Sharp R-743 (serv.man3) Service Manual ▷ View online
8
743M -
TOUCH CONTROL ASSEMBLY/DESCRIPTION OF LSI
LSI(IZA918DR)
The I/O signal of the LSI(IZA918DR) are detailed in the following table.
Pin No.
Signal
I/O
Description
1-7
SEG13 -
OUT
Segment data signal.
SEG19
Connected to LCD.
The relation between signals are as follows:
LSI signal (Pin No.)
The relation between signals are as follows:
LSI signal (Pin No.)
LCD
LSI signal (Pin No.) LCD
SEG 13 (1) ..................................... S7
SEG 19 (7) .................................. S1
SEG 14 (2) ..................................... S6
SEG 8 (59) ................................ S12
SEG 15 (3) ..................................... S5
SEG 9 (60) ................................ S11
SEG 16 (4) ..................................... S4
SEG 10 (61) .............................. S10
SEG 17 (5) ..................................... S3
SEG 11 (62) ................................ S9
SEG 18 (6) ..................................... S2
SEG 12 (63) ................................ S8
8
NC
Not connection terminal.
9
NC
Connected to COM2 (LSI Pin No, 49).
10
NC
Connected to COM1 (LSI Pin No, 48).
11
NC
Connected to COM0 (LSI Pin No, 47).
12-13
NC
No connection terminal.
14-16
VC1-VC3
IN/OUT
Terminal not used.
17
XRESET
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.
set "L" level the moment power is supplied, at this time the LSI is reset. Thereafter
set at "H" level.
18
XTEST
IN
Connected to GND.
19
VSS
IN
Power source voltage: -5V.
Power source voltage is applied to drive the LSI.
20
OSC1
IN
Internal clock oscillation frequency setting input.
The internal clock frequency is set by inserting the ceramic filter oscillation circuit with
respect to OSC2 terminal.
respect to OSC2 terminal.
21
OSC2
OUT
Internal clock oscillation frequency control output.
Output to control oscillation input of OSC1.
22
VD1
IN
Power source voltage input terminal.
Power source voltage is applied to drive the oscillation circuit which makes the clock
signal in the LSI.
signal in the LSI.
23
VDD
IN
Power source voltage: 0V.
Power source voltage is applied to drive the LSI.
24
AVDD
IN
Power source voltage input terminal.
Power source voltage is applied to drive the A/D converter in the LSI. Connected to
GND.
GND.
25
AVREF
IN
Reference voltage input terminal.
A reference voltage is applied to drive the A/D converter in the LSI. Connected to
GND.
GND.
26
AVSS
IN
Power source voltage input terminal.
Power source voltage is applied to drive the A/D converter in the LSI. Connected to
VC. (-5V)
VC. (-5V)
27-28
NC
No connection terminal. (Connected to VC (-5V))
29-32
R40-R43
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.
Model in operation is applied to set up its function.
33
NC
No connection terminal.
9
743M -
TOUCH CONTROL ASSEMBLY/ DESCRIPTION OF LSI
Pin No.
Signal
I/O
Description
20.0 msec
H : 0V
L : -5V
A
B
0.1 sec.
2 sec.
H : 0V
L: -5V
H : 0V
L: -5V
(Grill or dual)
ON
OFF
During
cooking
L : -5V
0V
H :
(Grill or dual)
ON
OFF
During
cooking
L : -5V
0V
H :
34
BZ
OUT
Signal to sound buzzer (2.0 kHz).
A: key touch sound.
B: Completion sound.
35
R00
OUT
Terminal not used.
36
R01
OUT
Grill heating element driving signal.
To turn on and off the grill heating element
relay (RY2). "L" level during grill cooking
or dual cooking; "H" level otherwise.
relay (RY2). "L" level during grill cooking
or dual cooking; "H" level otherwise.
37
R02
OUT
Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay
(RY3). In 100% POWER op-
eration, the signals hold "L"
level during microwave cooking
and "H" level while not cooking.
In other cooking modes (70%,
50%, 30%, 10%) the signal turns
to "H" level and "L" level in
repetition according to the power
level.
(RY3). In 100% POWER op-
eration, the signals hold "L"
level during microwave cooking
and "H" level while not cooking.
In other cooking modes (70%,
50%, 30%, 10%) the signal turns
to "H" level and "L" level in
repetition according to the power
level.
38
R03
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.
39
P20
IN
Signal coming from tact switch.
When either of tact switches SW64-SW66 is touched, a corresponding signal out
of SEG1, SEG2 and SEG3 will be input into P20. When no tact switch is touched,
the signal is held at "H" level.
of SEG1, SEG2 and SEG3 will be input into P20. When no tact switch is touched,
the signal is held at "H" level.
40-41
P21-P22
OUT
Terminal not used.
42
P23
IN
Signal coming from tact switch.
When either of tact switches SW60-SW62 is touched, a corresponding signal out
of SEG0, SEG1, SEG2 and SEG3 will be input into P23. When no tact switch is
touched, the signal is held at "H" level.
of SEG0, SEG1, SEG2 and SEG3 will be input into P23. When no tact switch is
touched, the signal is held at "H" level.
43
INT0
IN
Signal synchronized with commercial power source frequency.
This is the basic timing for time processing
of LSI.
of LSI.
44
INT1
IN
Connected to VC. (-5V)
45
K02
IN
Connected to VC. (-5V)
46
K03
IN
To input signal which communicates the door open/close information to LSI.
Door open "L" level signal (-5V). Door close "H" level (0V)
47
COM0
OUT
Common data signal: COM0.
Connected to LCD. (C1)
48
COM1
OUT
Common data signal: COM1.
Connected to LCD. (C2)
49
COM2
OUT
Common data signal: COM2.
Connected to LCD. (C3)
50
COM3
OUT
Terminal not used.
ON/OFF time ratio in Mi-
cro cooking
(a. 32second time base)
cro cooking
(a. 32second time base)
ON/OFF time ratio in Mi-
cro cooking
(a. 48second time base)
cro cooking
(a. 48second time base)
MICRO
ON
OFF
COOK
100%
100%
32sec.
0sec.
70%
24sec.
8sec.
50%
18sec.
14sec.
30%
12sec.
20sec.
10%
6sec.
26sec.
MICRO
ON
OFF
COOK
100%
100%
48sec.
0sec.
70%
36sec.
12sec.
50%
26sec.
22sec.
30%
16sec.
32sec.
10%
8sec.
40sec.
10
743M -
51
SEG0
OUT
Tact switch strobe signal.
Signal applied to tact switch section. A pulse signal is input to P23 terminal while the
tact switch SW60 is touched.
tact switch SW60 is touched.
52
SEG1
OUT
Tact switch strobe signal.
Signal applied to tact switch section. A pulse signal is input to P23 terminal while the
tact switch SW61 is touched. A pulse signal is input to P20 terminal while the tact
switch SW64 is touched.
tact switch SW61 is touched. A pulse signal is input to P20 terminal while the tact
switch SW64 is touched.
TOUCH CONTROL ASSEMBLY/ DESCRIPTION OF LSI
Pin No.
Signal
I/O
Description
53
SEG2
OUT
Tact switch strobe signal.
Signal applied to tact switch section. A pulse signal is input to P23 terminal while the
tact switch SW63 is touched. A pulse signal is input to P20 terminal while the tact
switch SW65 is touched.
tact switch SW63 is touched. A pulse signal is input to P20 terminal while the tact
switch SW65 is touched.
54
SEG3
OUT
Tact switch strobe signal.
Signal applied to tact switch section. A pulse signal is input to P23 terminal while the
tact switch SW62 is touched. A pulse signal is input to P20 terminal while the tact
switch SW66 is touched.
tact switch SW62 is touched. A pulse signal is input to P20 terminal while the tact
switch SW66 is touched.
55-58
SEG4-
OUT
Terminal not used.
SEG7
59-63
SEG8-
OUT
Segment data signal.
SEG12
Signal is similar to SEG13. Connected to LCD.
64
NC
No connection terminal.
WARNING:
Before carrying out any work carry out 3D checks
1)
D
isconnect the supply.
2)
D
oor opened, and wedged open.
3)
D
ischarge high voltage capacitor.
WIRING / RE-WIRING
RE-WIRING
Ensure the following:
1.
Wires must not touch:
a)
High voltage parts.
(Magnetron, high voltage transformer, high voltage capacitor and high voltage rectifier assembly)
(Magnetron, high voltage transformer, high voltage capacitor and high voltage rectifier assembly)
b)
Parts that become hot.
(Heating elements, oven lamp, oven cavity magnetron and high voltage transformer)
(Heating elements, oven lamp, oven cavity magnetron and high voltage transformer)
c)
Sharp edges.
(Bottom plates, oven cavity, waveguide flange, chassis support and other metallic parts)
(Bottom plates, oven cavity, waveguide flange, chassis support and other metallic parts)
d)
Movable parts.
(Fan blade, any motor, switch, switch lever and open button)
(Fan blade, any motor, switch, switch lever and open button)
2.
Positive lock connectors are fitted correctly. Ensure the locking pin is located correctly.
3.
Wires are connected correctly as per pictorial diagram.
4.
No wire leads are trapped by the outer wrap.
11
743M -
TOUCH CONTROL ASSEMBLY
1. Precautions for Handling Electronic Components
This unit uses CMOS LSI in the integral part of the circuits.
When handling these parts, the following precautions
should be strictly followed. CMOS LSI have extremely
high impedance at its input and output terminals. For this
reason, it is easily influenced by the surrounding high
voltage power source, static electricity charge in clothes,
etc., and sometimes it is not fully protected by the built-in
protection circuit.
In order to protect CMOS LSI.
1) When storing and transporting, thoroughly wrap them
When handling these parts, the following precautions
should be strictly followed. CMOS LSI have extremely
high impedance at its input and output terminals. For this
reason, it is easily influenced by the surrounding high
voltage power source, static electricity charge in clothes,
etc., and sometimes it is not fully protected by the built-in
protection circuit.
In order to protect CMOS LSI.
1) When storing and transporting, thoroughly wrap them
in aluminium foil. Also wrap PW boards containing
them in aluminium foil.
them in aluminium foil.
2) When soldering, ground the technician as shown in
the figure and use grounded soldering iron and work
table.
table.
2. Shapes of Electronic Components
3. Servicing of Touch Control Panel
We describe the procedures to permit servicing of the
touch control panel of the microwave oven and the
precautions you must take when doing so.
To perform the servicing, power to the touch control panel
is available either from the power line of the oven itself or
from an external power source.
touch control panel of the microwave oven and the
precautions you must take when doing so.
To perform the servicing, power to the touch control panel
is available either from the power line of the oven itself or
from an external power source.
(1) Servicing the touch control panel with power
supply of the oven :
CAUTION:
THE HIGH VOLTAGE TRANSFORMER OF THE
MICROWAVE OVEN IS STILL LIVE DURING SERV-
ICING AND PRESENTS A HAZARD .
THE HIGH VOLTAGE TRANSFORMER OF THE
MICROWAVE OVEN IS STILL LIVE DURING SERV-
ICING AND PRESENTS A HAZARD .
Therefore, when checking the performance of the
touch control panel, put the outer cabinet on the oven
to avoid touching the high voltage transformer, or
unplug the primary terminal (connector) of the high
voltage transformer to turn it off; the end of such
connector must be insulated with an insulating tape.
After servicing, be sure to replace the leads to their
original locations.
touch control panel, put the outer cabinet on the oven
to avoid touching the high voltage transformer, or
unplug the primary terminal (connector) of the high
voltage transformer to turn it off; the end of such
connector must be insulated with an insulating tape.
After servicing, be sure to replace the leads to their
original locations.
A.
On some models, the power supply cord between
the touch control panel and the oven itself is so
short that the two can't be separated.
short that the two can't be separated.
For those models, check and repair all the controls
(sensor-related ones included) of the touch control
panel while keeping it connected to the oven.
(sensor-related ones included) of the touch control
panel while keeping it connected to the oven.
SERVICING
B.
On some models, the power supply cord between
the touch control panel and the oven proper is so
long enough that they may be separated from each
other. For those models, therefore, it is possible to
check and repair the controls of the touch control
panel while keeping it apart from the oven proper;
in this case you must short both ends of the door
sensing switch (on PWB) of the touch control panel
with a jumper, which brings about an operational
state that is equivalent to the oven door being
closed. As for the sensor-related controls of the
touch control panel, checking them is possible if
the dummy resistor(s) with resistance equal to that
of the controls are used.
long enough that they may be separated from each
other. For those models, therefore, it is possible to
check and repair the controls of the touch control
panel while keeping it apart from the oven proper;
in this case you must short both ends of the door
sensing switch (on PWB) of the touch control panel
with a jumper, which brings about an operational
state that is equivalent to the oven door being
closed. As for the sensor-related controls of the
touch control panel, checking them is possible if
the dummy resistor(s) with resistance equal to that
of the controls are used.
(2) Servicing the touch control panel with power
supply from an external power source:
Disconnect the touch control panel completely from
the oven proper, and short both ends of the door
sensing switch (on PWB) of the touch control panel,
which brings about an operational state that is
equivalent to the oven door being closed. Connect an
external power source to the power input terminal of
the touch control panel, then it is possible to check and
repair the controls of the touch control panel; it is also
possible to check the sensor-related controls of the
touch control panel by using the dummy resistor(s).
the oven proper, and short both ends of the door
sensing switch (on PWB) of the touch control panel,
which brings about an operational state that is
equivalent to the oven door being closed. Connect an
external power source to the power input terminal of
the touch control panel, then it is possible to check and
repair the controls of the touch control panel; it is also
possible to check the sensor-related controls of the
touch control panel by using the dummy resistor(s).
4. Servicing Tools
Tools required to service the touch control panel assembly.
1) Soldering iron: 30W
1) Soldering iron: 30W
(It is recommended to use a soldering iron with a
grounding terminal.)
grounding terminal.)
2) Oscilloscope: Single beam, frequency range: DC -
10MHz type or more advanced model.
3) Others: Hand tools
5. Other Precautions
1) Before turning on the power source of the control unit,
remove the aluminium foil applied for preventing static
electricity.
electricity.
2) Connect the connector of the key unit to the control unit
being sure that the lead wires are not twisted.
3) After aluminium foil is removed, be careful that abnormal
voltage due to static electricity etc. is not applied to the
input or output terminals.
input or output terminals.
4) Attach connectors, electrolytic capacitors, etc. to PWB,
making sure that all connections are tight.
5) Be sure to use specified components where high
precision is required.
approx. 1M ohm
Transistor
2SB1238
2SB1238
Transistor
DTA123ES
DTA143ES
DTB143ES
DTD143ES
DTA123ES
DTA143ES
DTB143ES
DTD143ES
E
C B
E
C
B
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