R-8740 (serv.man9). Control panel assembly — Sharp Home Appliance Service Manual (repair manual)

Model
R-8740 (serv.man9)
Pages
7
Size
465.95 KB
Type
PDF
Document
Service Manual
Brand
Device
Home Appliance / Microwave Oven / Control panel assembly
File
r-8740-sm9.pdf
Date

View Sharp R-8740 (serv.man9) Service Manual online

R-8740M  - 21
   
 TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
6) I-2 (Memory Processor)
This is a memory IC, responsible for memory
function.
7) Display Circuit
This is a circuit for driving light emitting diode by I-1
output.
8) Key Input Circuit
This is a circuit for transmitting key input information
to I-1.
9) Relay Driving Circuit
This is a circuit for driving output relay by I-1 output.
10) Door Sensing Switch Circuit
This is a circuit for driving I-1 to detect door opening/
closing.
11) Buzzer Circuit
The buzzer is responsive to signals from the I-1 to
emitaudible sounds (key touch sound and
completion sound).
12) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LD1 - LD4).
13) Cooking Mode Indicator Circuit
A circuit to drive cooking mode indicator (Light
emitting diodes LD6 - LD9).
14) Temperature Measurement Circuit : (OVEN
THERMISTOR)
The temperature in the oven cavity is sensed by the
thermistor. The variation of resistance according to
sensed temperature is detected by the temperature
measurement circuit and the result applied to I-1.
The I-1 uses this information to control the relay and
display units.
The touch control section consists of the following units
as shown in the touch control panel circuit.
(1) Control Unit
(2) Key Unit
The principal functions of these units and the signals
communicated among them are explained below.
1.  Control Unit
Signal of key touch and oven function control are all
processed by one microcomputer.
1) Power Supply Circuit
This circuit changes output voltage at the secondary
side of the low voltage (T1) transformer to voltages
required at each part by full wave rectifying circuit,
constant voltage circuit, etc..
Symbol
Voltage
Application
VC
-5.0V
I-1
2) ACL Circuit
This is an Auto-clear Circuit, i.e., a reset circuit,
which enables I-1 to be activated from initial state.
3) Power SYNC Signal Generating Circuit
This is a circuit for generating power SYNC
(synchronizing) signal by virtue of the secondary
side output of transformer T1.
This signal is used for a basic frequency to time
processing and so on.
4) Clock Circuit
This is a circuit for controlling clock frequency
required for operating I-1.
5) I-1 (Main Processor)
This is a one-chip microcomputer, responsible for
controlling the entire control unit.
R-8740M  - 22
The key unit is composed of a matrix circuit in which when a key it touched, one of signals P12-P17 generated
by the LSI, is passed through the key and returned to the LSI as one of signals P20-P23.
This model has 10 Memory pads.
When the oven is shipped, Memory pad 1 to 10 are set as follows: Table 1.
Table 1. Preset memory contents
Memory No.
MENU
WEIGHT
STAGE
MODE
PAUSE
COOKING TIME
REDUCE
FACTOR
1
PIZZA-THIN
350G
1)
70% MW / TG
-
2'30
0.8
2)
TG / BG
5'00
TTL
7'30
2
PIZZA-THIN
450G
1)
70% MW / TG
-
2'40
0.9
2)
TG
1'00
3)
TG / BG
4'30
TTL
8'10
3
PIZZA BAGUETTE
250G
1)
100% MW / TG
-
2'00
0.85
2)
TG
3'00
3)
TG / BG
2'30
TTL
7'30
4
CIABATTA PIZZA
185G
1)
70% MW / TG
-
2'00
0.8
2)
TG / BG
3'30
3)
TG
1'30
TTL
7'00
5
GARLIC BREAD
170G
1)
70% MW / TG
-
1'30
0.9
2)
TG / BG
2'30
3)
30% MW / BG
1'00
TTL
5'00
6
CHEESE BURGER
145G
1)
50% MW / BG
-
3'00
0.9
2)
TG
2'00
TTL
5'00
7
SAUSAGE
250G
1)
TG / BG
YES
5'00
0.9
2)
TG / BG
-
5'00
TTL
10'00
8
SOUP / CASSEROLE
200G
1)
100% MW
-
1'30
0.9
9
DINNER PLATES
480G
1)
100% MW
YES
5'00
0.9
2)
100% MW
5'00
TTL
10'00
0
PIQUANT
300G
1)
10% MW
-
3'00
0.8
PASTRY
2)
10% MW / 200˚C
12'00
TTL
15'00
TG : Top heater.  BG : Bottom heater.  MW : Microwave
How to set the preset memory contents (For only reference)
When the memory IC (I-2) is exchanged, it is not necessary to set the preset memory contents for SEEG
model. Because the initial memory IC (I-2) has been set them.
1) To set the preset memory contents for SEEG model.
* You can input for 1 min. from plug in.
PAD
DISPLAY
INDICATOR and LED
PHONE
( PLUG IN )
. 0
LOCK
TIME REDUCE
CONV
MICRO
( within 2 sec. )
(within 1 min. )
BOTTOM GRILL
C o n t
BTM
MEMORY
      b d
KEY UNIT
R-8740M  - 23
    LSI(IX091DR)
    The I/O signal of the LSI(IX091DR) are detailed in the following table.
Pin No.
Signal
I/O
Description
1-2
VL2-VL1
IN
Power source voltage input terminal.
Standard voltage for LCD.
3-5
AN7-AN5
IN
Terminal to change functions according to the Model.
DC voltage in accordance with the Model in operation is applied to set up its
function.
6
AN4
IN
Temperature measurement input: OVEN THERMISTOR.
By inputting DC voltage corresponding to the temperature detected by the
thermistor, this input is converted into temperature by the A/D converter built
into the LSI.
7
AN3
IN
Terminal not used.
8
AN2
IN
Input signal which communicates the door open/close information to LSI.
Door closed; "H" level signal.
Door opened; "L" level signal.
9-10
P61-P60
OUT
Timing signal output terminal for temperature measurement(OVEN
THERMISTOR)
"H" level (GND) : Thermistor OPEN timing.
"L" level (-5V) : Temperature measuring timing. (Convection cooking)
11
P57
IN
Terminal not used.
12
P56
OUT
Oven lamp and turntable motor driving signal(Square Waveform : 50Hz).
To turn on and off shut-off relay
(RY1). The square waveform voltage
is delivered to the relay (RY1) driving
circuit .
13
P55
OUT
Terminal not used.
14
P54
OUT
Signal to sound buzzer.
A: key touch sound.
B: Completion sound.
C: When the temperature of the oven
cavity reaches the preset temperature
in the preheating mode.
D: When "SOUND ON" is set with the
SOUND key. When the MEMORY key
is continued to push for more than 5
seconds and the memory setting
condition is set.
15
P53
OUT
Terminal not used.
16
P52
OUT
Fan motor driving signal.
To turn on and off the fan motor relay
RY5. "L" level during cooking, or for 90
seconds after manual cooking or 65
seconds after memory cooking (in case
where the same memory cooking is
operated for more than 10 minutes), or
until the oven cavity has been cooled
after convection or dual  cooking.
 17
P51
OUT
Bottom heater driving signal.
To turn on and off the bottom relay
(RY4). "L" level during grill (BOTTOM
HEATER, TOP AND BOTTOM) cooking
or dual  (MICRO + BOTTOM) cooking or
convection cooking. "H" level otherwise.
 18
P50
OUT
Convection motor driving signal.
To turn on and off shut-off relay (RY7).
"L" level during CONVECTION; "H" level
otherwise.
 DESCRIPTION OF LSI
20 msec
During cooking
H
L
A
B
C
H: GND
L
0.12 sec
2.4 sec
1.2 sec
1.2 sec
D
0.08 sec
0.08 sec
0.08 sec
ON
OFF
During cooking, or for 90 sec.
after manual cooking or 65 sec.
after memory cooking, or until
the oven cavity has been cooled
after convection or dual cooking.
H : GND
L : -5V
ON
OFF
During
cooking
L
GND
H.
(Convection)
ON
OFF
During
cooking
L
GND
H.
(Grill, dual or convection)
R-8740M  - 24
Pin No.
Signal
I/O
Description
ON/OFF time ratio in Micro
cooking
(a. 32second time base)
ON/OFF time ratio in Micro
cooking
(a. 48second time base)
MICRO
ON
OFF
COOK
100%
32sec.
0sec.
70%
24sec.
8sec.
50%
18sec.
14sec.
30%
12sec.
20sec.
10%
6sec.
26sec.
MICRO
ON
OFF
COOK
100%
48sec.
0sec.
70%
36sec.
12sec.
50%
26sec.
22sec.
30%
16sec.
32sec.
10%
8sec.
40sec.
19
P47
OUT
Grill heater (TOP HEATER) driving signal.
To turn on and off the grill heater relay
(RY3). "L" level during grill (TOP
GRILL, TOP AND BOTTOM) cooking
or dual  (MICRO + TOP) cooking or
convection cooking. "H" level
otherwise.
20
P46
OUT
Magnetron high-voltage circuit driving signal.
To turn on and off the cook
relay (RY2). In 100%
POWER operation, 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.
21
P45
OUT
Memory (I-2) clock output.
22
P44
IN/OUT
Memory (I-2) data input/output.
23
INT1
OUT
Terminal not used.
24
INT0
IN
Signal to synchronized LSI with commercial power source
frequency(50Hz).
This is basic timing for time processing of LSI.
25
P41
IN
Terminal not used.
26
P40
IN
Connected to VC.
27
RESET
IN
Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is applied.
Temporarily set to "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: -5V.
VC voltage of power source circuit input.
33-36
P27-P24
OUT
Terminal not used.
37
P23
IN
Signal coming from touch key.
When any one of G4 line keys on key matrix is touched, a corresponding
signal   from P17 - P12 will be input into P23. When no key is touched, the
signal is held at "H" level.
38
P22
IN
Signal similar to P23.
When any one of G3 line keys on key matrix is touched, a corresponding
signal will be input into P22.
39
P21
IN
Signal similar to P23.
When any one of G2 line keys on key matrix is touched, a corresponding
signal will be input into P21.
40
P20
IN
Signal similar to P23.
When any one of G1 line keys on key matrix is touched, a corresponding
signal will be input into P20.
   
 
DESCRIPTION OF LSI
 LSI(IX091DR)
    The I/O signal of the LSI(IX091DR) are detailed in the following table.
ON
OFF
During
cooking
L
GND
H.
(Grill,dual or convection)
20 msec
H : GND
L (-5V)
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