Sharp Carousel R-880F Manuale di servizio - Pagina 9

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Sharp Carousel R-880F Manuale di servizio

Selected Temp-

Top Heaters

erature (˚C)

Power (%)

250

230

220

200

180

160

150

130

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-ener-

gized. At the end of the convection cycle, if the cavity

air temperature is above 120˚C, the circuit to (RY5) will

be maintained (by the thermistor circuit) to continue

operation of the cooling fan motor until the temperature

drops below 104˚C, at which time the relay will be de-

energized, turning off the fan motor. Relay (RY1) will

however, open as soon as the convection cycle has

ended, turning off the convection fan motor.

ABSOLUTE HUMIDITY SENSOR (AH SENSOR)

COOKING CONDITION

In case where the AH sensor is used (REHEAT SENSOR

or SENSOR INSTANT ACTION), the foods are cooked in

microwave cooking mode or grill cooking mode without

figuring time, power level or quantity. When the oven

senses enough steam from the food, it relays the informa-

tion to its microprocessor which will calculate the remaining

cooking time and power level needed for best results.

When the food is cooked, water vapour is developed. The

sensor "senses" the vapour 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 ex-

periment with each food category and inputted into the LSI.

An example of how sensor works:

1. Potatoes at room temperature. Vapour is emitted very

slowly.

2. Heat potatoes. Moisture and humidity is emitted rap-

idly. You can smell the aroma as it cooks. ;

AH SENSOR

Bottom Heater

Power (%)

3. Sensor detects moisture and humidity and calculates

cooking time and variable power.

AH SENSOR COOKING SEQUENCE

1. In case the AH sensor cooking condition is started, the

coil of shut-off relays (RY5+RY6) are energized, the

oven lamp and cooling fan motor are turned on, but the

power transformer is not turned on.

NOTE: The oven should not be operated on AH SENSOR

COOKING immediately after plugging in the unit.

Wait t wo minutes before cooking on AH SENSOR

COOKING CONDITION.

2. After about 16 seconds, the cook relay (RY2) is ener-

gized. 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

vapour from the oven cavity and sensor.

(Figure O-2)

NOTE: During this first stage, do not open the door or

touch STOP/CLEAR pad.

There is a menu which the oven operates in grill

cooking mode.

3. When the sensor detects the vapour 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.

NOTE: In case where a small quantity of food is cooked,

the oven will stop without displaying the remaining

cooking time. In case of "Reheat Pie" of Sensor

Instant Action, the relay (RY2) is turned off and

power transformer is turned off. And then the

relays (RY3 + RY4) are energized. The top and

bottom heaters are turned on.

4. When the timer reaches zero, an audible signal sounds.

The shut-off relay (RY5+RY6) and cook relay (RY2)

are de-energized and the power transformer, oven

lamp, etc. are turned off.

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 accomplished by the LSI

repeatedly measures 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 700mV grater 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 turntable motor and the oven lamp.

The LSI also stops counting down. 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 meas-

urement 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 700mV the LSI makes the

R-880F(S)