Touch Control Panel - Sharp R-380A Service Manual

R-380A
PROCEDURE
LETTER
If the above is not the case, the control unit is probably defective.
If the above is proper, the AH sensor is probably defective.
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 - P27.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P74 - P77
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.
1) ACL
This circuit generates a signal which resets the LSI to
the initial state when power is supplied.
2) Indicator Circuit
This circuit consists of 25 segments and 4 common
electrodes using a Liquid Crystal Display.
3) Power Source Circuit
This circuit generates voltages necessary in the control
unit from the AC line voltage.
TEST PROCEDURES
R1,R2 : 22Ω ± 1% 1/2W
To connector (F)
on Control Unit.
1
F-1
2
F-2
3
F-3
CONNECTOR
Sensor Dummy Resistor Circuit
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
16
COMPONENT TEST
R3 : 4.3kΩ ± 5% 1/4W
R4 : 1MΩ ± 5% 1/4W
R1
R3 R4
R2
In addition, the synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.
Symbol Voltage
VC
4) Relay Circuit
A circuit to drive the magnetron, fan motor, turntable
motor and light the oven lamp.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (key touch sound and completion
sound).
6) 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.
7) Door Sensing Switch
A switch to "tell" the LSI if the door is open or closed.
8) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LD1 - LD5).
9) Absolute Humidity Sensor Circuit
This circuit detects moisture of the cooking food to
allow its automatic cooking.
Plunger
NC
NO
COM
COM NO
NC
Application
-5.3V LSI(IC1)