Sharp R-753 (serv.man3) Service Manual ▷ View online
7
753M -
PROCEDURE
LETTER
COMPONENT TEST
TEST PROCEDURES
F
HIGH VOLTAGE RECTIFIER TEST
CARRY OUT 3D CHECKS.
Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier can
be tested using an ohmmeter set to its highest range. Connect the ohmmeter across the
terminal of the high voltage rectifier and note the reading obtained. Reverse the meter leads
and note this second reading.
The normal resistance is infinite in one direction and more than 100 k
be tested using an ohmmeter set to its highest range. Connect the ohmmeter across the
terminal of the high voltage rectifier and note the reading obtained. Reverse the meter leads
and note this second reading.
The normal resistance is infinite in one direction and more than 100 k
Ω
in the other direction.
CARRY OUT 4R CHECKS.
NOTE:
FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER, THE
BATTERIES OF THE MEASURING INSTRUMENT MUST HAVE A VOLTAGE AT
LEAST 6 VOLTS, BECAUSE OTHERWISE AN INFINITE RESISTANCE
MIGHT BE SHOWN IN BOTH DIRECTIONS.
BATTERIES OF THE MEASURING INSTRUMENT MUST HAVE A VOLTAGE AT
LEAST 6 VOLTS, BECAUSE OTHERWISE AN INFINITE RESISTANCE
MIGHT BE SHOWN IN BOTH DIRECTIONS.
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
The touch control section consists of the following units.
(1) Key Unit
(2) Control Unit (The Control Unit consists of Power Unit and
(2) Control Unit (The Control Unit consists of Power Unit and
CPU Unit).
The principal functions of these units and the signals com-
municated among them are explained below.
municated among them are explained below.
Key Unit
The key unit is composed of a matrix, signals generated in
the LSI are sent to the key unit through P20, P21, P22, P23,
P24, P25, P26 and P27.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P43, P44,
P45 and P46 to perform the function that was requested.
the LSI are sent to the key unit through P20, P21, P22, P23,
P24, P25, P26 and P27.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P43, P44,
P45 and P46 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, synchro-
nizing signal circuit and back light circuit.
power source circuit, relay circuit, buzzer circuit, synchro-
nizing 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 voltages necessary in the control
unit from the AC line voltage.
In addition, the synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.
In addition, the synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.
Symbol
Voltage
Application
VC
-5.2V
LSI(IC1)
4) Relay Circuit
A circuit to drive the magnetron, grill heating element,
fan motor, turntable motor and light the oven lamp.
fan motor, turntable motor and light the oven lamp.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (key touch sound and completion
sound).
audible sounds (key 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) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
8
753M -
DESCRIPTION OF LSI
LSI(IXA028DR)
The I/O signal of the LSI(IXA028DR) 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.
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.
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.
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.
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.
- 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.
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.
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.
into P43.
24
INT0
IN
Signal synchronized with commercial power source frequency.
This is the basic timing for time process-
ing of LSI.
ing of LSI.
25
P41
OUT
Terminal not used.
20.0 msec.
H : GND
L : -5V
9
753M -
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(IXA028DR)
The I/O signal of the LSI(IXA028DR) are detailed in the following table.
10
753M -
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(IXA028DR)
The I/O signal of the LSI(IXA028DR) 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
SW2
SW2
STOP SWITCH
SW3
SW3
MONITORED
LATCH SWITCH
SW1
LATCH SWITCH
SW1
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
Click on the first or last page to see other R-753 (serv.man3) service manuals if exist.