Touch Control Panel - Sharp R-310HK Service Manual

PROCEDURE
LETTER
STEPS
8) Disconnect the power supply cord, and then remove outer case.
9) Open the door and block it open.
10) Discharge high voltage capacitor.
11) Reconnect all leads removed from components during testing.
12) Re-install the outer case (cabinet).
13) Reconnect the power supply cord after the outer case is installed.
14) Run the oven and check all functions.
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 com-
municated 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 P22, P23, P24, P25,
P26, P31, P32 and P33.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P50, P51,
P52 and P53 to perform the function that was requested.
Control Unit
Control unit consists of LSI, reset circuit, indicator circuit,
power source circuit, relay circuit, buzzer circuit, synchro-
nizing signal circuit and back light circuit.
1) Reset Circuit
This circuit generates a signal which resets the LSI to the
initial state when power is supplied.
2) Indicator Circuit
This circuit consists of 14 segments and 3 common
electrodes using a Liquid Crystal Display.
TEST PROCEDURES
OCCURRENCE
The rated AC voltage is not present between
1 the normal open terminal of the relay RY1 and
the normal open terminal of the relay RY2.
The rated AC voltage is present at primary
2
side of low voltage transformer.
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
COMPONENT TEST
CAUSE OR CORRECTION
Check supply voltage and oven power cord.
Low voltage transformer or secondary circuit defective.
Check and replace control unit assembly.
3) 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
VSS -5V
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- LD3).
17
R-310HK
R-310HW
Application
LSI(IC1)