Read Sharp R-242M Service Manual online
8
R-242M -
TOUCH CONTROL PANEL ASSEMBLY
This circuit generates voltage necessary in the control
unit from the AC line voltage.
unit from the AC line voltage.
Symbol
Voltage
Application
VC
+5V
LSI(IC1)
4) Relay Circuit
To drive the magnetron, fan motor, turntable motor and
light the oven lamp.
light the oven lamp.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (tact switch sound and completion
sound).
audible sounds (tact switch 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.
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
LED1-LED3)
LED1-LED3)
The touch control section consists of the following circuits
as shown in the touch control panel circuit.
as shown in the touch control panel circuit.
The principal functions of these circuits and their related
signals are explained below.
signals are explained below.
Tact Switch
Signals generated in the LSI are sent to the tact switches
through R60, R61, R62 and R63.
When a tact switch is touched, a signal is completed
through the tact switch and passed back to the LSI through
R81 to perform the function that was requested.
through R60, R61, R62 and R63.
When a tact switch is touched, a signal is completed
through the tact switch and passed back to the LSI through
R81 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 and back light circuit.
power source circuit, relay circuit, buzzer circuit, synchro-
nizing signal circuit and back light circuit.
1) ACL
This circuit generates a signal which resets the LSI to
the initial state when power is supplied.
the initial state when power is supplied.
2) Indicator Circuit
This circuit consists of 4-digits, 12-segments and 3-
common electrodes using a Liquid Crystal Display.
common electrodes using a Liquid Crystal Display.
3) Power Source Circuit
OUTLINE OF TOUCH CONTROL PANEL
PROCEDURE
LETTER
COMPONENT TEST
NOTE: *At the time of making these repairs,
make a visual inspection of the varistor.
Check for burned damage. If any ab-
normal condition is detected, replace
the defective parts.
Check for burned damage. If any ab-
normal condition is detected, replace
the defective parts.
D
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(PWB) IS OPEN
1
5
RY2
(J1)
a
d
c
b
CN-A
RY1
D1
VRS1
D71
ZD71
To protect the electronic circuits, this model is provided with a fine foil pattern added to the input circuit
on the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide
given below for repair.
Problem: POWER ON, indicator does not light up.
on the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide
given below for repair.
Problem: POWER ON, indicator does not light up.
STEPS
OCCURRENCE
CAUSE OR CORRECTION
1
The rated voltage is not applied between Pin
Check supply voltage and oven power cord.
No. 5 of the 3 pin connector (A) and the
common terminal of the relay RY2.
2
Only pattern at "a" is broken.
*Insert jumper wire J1 and solder.
3
Pattern at "a" and "b" are broken.
*Insert the coil RCILF2003YAZZ between "c" and "d".
TEST PROCEDURES
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