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PROCEDURE
LETTER
NOTE: *At the time of these repairs, make a
CARRY OUT 4R CHECKS.
The touch control section consists of the following units as
shown in the touch control panel circuit.
The principal functions of these units and the signals
communicated among them are explained below.
Tact Switch
Signals R60, R61, R62 and R63 generated in the LSI are
sent to the tact switches.
When a tact switch is touched, a signal is completed
through the tact switch and passed back to the LSI through
R53 to perform the function that was requested.
Control Unit
Control unit consists of LSI, power source circuit, relay
circuit, back light circuit, synchronizing signal circuit, ACL
circuit, buzzer circuit and indicator circuit.
1) LSI
This LSI controls the tact switch strobe signal, relay
driving signal for oven function and indicator signal.
2) Power Source Circuit
This circuit generates voltage necessary in the control
unite.
Symbol
Voltage
VC
+5V
3) 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.
TEST PROCEDURES
visual inspection of the varistor for
burning damage and examine the
transformer with tester for the pres-
ence of layer short circuit (check pri-
mary coil resistance). f any abnormal
condition is detected, replace the de-
fective parts.
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
Application
LSI(IC1)
COMPONENT TEST
RY2
OL / FM
/ TTM
5
4) Reset Circuit
A circuit to generate a signals which resets the LSI to
the initial state when power is supplied.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (tact switch touch sound and comple-
tion sound).
6) 2nd. Interlock Relay Control Switch
A switch to "tell" the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, fan motor, antenna motor and
light the oven lamp.
8) Indicator Circuit
This circuit consists of 4-digits, 12-segments and 3-
common electrodes using a Liquid Crystal Display.
9) Encoder
The encoder converts the signal generated by power
source circuit into the pulse signal, and the pulse signal
is returned to the LSI.
10) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LED1-LED4)
15
R-15AM
D20
d
VRS1
a
b
AC
c
1
CN - A
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