Dacor DCM24B Service Manual page 10

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 CONVECTION
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% micro-
wave 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.
6 SEC.
ON
(MICRO.)
OFF
(CONVEC.)
12 SEC.
ON
(MICRO.)
(CONVEC.)
OFF
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, SENSOR REHEAT or POP-
CORN 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 micro-
processor 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 cooking is started. The time of supplemen-
tary 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.
7
26 SEC.
MICROWAVE POWER
= APPROX. 10%
CONVECTION
TEMPERATURE
LOW MIX
BAKE
20 SEC.
MICROWAVE POWER
OFF
= APPROX. 30%
ON
CONVECTION
TEMPERATURE
32 SEC.
HIGH MIX
ROAST
DCM24B
DCM24R
DCM24S
= 350˚F
=300˚F