Sharp R-752M (serv.man2) Service Manual ▷ View online
9
752M -
Pin No.
Signal
I/O
Description
26
P40
IN
Connected to VC through the pull-down resistor R90.
27
RESET
IN
Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is applied. Temporarily
set "L" level the moment power is applied, at this time the LSI is reset. Thereafter
set at "H" level.
set "L" level the moment power is applied, at this time the LSI is reset. Thereafter
set at "H" level.
28-29
P71-P70
OUT
Terminal not used.
30
XIN
IN
Internal clock oscillation frequency input setting.
The internal clock frequency is set by inserting the ceramic filter oscillation circuit
with respect to XIN terminal.
with respect to XIN terminal.
31
XOUT
OUT
Internal clock oscillation frequency control output.
Output to control oscillation input of XOUT.
32
VSS
IN
Power source voltage: -5.0V.
VC voltage of power source circuit input.
33
P27
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P43, P44, P45 and
P46 terminal while one of G1 line keys on key matrix is touched.
P46 terminal while one of G1 line keys on key matrix is touched.
34
P26
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P43, P44, P45 and
P46 terminal while one of G2 line keys on key matrix is touched.
P46 terminal while one of G2 line keys on key matrix is touched.
35
P25
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P43, P44, P45 and
P46 terminal while one of G3 line keys on key matrix is touched.
P46 terminal while one of G3 line keys on key matrix is touched.
36
P24
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P43, P44, P45 and
P46 terminal while one of G4 line keys on key matrix is touched.
P46 terminal while one of G4 line keys on key matrix is touched.
37
P23
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P43, P44, P45 and
P46 terminal while one of G5 line keys on key matrix is touched.
P46 terminal while one of G5 line keys on key matrix is touched.
38
P22
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P43, P44, P45 and
P46 terminal while one of G6 line keys on key matrix is touched.
P46 terminal while one of G6 line keys on key matrix is touched.
39
P21
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P43, P44, P45 and
P46 terminal while one of G7 line keys on key matrix is touched.
P46 terminal while one of G7 line keys on key matrix is touched.
40
P20
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P43, P44, P45 and
P46 terminal while one of G8 line keys on key matrix is touched.
P46 terminal while one of G8 line keys on key matrix is touched.
41-56
P17-P00
OUT
Terminal not used.
57-60
P37-P34
OUT
Terminal not used.
61-72
SEG11-SEG0
OUT
Segment data signal.
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 (Pin No.)
LSI signal (Pin No.)
LCD (Pin No.)
SEG 11 (61) ............................... S12
SEG 5 (67) ................................. S6
SEG 10 (62) ............................... S11
SEG 4 (68) ................................. S5
SEG 9 (63) ............................... S10
SEG 3 (69) ................................. S4
SEG 8 (64) ............................... S9
SEG 2 (70) ................................. S3
SEG 7 (65) ............................... S8
SEG 1 (71) ................................. S2
SEG 6 (66) ............................... S7
SEG 0 (72) ................................. S1
73/74
VCC/VREF
IN
Connected to GND.
75
AVSS
IN
Connected to VC.
76
COM3
OUT
Terminal not used.
77
COM2
OUT
Common data signal.
Connected to LCD signal C3.
DESCRIPTION OF LS
I
LSI(IZA954DR)
The I/O signal of the LSI(IZA954DR) are detailed in the following table.
10
752M -
Figure C-4. Switches
Pin No.
Signal
I/O
Description
78
COM1
OUT
Common data signal.
Connected to LCD signal C2.
79
COM0
OUT
Common data signal.
Connected to LCD signal C1.
80
VL3
IN
Power source voltage input terminal.
Standard voltage for LCD.
DESCRIPTION OF LSI
LSI(IZA954DR)
The I/O signal of the LSI(IZA954DR) are detailed in the following table.
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.
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.
MONITORED LATCH SWITCH, STOP SWITCH
AND MONITOR SWITCH REMOVAL
AND MONITOR SWITCH REMOVAL
MONITOR SWITCH
STOP SWITCH
MONITORED
LATCH SWITCH
LATCH SWITCH
Tab
Post
Post
Post
Tab
Tab
1. CARRY OUT 3D CHECKS.
2. Remove the control panel assembly referring to
2. Remove the control panel assembly referring to
“CONTROL PANEL REMOVAL”.
3. Disconnect the leads from all switches.
4. Remove the two (2) screws holding the latch hook to the
4. Remove the two (2) screws holding the latch hook to the
oven cavity.
5. Remove the latch hook.
6. Push the retaining tab slightly and remove the switch.
6. Push the retaining tab slightly and remove the switch.
COMPONENT REPLACEMENT AND ADJUSTMENT
WIRING / RE-WIRING
11
752M -
COMPONENT REPLACEMENT AND ADJUSTMENT
DOOR REPLACEMENT
10
5
4
12
8
7
9
11
3
2
1
Choke Cover
Door Frame
Putty Knife
6
REMOVAL
1. Disconnect the power supply cord.
2. Open the door slightly.
3. Remove the choke cover taking care not to break clips
2. Open the door slightly.
3. Remove the choke cover taking care not to break clips
by inserting an iron plate (thickness of about 0.5mm)
or flat type screw driver to the gap between the choke
cover and door panel as shown Figure C-4 to free the
engaged parts.
or flat type screw driver to the gap between the choke
cover and door panel as shown Figure C-4 to free the
engaged parts.
4. Release choke cover from door panel.
5. Now choke cover is free.
5. Now choke cover is free.
Figure C-4. Door Disassembly
6. Release two (2) pins of door panel from two (2) holes
of upper and lower oven hinges by lifting up.
7.
1. Remove door assy by removing screws (4).
8. Release door panel from tabs of door frame and
remove door frame by sliding the door panel downward.
9. Now, door panel with inner sealer film is free.
10. Tear inner sealer film from door panel.
11. Now, door panel is free.
12. Slide latch head upward and remove it from door
10. Tear inner sealer film from door panel.
11. Now, door panel is free.
12. Slide latch head upward and remove it from door
frame with releasing latch spring from door frame and
latch head.
latch head.
13. Now, latch head and latch spring are free.
14.
14.
Remove Glass Stopper Screw (noting position of
stopper) and slide stopper down while lifting up.
stopper) and slide stopper down while lifting up.
15.
Slide glass towards Glass Stopper position and
then down towards the lower edge of the door
frame.
frame.
16.
Lift upper edge of glass, which will now be free
from upper clips and remove from lower clips.
17.
Refitting is a reversal of the above when refitting,
ensure the glass and the glass stopper is in the
original position.
original position.
RE-INSTALL
1. Re-install the outer door glass to the door frame with
the glass stopper.
2. Hold the glass stopper with the one (1) screw.
3. Re-install latch spring to the head. Re-install latch
3. Re-install latch spring to the head. Re-install latch
spring to the door frame. Re-install latch head to the
door frame.
door frame.
4. Re-install door panel to door frame by fitting tabs of
door frame to holes of door panel.
5. Put sealer film on door panel. Refer to “Inner Sealer
Film” and figure C-6, on how to handle the new film.
6. Catch two (2) pins of door panel on two (2) hole of
upper and lower oven hinges.
7. Re-install choke cover to door panel by pushing.
Note: After any service to the door;
(A) Make sure that monitored latch switch, stop
(A) Make sure that monitored latch switch, stop
switch and monitor switch are operating properly.
(Refer to chapter “Test Procedures”.).
(Refer to chapter “Test Procedures”.).
(B) An approved microwave survey meter should be
used to assure compliance with proper
microwave radiation emission limitation
standards.
microwave radiation emission limitation
standards.
After any service, make sure of the following :
1. Door latch heads smoothly catch latch hook through
latch holes and that latch head goes through center of
latch hole.
latch hole.
2. Deviation of door alignment from horizontal line of
cavity face plate is to be less than 1.0mm.
3. Door is positioned with its face pressed toward cavity
face plate.
4. Check for microwave leakage around door with an
approved microwave survey meter. (Refer to
Microwave Measurement Procedure.)
Microwave Measurement Procedure.)
Note:
The door on a microwave oven is designed to
act as an electronic seal preventing the leak-
age of microwave energy from oven cavity
during cook cycle. This function does not re-
quire that door be air-tight, moisture (conden-
sation)-tight or light-tight. Therefore, occasional
appearance of moisture, light or sensing of
gentle warm air movement around oven door
is not abnormal and do not of themselves,
indicate a leakage of microwave energy from
oven cavity.
act as an electronic seal preventing the leak-
age of microwave energy from oven cavity
during cook cycle. This function does not re-
quire that door be air-tight, moisture (conden-
sation)-tight or light-tight. Therefore, occasional
appearance of moisture, light or sensing of
gentle warm air movement around oven door
is not abnormal and do not of themselves,
indicate a leakage of microwave energy from
oven cavity.
Figure C-5. Door Replacement
I
INNER SEALER FILM
Installation
1. Tear away the backing film.
3. Put the pasted side of the inner sealer film on the door
3. Put the pasted side of the inner sealer film on the door
panel.
Pin
Pin
Lower
Oven
Hinge
Oven
Hinge
Lower Oven
Hinge
Hinge
Upper
Oven
Hinge
Oven
Hinge
Upper Oven
Hinge
Hinge
Door Panel
Choke Cover
Door film
Finger tab
Backing film
Figure C-6. Inner Sealer Film
12
752M -
SERVICING
approx. 1M ohm
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
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 in aluminium foil. Also wrap PW boards
containing them in aluminium foil.
containing 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.
2. 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 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.
controls (sensor-related ones included) of the
touch control panel while keeping it connected
to the oven.
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.
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
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.
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).
3. Servicing Tools
Tools required to service the touch control panel
assembly.
1) Soldering iron: 30W
assembly.
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
4. Other Precautions
1) Before turning on the power source of the control
unit, remove the aluminium foil applied for preventing
static electricity.
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.
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