Sensor Cooking Condition; Auto Defrost Cooking; Fire Sensing Feature (Microwave Mode) - Wolf SUB-ZERO MC24 Service Manual

MC24

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 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 vapor is developed.
The sensor "senses" the vapor and its resistance increases
gradually. When the resistance reaches the value set ac-
cording 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.
Vapor is emitted very slowly.
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
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.

AUTO DEFROST COOKING

The AUTO DEFROST key is a special function key to de-
frost meats and poultry faster and better. AUTO DEFROST
automatically defrosts roast beef, etc.. When the AUTO
DEFROST is selected and the food weight is entered by
using the AUTO DEFROST pad, the oven will cook accord-
ing 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 dur-
ing 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 volt-
age 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.
AH SENSOR
Operation
Please refer to the timing diagrams below.
1. The thermistor operates within a 32-seconds time
2. The above procedure is repeated. If the difference
3. Once the fire sensor feature has shut the unit down, the
IMPORTANT:
During sensor cooking operation, the fire sensing op-
eration sequence will not begin until the AH sensor has
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.
CONVECTION
THERMISTOR
12
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.
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.
programmed cooking cycle may be resumed by pressing
the "START" pad or the unit may be reset by pressing
the "CLEAR" pad.
0 2 3 24 30 32 (sec.)
6 sec.
MOTOR ON
OFF
3 sec.
ON
OFF
ON
Sensing
Voltage
OFF
Sensing the voltage across temperature measurement circuit.
64 (sec.)