Sharp SMD2499FS Service Manual page 10

SMD2499FS
HEATER (BAKE/ROAST/GRILL) COOKING CONDITION
"PREHEATING CONDITION"
Program desired convection temperature by touching the
BAKE/ROAST/GRILL pad and touch "1" key and the
Temperature pad. Program desired cooking time by touching
the Number pads.
(NON-PREHEATING COOKING: touch "2" key and the
temperature pad, and cooking time by touching number
key pads.)
When the START pad is touched, the following operations
occur:
1. The coil of shut-off relays (RY10 and RY14) are energized,
MG cooling fan motor and cooling fan motor are turned
on.Top convection motor is turned on also. But power of
this motor is DC24V. DC motor is not controlled by relay.
2. The coil of relay (RY11/RY12) is energized by the control
unit. The damper is moved to the closed position, closing
the damper switch contacts. The closing of the damper
switch contacts sends a signal to the LSI on the control
unit de-energizing the relay (RY11/RY12) and opening
the circuit to the damper motor.
3. The coil of heater relay (RY1, RY3, RY4 and RY7) 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 top convection thermistor,
opening the circuit to the heating element.
4-2. The oven will continue to function for 20 minutes,
turning the heater on and off, as needed to maintain
the selected preheat temperature. The oven will
shut down completely after 20 minutes.
HEATER (BAKE/ROAST/GRILL) 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.
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, MG cooling fan motor, cooling fan motor
and convection motor are energized.
3. Heater relay (Note1) 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 and convection motor are
de-energized. At the end of the convection cycle, if
the cavity air temperature is above 248°F, the circuit to
RY10/RY14 will be maintained (by the thermistor circuit)
to continue operation of the cooling fan motor until the
temperature drops below 221οF, at which time the relay
will be de-energized, turning off the fan motor. However,
as soon as the convection cycle has ended, turning off
the top convection fan motor.
5. At the end of the convection cook cycle, shut-off relay
(RY11/RY12) is energized turning on the damper motor.
The damper is returned to the open position, opening
the damper switch contacts which send a signal to the
control unit, de-energizing shut-off relay (RY11/RY12).
Note 1
Bake RY1, RY3, RY6
Roast RY1, RY3, RY4, RY7, or RY1, RY3, RY6
Grill RY1, RY3, RY5, RY8
SPEED COOKING CONDITION
Touch the Speed Cook pad first. And then program desired
cooking mode by touching the Number pads.
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 increase
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.
2. Heat potatoes. Moisture and humidity are emitted rapidly.
You can smell the aroma as it cooks.
3. Sensor detects moisture and humidity and calculates
cooking time and variable power.
AH SENSOR
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