R-653. Text - Sharp Home Appliance Service Manual (repair manual). Page 8

8

R-653M -

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.

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, P26 and P27.
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 consists of LSI, ACL circuit, indicator
circuit, power source circuit, relay circuit, buzzer
circuit, synchronizing 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 4-digits, 12-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

-5.2V

LSI(IC1)

A circuit to drive the magnetron, grill heating
element, 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).

OUTLINE OF TOUCH CONTROL PANEL