Control Panel Assembly - Sharp R-4A52 Service Manual

R-4A52
A-4E52
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
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 SO-S6.
When a key pad is touched, a signal is completed
through the key unit and passed back to the LSI
through K4-K7 to perform the function that was re-
quested.
Control Unit
Control unit consists of LSI, power source circuit,
synchronizing signal circuit, ACL circuit, buzzer circuit
and indicator circuit.
1)
a
3)
LSI
This LSI controls the key strobe signal, relay driving
signal for oven function and indicator signal.
Power Source Circuit
This circuit generates voltage necessary in the
control unit.
Symbol Voltage Application
VDD -12v LSI (ICY), ACL circuit
VREF
VP
~~i:"V LSI (ICI)
Fluorescent display tube : Grid
VF+
and anode voltage.
3V P-P F$rrenent of fluorescent display
VF- (VF+ to VF- voltage)
Synchronizing Signal Circuit
The power source synchronizing signal is available
in order to compose a basic standard time in the
clock circuit.
It accompanies a very small error because it works
on commercial frequency.
4)
5)
6)
7)
8)
ACL Circuit
A circuit to generate a signal which resets the LSI
to the initial state when power is supplied.
Buzzer Circuit
The buzzer is responsive to signals from the
to emit noticing sounds (key touch sound
completion sound).
LSI
and
Door Sensing Switch
A switch to "tell" the LSI if the door IS open or
closed.
Relay Circuit
To drive the magnetron, fan motor, turntable motor
and light the oven lamp.
Indicator Circuit
Indicator element is a Fluorescent Display.
Basically, a Fluorescent Display is a triode having
I
a cathode, a grid and an anode. Usually, the cath-
ode of a Fluorescent Display is directly heated and
the filament serves as cathode.
The Fluorescent Display has 6-digits, 13-segments
are used for displaying figures.
I
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