R-464 (serv.man7). Complete - Sharp Home Appliance Service Manual (repair manual). Page 15

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OUTLINE OF TOUCH CONTROL PANEL

The touch control section consists of the following units.

(1) Key Unit
(2) Control Unit (The Control Unit consists of Power Unit

and CPU 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 P20, P21, P22,
P23, P24, P25 and P26.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P43, P44,
P45 and P46 to perform the function that was requested.

Control Unit
Control unit consists of LSI, ACL circuit, indicator circuit,
power source circuit, relay circuit, buzzer circuit, synchro-
nizing signal circuit and back light circuit.

This circuit generates a signal which resets the LSI to
the initial state when power is supplied.

This circuit consists of 22 segments and 3 common
electrodes using a Liquid Crystal Display.

This circuit generates voltages necessary in the con-
trol unit from the AC line voltage.
In addition, the synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.

Symbol

Voltage

Application

VC

-5V

LSI(IC1)

A circuit to drive the magnetron, fan motors, turntable
motor and light the oven lamp.

The buzzer is responsive to signals from the LSI to emit
audible sounds (key touch sound and completion
sound).

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.

A switch to “tell” the LSI if the door is open or closed.

A circuit to drive the back light (Light emitting diodes
LD1- LD4).