it is shorted, replace the capacitor.
(RD82603U)
SWITCH TEST
Isolate the switch and check the contacts by using an ohmmeter using the following table.
If improper operation is indicated, make the necessary switch adjustment or replacement.
Table: Switch Connection
Connection
Operation
Plunger released
Plunger pushed
Common Terminal-Normally Open Terminal
(COM)
Open circuit
Closed circuit
(NO)
Common Terminal-Normally Close Terminal
(COW
Close circuit
Open circuit
(NC)
(RD82701U)
15
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