Sharp Carousel R-350J, Service Manual

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R-350J
13
NOTE: *At the time of making these repairs,
make a visual inspection of the varistor.
Check for burned damage and exam-
ine the transformer with a tester for the
presence of layer short-circuit (check
the primary coil resistance). If any ab-
normal condition is detected, replace
the control unit assembly.
CARRY OUT 4R CHECKS.
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
RY1
VRS1
T1
RY3
(J1)
a
b
c
d
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
The touch control section consists of the following units.
(1) Key Unit
(2) Control Unit (The Control Unit consists of Power Unit and
LSI Unit).
The principal functions of these units and the signals communi-
cated 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 P00-P07.
When a key pad is touched, a signal is completed through the
key unit and passed back to the LSI through P14-P17, ANI6 and
ANI7 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 40 segments and 16 common
electrodes using a Liquid Crystal Display. The Liquid Crystal
Display (LCD) is drived by LCD driver IC3.
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 Application
VC -5V LSI(IC1)
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) 2nd. Interlock Relay Control 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 LD10-
LD15).