Touch Control Panel Assembly - Sharp R-980J Service Manual

R-980J
The touch control section consists of the following units
as shown in the touch control panel circuit.
(1) Key Unit
(2) Control 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 generated in
the LSI are sent to the key unit through P10-P17.
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, synchro-
nizing signal circuit, ACL circuit, buzzer circuit, tempera-
ture measurement circuit, absolute humidity sensor circuit
and indicator circuit.
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.

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL
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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