Sharp R-24STM (serv.man6) Service Manual ▷ View online
R-24STM - 9
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
If the display fails to clear when the STOP/
CLEAR key is depressed, first verify the lead
wire harness is making good contact, verify that
the stop switch operates properly; that is the
contacts are closed when the door is closed
and open when the door is open. If the stop
switch is good, disconnect the lead wire har-
ness that connects the switch unit to the main
board and make sure the stop switch is closed
(either close the door or short the stop switch
connector). Use the Switch unit matrix indi-
cated on the switch unit circuit and place a
jumper wire between the pins that correspond
to the STOP/CLEAR key making momentary
contact. If the is assembly responds by clearing
with a beep the switch unit is faulty and must be
replaced. If the assembly does not respond,
the main board faulty and must be replaced. If
a specific key does not respond, the above
method may be used (after clearing the display
) to determine if the main board or switch unit is
at fault.
CLEAR key is depressed, first verify the lead
wire harness is making good contact, verify that
the stop switch operates properly; that is the
contacts are closed when the door is closed
and open when the door is open. If the stop
switch is good, disconnect the lead wire har-
ness that connects the switch unit to the main
board and make sure the stop switch is closed
(either close the door or short the stop switch
connector). Use the Switch unit matrix indi-
cated on the switch unit circuit and place a
jumper wire between the pins that correspond
to the STOP/CLEAR key making momentary
contact. If the is assembly responds by clearing
with a beep the switch unit is faulty and must be
replaced. If the assembly does not respond,
the main board faulty and must be replaced. If
a specific key does not respond, the above
method may be used (after clearing the display
) to determine if the main board or switch unit is
at fault.
B
SWITCH UNIT TEST
1
2
3
4
SW2
5
6
SW3
SW4
SW5
SW6
SW7
CN-G
SW1
START / AUTO MINUTE
POWER LEVEL
MEAT JOINT
MINCED MEAT
Express Cook
WHOLE POULTRY
STOP / CLEAR
A
TOUCH CONTROL PANEL ASSEMBLY TEST
Do not touch the electrical parts and the printed wiring board to prevent an electric
CAUTION
CAUTION
shock. Because the control unit is " TRANSLESS CIRCUIT " and all electrical parts
are used at A.C. line voltage.
are used at A.C. line voltage.
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore,
unlike conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter
and ohmmeter.
In this service manual, the touch control panel assembly is divided into two units, Control Unit and
Switch Unit, and troubleshooting by unit replacement is described according to the symptoms
indicated.
1. Switch Unit. Note : Check switch unit lead wire harness connection before replacement.
unlike conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter
and ohmmeter.
In this service manual, the touch control panel assembly is divided into two units, Control Unit and
Switch Unit, and troubleshooting by unit replacement is described according to the symptoms
indicated.
1. Switch Unit. Note : Check switch unit lead wire harness connection before replacement.
The following symptoms indicate a defective switch unit. Replace the switch unit.
a) When touching the keys, a certain key produces no signal at all.
b) When touching a key, two figures or more are displayed.
c) When touching the keys, sometimes a key produces no signal.
a) When touching the keys, a certain key produces no signal at all.
b) When touching a key, two figures or more are displayed.
c) When touching the keys, sometimes a key produces no signal.
2. Control Unit
The following symptoms indicate a defective control unit. Before replacing the control unit
perform the Switch unit test (Procedure M) to determine if control unit is faulty.
perform the Switch unit test (Procedure M) to determine if control unit is faulty.
2-1 In connection with keys.
a) When touching the keys, a certain group of keys do not produce a signal.
b) When touching the keys, no keys produce a signal.
b) When touching the keys, no keys produce a signal.
2-2 In connection with indicators
a) At a certain digit, all or some dots do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light.
d) The corresponding dots of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
b) At a certain digit, brightness is low.
c) Only one indicator does not light.
d) The corresponding dots of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
2-3 Other possible problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
b) Clock does not operate properly.
c) Cooking is not possible.
R-24STM - 10
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
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 touch sound and completion
sound).
audible sounds (tact switch 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.
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 (Stop Switch)
A switch to "tell" the LSI if the door is open or closed.
8) Encoder
The encoder converts the signal generated by LSI into the
pulse signal, and the pulse signal is returned to the LSI.
pulse signal, and the pulse signal is returned to the LSI.
9) 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 units.
(1) Switch Unit
(2) Control Unit
(2) Control Unit
The principal functions of these units and the signals
communicated among them are explained below.
communicated among them are explained below.
Switch Unit
The switch unit is composed of a matrix, signals generated
in the LSI are sent to the switch unit through R60, R61, R62
and R63.
When a switch button is touched, a signal is completed
through the switch unit and passed back to the LSI through
R81 and R83 to perform the function that was requested.
The switch unit is composed of a matrix, signals generated
in the LSI are sent to the switch unit through R60, R61, R62
and R63.
When a switch button is touched, a signal is completed
through the switch unit and passed back to the LSI through
R81 and R83 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, synchroniz-
ing signal circuit and back light circuit.
Control unit consists of LSI, ACL circuit, indicator circuit,
power source circuit, relay circuit, buzzer circuit, synchroniz-
ing 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.
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
This circuit generates voltage necessary in the control unit
from the AC line voltage.
from the AC line voltage.
Symbol
Voltage
Application
VC
+5V
LSI(IC1)
R-24STM - 11
LSI(IXA087DR)
The I/O signal of the LSI(IXA087DR) are detailed in the following table.
The I/O signal of the LSI(IXA087DR) are detailed in the following table.
Pin No.
Signal
I/O
Description
HIGH
H : +5V
L : 0V
H : +5V
L : 0V
MEDIUM
HIGH
ON
ON
OFF
OFF
OFF
24 sec.
8 sec.
A
B
0.1 sec.
2 sec.
H : +5V
L: 0V
H : +5V
L: 0V
20.0 msec
During cooking
H : +5V
L : 0V
20.0 msec
H : +5V
L : 0V
1-12
SEG0 -
OUT
Segment data signal.
SEG11
Connected to LCD.
The relation between signals are as follows:
The relation between signals are as follows:
LSI signal (Pin No.)
LCD (Pin No.)
LSI signal (Pin No.) LCD (Pin No.)
SEG 0 (1) ................................ S6
SEG 6 (7) ........................... S12
SEG 1 (2) ................................ S7
SEG 7 (8) ............................. S5
SEG 2 (3) ................................ S8
SEG 8 (9) ............................. S4
SEG 3 (4) ................................ S9
SEG 9 (10) ........................... S3
SEG 4 (5) .............................. S10
SEG 10 (11) ......................... S2
SEG 5 (6) .............................. S11
SEG 11 (12) ......................... S1
13
R60
OUT
Tact switch strobe signal.
Signal applied to tact switch section. A pulse signal is input to R83 terminal while
the tact switch SW1 is touched.
Signal applied to tact switch section. A pulse signal is input to R83 terminal while
the tact switch SW1 is touched.
14
R61
OUT
Tact switch strobe signal.
Signal applied to tact switch section. A pulse signal is input to R81or R83 terminal
while the tact switch SW2 or SW5 is touched.
Signal applied to tact switch section. A pulse signal is input to R81or R83 terminal
while the tact switch SW2 or SW5 is touched.
15
R62
OUT
Tact switch strobe signal.
Signal applied to tact switch section. A pulse signal is input to R81 or R83 terminal
while the tact switch SW3 or SW6 is touched.
Signal applied to tact switch section. A pulse signal is input to R81 or R83 terminal
while the tact switch SW3 or SW6 is touched.
16
R63
OUT
Tact switch strobe signal.
Signal applied to tact switch section. A pulse signal is input to R81 or R83 terminal
while the tact switch SW4 or SW7 is touched.
Signal applied to tact switch section. A pulse signal is input to R81 or R83 terminal
while the tact switch SW4 or SW7 is touched.
17
AIN0
IN
To input signal which communicates the door open/close information to LSI.
Door close "L" level signal (0V). Door open "H" level (+5V)
Door close "L" level signal (0V). Door open "H" level (+5V)
18-20
AIN1-AIN3
IN
Terminal to change functions according to the Model.
By using the A/D converter contained in the LSI, DC voltage in accordance with the
Model in operation is applied to set up its function.
By using the A/D converter contained in the LSI, DC voltage in accordance with the
Model in operation is applied to set up its function.
21
VSS
IN
Power source voltage: 0V.
VSS voltage of power source circuit input.
VSS voltage of power source circuit input.
22
R70
OUT
Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay
(RY2). The signals holds "L" level
during microwave cooking and "H"
level while not cooking. In other cook-
ing modes (variable cooking) the sig-
nal turns to "H" level and "L" level in
repetition according to the power level.
(RY2). The signals holds "L" level
during microwave cooking and "H"
level while not cooking. In other cook-
ing modes (variable cooking) the sig-
nal turns to "H" level and "L" level in
repetition according to the power level.
23
R71
OUT
Signal to sound buzzer (2.0 kHz).
A: Tact switch touch sound.
B: Completion sound.
24
R72
OUT
Oven lamp, fan motor and turntable motor driving signal.
To turn on and off shut off relay (RY1). The
square waveform voltage is delivered to
the RY1 driving circuit.
square waveform voltage is delivered to
the RY1 driving circuit.
25
R73
IN
Signal coming from encoder.
When the encoder is turned, the contacts of encoder make pulse signals. And
pulse signals are input into R73.
When the encoder is turned, the contacts of encoder make pulse signals. And
pulse signals are input into R73.
26
INT2
IN
Signal synchronized with commercial power source frequency.
This is the basic timing for time processing of LSI.
DESCRIPTION OF LSI
R-24STM - 12
DESCRIPTION OF LSI
LSI(IXA087DR)
The I/O signal of the LSI(IXA087DR) are detailed in the following table.
The I/O signal of the LSI(IXA087DR) are detailed in the following table.
Pin No.
Signal
I/O
Description
27
R81
IN
Signal coming from tact switch.
When either of tact switches SW5-SW6 is touched, a corresponding signal out of
R60, R61, R62 and R63 will be input into R81. When no tact switch is touched, the
signal is held at "H" level.
When either of tact switches SW5-SW6 is touched, a corresponding signal out of
R60, R61, R62 and R63 will be input into R81. When no tact switch is touched, the
signal is held at "H" level.
28
INT1
IN
Signal coming from encoder.
Signal similar to R73. Pulse signals are input into INT1.
Signal similar to R73. Pulse signals are input into INT1.
29
R83
IN
Signal coming from tact switch.
When either of tact switches SW1-SW4 is touched, a corresponding signal out of
R60, R61, R62 and R63 will be input into R83. When no tact switch is touched, the
signal is held at "H" level.
When either of tact switches SW1-SW4 is touched, a corresponding signal out of
R60, R61, R62 and R63 will be input into R83. When no tact switch is touched, the
signal is held at "H" level.
30-32
R90-R92
OUT
Terminal not used.
33
XIN
IN
Internal clock oscillation frequency setting input.
The internal clock frequency is set by inserting the capacitor and resistor circuit with
respect to XOUT terminal.
The internal clock frequency is set by inserting the capacitor and resistor circuit with
respect to XOUT terminal.
34
XOUT
OUT
Internal clock oscillation frequency control output.
Output to control oscillation input of XIN.
Output to control oscillation input of XIN.
35
RESET
IN
Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is supplied.
Temporarily set "L" level the moment power is supplied, at this time the LSI is reset.
Thereafter set at "H" level.
Signal is input to reset the LSI to the initial state when power is supplied.
Temporarily set "L" level the moment power is supplied, at this time the LSI is reset.
Thereafter set at "H" level.
36
HOLD
IN/OUT
Connected to VDD.
37
VLC
IN
Signal synchronized with commercial power source frequency.
Signal similar to VSS.
Signal similar to VSS.
38
COM1
OUT
Common data signal.
Connected to LCD(C1).
Connected to LCD(C1).
39
COM2
OUT
Common data signal.
Connected to LCD(C2).
Connected to LCD(C2).
40
COM3
OUT
Common data signal.
Connected to LCD (C3).
Connected to LCD (C3).
41
COM4
OUT
Terminal not used.
42
VDD
IN
Power source voltage input terminal.
Connected to VC.
Connected to VC.
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