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Model
R-752M (serv.man2)
Pages
23
Size
328.08 KB
Type
PDF
Document
Service Manual
Brand
Device
Home Appliance / Microwave Oven
File
r-752m-sm2.pdf
Date

Sharp R-752M (serv.man2) Service Manual ▷ View online

8
752M -
DESCRIPTION OF LSI
LSI(IZA954DR)
The I/O signal of the LSI(IZA954DR) are detailed in the following table.
Pin No.
Signal
I/O
Description
20.0 msec.
During cooking
H : GND
L : -5V
100P
H : GND
L : -5V
H : GND
L : -5V
70P
ON
ON
OFF
OFF
OFF
24 sec.
8 sec.
A
B
0.12 sec.
2.4 sec.
H : GND
L : -5V
H : GND
L : -5V
(Grill or dual)
ON
OFF
During
cooking
L
GND
H.
1-2
VL2-VL1
IN
Power source voltage input terminal.
Standard voltage for LCD.
3-6
AN7-AN4
IN
Terminal to change cooking input 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 cooking constant.
7-8
P63-P62
OUT
Terminal not used.
9
AN1
IN
To input signal which communicates the door open/close information to LSI.
Door close "H" level signal (0V). Door open "L" level signal (-5V).
10
P60
OUT
Terminal not used.
11-13
P57-P55
OUT
Terminal not used.
14
CNTR0
OUT
Signal to sound buzzer (2.0 kHz).
A: key touch sound.
B: Completion sound.
15
P53
OUT
Oven lamp, fan motor and turntable motor driving signal
To turn on and off shut off relay (RY1).
The square waveform voltage is deliv-
ered to the RY1 driving circuit, RY2 and
RY3 control circuit.
16
P52
OUT
Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay (RY3).
The signals holds "L" level during micro-
wave cooking and "H" level while not
cooking. In other cooking modes (vari-
able cooking) the signal turns to "H" level
and "L" level in repetition according to
the power level.
(ON and OFF times for other power level.)
17
P51
OUT
Grill heating element driving signal
To turn on and off the grill heating ele-
ment relay (RY2). "L" level during grill
cooking or dualcooking; "H"level
othewise.
18
P50
OUT
Terminal not used.
19
P47
OUT
Terminal not used.
20
P46
IN
Signal coming from touch key.
When either G12 line on key matrix is touched, a corresponding signal out of P20
- P27 will be input into P46. When no key is touched, the signal is held at "H" level.
21
P45
IN
Signal similar to P46.
When either G11 line on key matrix is touched, a corresponding signal will be input
into P45.
22
P44
IN
Signal similar to P46.
When either G10 line on key matrix is touched, a corresponding signal will be input
into P44.
23
P43
IN
Signal similar to P46.
When either G9 line on key matrix is touched, a corresponding signal will be input
into P43.
24
INT0
IN
Signal synchronized with commercial power source frequency.
This is the basic timing for time process-
ing of LSI.
25
P41
OUT
Terminal not used.
20.0 msec.
H : GND
L : -5V
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.)
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)
b)
Parts that become hot.
(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)
d)
Movable parts.
(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
MONITOR SWITCH
STOP SWITCH
MONITORED
LATCH SWITCH
Tab
Post
Post
Post
Tab
Tab
1. CARRY OUT 3D CHECKS.
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
oven cavity.
5. Remove the latch hook.
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
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.
4. Release choke cover  from door panel.
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
frame with releasing latch spring from door frame and
latch head.
13. Now, latch head and latch spring are free.
14.
Remove Glass Stopper Screw (noting position of
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.
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.
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
spring to the door frame. Re-install latch head to the
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
switch and monitor switch are operating properly.
(Refer to chapter “Test Procedures”.).
(B) An approved microwave survey meter should be
used to assure compliance with proper
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.
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.)
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.
             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
panel.
Pin
Pin
Lower
Oven
Hinge
Lower Oven
Hinge
Upper
Oven
Hinge
Upper Oven
Hinge
Door Panel
Choke Cover
Door film
Finger tab
Backing film
 Figure C-6. Inner Sealer Film
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