Operation
2-7
2. Step 1 is repeated. If the difference between the first
voltage measured (in step 1) and 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.
3. Once the fire sensor feature has shut the unit down,
the programmed cooking cycle may be resumed by
pressing the “START” pad or the unit may be reset by
pressing the “CLEAR” pad.
During sensor cooking operation, the fire sensing
operation 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 sensors’ vapor detection.
Touch Control Panel Assembly
The touch control section consists of the following units.
1. Key Unit
2. Control Unit (Consists of Power Unit and LSI Unit).
The principal functions of these units and the signals
communicated among them are explained below.
Key Unit
The key unit is composed of a matrix, signals P10 - P17
generated in the LSI are sent to the key unit. When a key
pad is touched, a signal is completed through the key unit
and passed back to the LSI through R24 - R27 to perform
the function that was requested.
Control Unit
Control unit consists of LSI, power source circuit,
synchronizing signal circuit, ACL circuit, buzzer circuit,
temperature measurement circuit, absolute humidity
sensor circuit and indicator circuit.
IMPORTANT:
ON
OFF
ON
OFF
ON
OFF
0 2 3 24 30 32 (sec.) 64 (sec.)
3 sec.
S
e
nsing the voltage across temperature measurement circuit.
6 sec.
Sensing
Voltage
Thermistor
Convection
Motor
1. LSI
This LSI controls the temperature measurement
signal, AH sensor signal, key strobe signal, relay
driving signal for oven function and indicator signal.
2. Power Source Circuit
This circuit generates the voltages necessary for the
control unit from the AC line voltage.
3. Synchronizing Signal Circuit
The power source synchronizing signal is available in
order to compose a basic standard time in the clock
circuit. It incorporates a very small error because it
works on commercial frequency.
4. ACL Circuit
A circuit to generate a signals which resetting the LSI
to the initial state when power is applied.
5. Buzzer Circuit
The buzzer is responds to signals from the LSI to
emit noticing sounds (key touch sound and
completion sound).
6. Temperature Measurement Circuit : (OVEN
THERMISTOR) The temperature in the oven cavity is
sensed by the thermistor. The variation of resistance
according to sensed temperature is detected by the
temperature measurement circuit and the result
applied to LSI. The LSI uses this information to
control the relay and display units.
7. Absolute Humidity Sensor Circuit
This circuit detects the humidity of a food which is
being cooked, to control its automatic cooking.
8. Door Sensing Switch
A switch to inform the LSI if the door is open or
closed.
9. Relay Circuit
To drive the magnetron, heating element, fan motor,
convection motor, damper motor, turntable motor and
light the oven lamp.
10. Indicator Circuit
Indicator element is a Fluorescent Display. Basically,
a Fluorescent Display is triode having a cathode, a
grid and an anode. Usually, the cathode of a
Fluorescent Display is directly heated and the
filament serves as cathode. The Fluorescent Display
has 8-digits, 16-segments are used for displaying
figures.
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