Touch Control Panel Assembly; Outline Of Touch Control Panel; Keyboard Unit; Control Unit And Power Unit - Sharp KB-3425LS Service Manual

The touch control section consists of the following units.

() Keyboard unit

(2) Control Unit
(3) Power unit
The principal functions of these units and the signals com-
municated among them are explained below.
Keyboard unit
The keyboard unit is composed of a matrix, signals gener-
ated in the LSI are sent to the keyboard unit . When a key
pad is touched, a signal is completed through the keyboard
unit and passed back to the LSI to perform the function that
was requested.

Control Unit and Power Unit

Control unit consists of LSI, IC, reset circuit, indicator circuit,
power source circuit, relay circuit, buzzer circuit, synchro-
nizing signal circuit, keyboard unit circuit, humidity sensor
circuit and back light circuit.
1) IC1 (LSI)
This is a microcomputer, responsible for controlling the
entire control unit.
2) IC2
This is the IC to judge the selected key.
3) IC3
This is the IC to judge the selected key.
4) IC4
This is the IC to judge the selected key.
5) IC5
This is the IC to amplify the signal from the humidity
sensor and the IC to amplify the signal to adust the
contrast of LCD.
6) IC6
This is memory IC.
7) IC7
This is the IC to drive the relays.
8) IC8
This is the IC to drive the relays.
9) Reset Circuit
This circuit generates a signal which resets the LSI (IC)
to the initial state when power is supplied.
10) Indicator Circuit
A circuit to drive the Liquid Crystal Displays (LCD).
) Power Source Circuit
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
VC +5V

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL

Application
LSI(IC)
12) Relay Circuit
A circuit to drive the magnetron, fan motor, stirrer motor,
convection motor, door lock motor, bottom heater, top
heater, convection heater and light the oven lamp.
3) Buzzer Circuit
The buzzer is responsive to signals from the LSI to
emit audible sounds (key touch sound and completion
sound).
4) 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.
15) Door Sensing Switch (Microwave drawer)
A switch to "tell" the LSI if the drawer is open or
closed.
16) Door Switch (Oven)
A switch to "tell" the LSI if the oven door is open or
closed.
17) Door Lock Monitor Switch (Oven)
A switch to "tell" the LSI if the oven door is locked or
not.
18) Door Position Switch Front / Rear
The switch to "tell" the position of the Microwave drawer
door.
19) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LD- LD5).
20) Cook Top Warmer Indicator Circuit
A circuit to drive the indicator (LD0) for Cook Top
Warmer.
21) Transparent electrode (Touch key) on the
LCD
When the  - 6 of the transparent electrodes are
touched, the signal are input into the P96, P-95, P94,
P92, P9 and P90 of the LSI (IC-) to perform the
function that was requested.
22) Humidity Sensor Circuit
This circuit detects moisture of the cooking food to allow
its automatic cooking.
23) 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.
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KB-3425LS/K/W
KB-4425LS/K/W