Sharp R-770AM Service Manual ▷ View online
12
770AM -
Pin No.
Signal
I/O
Description
45
P23
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P74 - P77 terminal
while one of G1 line keys on matrix is touched.
Signal applied to touch-key section. A pulse signal is input to P74 - P77 terminal
while one of G1 line keys on matrix is touched.
46-48
P22-P20
IN/OUT
Terminal not used.
49-50
P17-P16
IN/OUT
Terminal not used.
51
SEG39
OUT
Terminal not used.
60
SEG30
61
SEG29
OUT
Segment data signal.
Connected to LCD.
Connected to LCD.
90
SEG 0
The relation between signals are as follows:
LSI signal (Pin No.)
LCD (Pin No.)
LSI signal (Pin No.) LCD (Pin No.)
SEG 0 (90) ................................ 1
SEG15 (75) ........................... 29
SEG 1 (89) ................................ 2
SEG16 (74) ........................... 28
SEG 2 (88) ................................ 3
SEG17 (73) ........................... 27
SEG 3 (87) ................................ 4
SEG18 (72) ........................... 26
SEG 4 (86) ................................ 5
SEG19 (71) ........................... 25
SEG 5 (85) ................................ 6
SEG20 (70) ........................... 24
SEG 6 (84) ................................ 7
SEG21 (69) ........................... 11
SEG 7 (83) ................................ 8
SEG22 (68) ........................... 23
SEG 8 (82) ................................ 9
SEG23 (67) ........................... 22
SEG 9 (81) .............................. 10
SEG24 (66) ........................... 12
SEG10 (80) ............................. 34
SEG25 (65) ........................... 13
SEG11 (79) ............................. 33
SEG26 (64) ........................... 14
SEG12 (78) ............................. 32
SEG27 (63) ........................... 15
SEG13 (77) ............................. 31
SEG28 (62) ........................... 16
SEG14 (76) ............................. 30
SEG29 (61) ........................... 17
91
VCC
IN
Connected to GND.
92
VREF
IN
Connected to GND.
93
AVSS
IN
Connected to VC.
94
COM3
OUT
Common data signal: COM3.
Connected to LCD (Pin No. 21).
Connected to LCD (Pin No. 21).
95
COM2
OUT
Common data signal: COM2.
Connected to LCD (Pin No. 20).
Connected to LCD (Pin No. 20).
96
COM1
OUT
Common data signal: COM1.
Connected to LCD (Pin No. 19).
Connected to LCD (Pin No. 19).
97
COM0
OUT
Common data signal: COM0.
Connected to LCD (Pin No. 18).
Connected to LCD (Pin No. 18).
98-99
VL3-VL2
IN
Power source voltage input terminal.
Standard voltage for LCD.
Standard voltage for LCD.
100
C2
IN
Terminal not used.
TOUCH CONTROL / DESCRIPTION OF LSI
13
770AM -
Transistor
2SB910M
2SB910M
Transistor
2SA933S
KRA101M
KRC243M
2SA933S
KRA101M
KRC243M
1. Precautions for Handling Electronic Components
This unit uses CMOS LSI in the integral part of the
circuits. When handling these parts, the following pre-
cautions 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 electric-
ity 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
circuits. When handling these parts, the following pre-
cautions 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 electric-
ity 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 con-
taining them in aluminium foil.
taining them in aluminium foil.
2) When soldering, ground the technician as shown in
the figure and use grounded soldering iron and
work table.
work table.
approx. 1M ohm
2. Shapes of Electronic Components
E
C
B
E
C B
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
SERVICING AND PRESENTS A HAZARD .
THE HIGH VOLTAGE TRANSFORMER OF THE
MICROWAVE OVEN IS STILL LIVE DURING
SERVICING 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 trans-
former, 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 insulat-
ing 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 trans-
former, 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 insulat-
ing tape. After servicing, be sure to replace the
leads to their original locations.
A. On some models, the power supply cord be-
tween the touch control panel and the oven itself
is so short that the two can't be separated.
is so short that the two can't be separated.
For those models, check and repair all the
controls (sensor-related ones included) of the
controls (sensor-related ones included) of the
touch control panel while keeping it connected
to the oven.
to the oven.
B. On some models, the power supply cord be-
tween 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.
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.
(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 termi-
nal 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).
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 termi-
nal 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 as-
sembly.
1) Soldering iron: 30W
sembly.
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 prevent-
ing static electricity.
ing static 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.
applied to the 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.
SERVICING
TOUCH CONTROL
14
770AM -
If the monitored latch switch, stop switch and monitor
switch do not operate properly due to a mis-adjustment,
the following adjustment should be made.
1. CARRY OUT 3D CHECKS.
2. Loosen the two (2) screws holding the latch hook to
switch do not operate properly due to a mis-adjustment,
the following adjustment should be made.
1. CARRY OUT 3D CHECKS.
2. Loosen the two (2) screws holding the latch hook to
the oven cavity front flange.
3. With the door closed, adjust the latch hook by moving
it back and forward or up and down. In and out play
of the door allowed by the latch hook should be less
than 0.5 mm. The horizontal position of the latch
hook should be placed where the monitor switch has
activated with the door closed. The vertical position
of the latch hook should be placed where the
monitored latch switch and stop switch have activated
with the door closed.
of the door allowed by the latch hook should be less
than 0.5 mm. The horizontal position of the latch
hook should be placed where the monitor switch has
activated with the door closed. The vertical position
of the latch hook should be placed where the
monitored latch switch and stop switch have activated
with the door closed.
4. Secure the screws with washers firmly.
5. Make sure of the monitored latch switch, stop switch
5. Make sure of the monitored latch switch, stop switch
and monitor switch operation. If those switches have
not activated with the door closed, two (2) screw
holding latch hook to oven cavity front flange and
adjust the latch hook position.
not activated with the door closed, two (2) screw
holding latch hook to oven cavity front flange and
adjust the latch hook position.
After adjustment, make sure of following:
1. In and out play of door remains less than 0.5 mm when
latched position. First check latch hook position,
pushing and pulling the door toward the oven face.
The results (play of the door) should be less than
0.5mm.
pushing and pulling the door toward the oven face.
The results (play of the door) should be less than
0.5mm.
MONITORED LATCH SWITCH, STOP SWITCH AND MONITOR SWITCH ADJUSTMENT
2. The contacts (COM-NO) of the monitored latch switch
and stop switch interrupt the circuit before the door
can be opened.
can be opened.
3. The contacts (COM-NC) of the monitor switch close
when the door is opened.
4. Re-install outer case and check for microwave leakage
around the door with an approved microwave survey
meter. (Refer to Microwave Measurement Procedure.)
meter. (Refer to Microwave Measurement Procedure.)
DOOR
LATCH HOOK
MONITOR SWITCH
PRIMARY
LATCH SWITCH
LATCH SWITCH
STOP SWITCH
OPEN LEVER
LATCH
HEADS
HEADS
Figure C-4 Latch Switches Adjustment
MONITORED
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
15
770AM -
right edge of the front door glass into the one (1) tab
of the door frame.
of the door frame.
2. Re-install the glass stopper to the door frame as
follows.
1) Re-install the glass stopper to the door frame so
that the two (2) holes of the glass stopper meet the
two (2) pins of the door frame.
two (2) pins of the door frame.
2) Hold the glass stopper to the door frame with the
two (2) screws.
3. Re-install the latch spring to the latch head. Re-
install the latch spring to the door frame. Re-install
latch head to door frame.
latch head to door frame.
4. Re-install door panel to door frame by fitting eight
(8) tabs of door frame to eight (8) holes of door
panel.
panel.
5. Fit the door panel to the door frame with four (4)
screws.
6. Insert two (2) pins of door panel on two (2) hole of
upper and lower oven hinges.
7. Re-install choke cover to door panel.
Note: After any service to the door;
Make sure that door sensing switch and moni-
tored latch switch are operating properly.
tored latch switch are operating properly.
PIN
PIN
LOWER
OVEN HINGE
OVEN HINGE
UPPER
OVEN HINGE
OVEN HINGE
LOWER
OVEN HINGE
OVEN HINGE
CHOKE COVER
DOOR
PANEL
PANEL
DOOR SUB
ASSEMBLY
ASSEMBLY
Figure C-6. Door Replacement
DOOR REPLACEMENT
REMOVAL
1. CARRY OUT 3D CHECKS.
2. Push the open button and open the door slightly.
3. Insert a putty knife (thickness of about 0.5mm) into
2. Push the open button and open the door slightly.
3. Insert a putty knife (thickness of about 0.5mm) into
the gap between the choke cover and door frame as
shown in Figure C-5 to free engaging parts.
shown in Figure C-5 to free engaging parts.
4. Release choke cover from door panel.
5. Now choke cover is free.
5. Now choke cover is free.
CHOKE COVER
PUTTY KNIFE
DOOR FRAME
Figure C-5. Door Disassembly
6. Release two (2) pins of door panel from two (2) holes
of upper and lower oven hinges by lifting up.
7. Now, door sub assembly is free from oven cavity.
8. Remove the four (4) screws holding the door panel to
8. Remove the four (4) screws holding the door panel to
the door frame.
9. Release door panel from eight (8) tabs of door frame
by sliding door panel downward.
10.Now, door panel is free.
11.Slide latch head upward and remove it from door
11.Slide latch head upward and remove it from door
frame, releasing latch spring from door frame and
latch head.
latch head.
12.Now, latch head and latch spring are free.
13.Remove the two (2) screws holding the glass stopper
13.Remove the two (2) screws holding the glass stopper
to the door frame.
14.Remove the glass stopper from the door frame.
15.Slide the front door glass leftwards and then slide
15.Slide the front door glass leftwards and then slide
upwards to release the tabs holding it.
16.Now, the front door glass is free
RE-INSTALL
1. Re-install the front door glass to the door frame as
1. Re-install the front door glass to the door frame as
follows.
1) Insert the upper edge of the front door glass into the
six (6) tabs of the door frame.
2) Slide the front door glass downwards and insert the
lower edge of the front door glass into the six (6) tabs
of the door frame.
of the door frame.
3) Slide the front door glass rightwards and insert the
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
Click on the first or last page to see other R-770AM service manuals if exist.