R-761M - Sharp Home Appliance Service Manual (repair manual). Page 9

9

761M -

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 R20, R21, R22,
R23, R60, R61, R62 and

R63.

When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through R03, R11,
R12, R13 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, absolute humidity sensor 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 control
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

-5.3V

LSI(IC1)

A circuit to drive the magnetron, grill heater, fan
motor, 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 - LD5).

This circuit detects moisture of the cooking food to
allow its automatic cooking.