R-874 (serv.man3). Control pannel assembly, component replacement procedure and leakage measurement — Sharp Home Appliance Service Manual (repair manual)

Model
R-874 (serv.man3)
Pages
13
Size
429.78 KB
Type
PDF
Document
Service Manual
Brand
Device
Home Appliance / Microwave Oven / Control pannel assembly, component replacement procedure and leakage measurement
File
r-874-sm3.pdf
Date

View Sharp R-874 (serv.man3) Service Manual online

R-874M - 18
  TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
initial state when power is supplied.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (key touch sound and completion
sound).
6) Stop Switch
A switch to "tell" the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, grill heating element, bottom
heating element,  convection motor, fan motor, turnta-
ble motor, touch control transformer and  light the oven
lamp.
8) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LD1 - LD10).
9)  Indicator Circuit
This circuit consists 7-digits, 39-segments and 3-com-
mon electrodes using a Liquid Crystal Display.
10) 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 LSI.
The LSI 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) Key Unit
(2) Control Unit (The Control unit consists of Power unit
and CPU unit.)
The principal functions of these units and signals commu-
nicated 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 from P40, P41, P72, P73
P74, P75, P76 and P77.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P44 - P47
to perform the function that was requested.
Control Unit
Control unit consists of LSI, power source circuit, synchro-
nizing signal circuit, ACL circuit, buzzer circuit, relay
circuit, temperature measurement circuit, indicator circuit
and back light circuit.
1) LSI
This LSI controls the temperature measurement sig-
nal, key strobe signal, relay driving signal for oven
function and indicator signal.
2) Power Source Circuit
This circuit generates voltage necessary in the control
unit.
Symbol
Voltage
Application
VC
-5.2V
LSI(IC1)
3) 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.
4) ACL
A circuit to generate a signal which resets the LSI to the
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R-874M - 19
  DESCRIPTION OF LSI
A
B
C
H: GND
L
0.12 sec
2.4 sec
1.2 sec
1.2 sec
20 msec.
H : GND
L (-5V)
1
C1
IN
Terminal not used.
2
VL1
IN
Power source voltage input terminal.
Standard voltage for LCD.
3
AN7
IN
Terminal to change the on timing of the cook relay (RY2).
4-5
AN6-AN5
IN
Heating constant compensation terminal.
6
AN4
OUT
Terminal not used.
7
AN3
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.
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
AN1-AN0
OUT
Terminal not used.
11
P57
OUT
Timing signal output terminal for temperature measurement(OVEN
THERMISTOR).
"H" level (GND) : Thermistor OPEN timing.
"L" level (-5V) : Temperature measuring timing. (Convection cooking)
12
P56
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, or when the
preheating hold time (30 minutes) is
elapsed.
13
P55
OUT
Timing signal output terminal for temperature measurement(OVEN
THERMISTOR).
"H" level (GND) : Thermistor OPEN timing.
"L" level (-5V) : Temperature measuring timing. (Convection cooking)
14-18
P54-P50
OUT
Terminal not used.
19
P47
IN
Signal coming from touch key.
When any one of G12 line keys on key matrix is touched, a corresponding signal
from P40, P41, P72, P73, P74, P75, P76 and P77 will be input into P47. When no
key is touched, the signal is held at "L" level.
20
P46
IN
Signal similar to P47.
When any one of G11 line keys on key matrix is touched, a corresponding signal
will be input into P46.
21
P45
IN
Signal similar to P47.
When any one of G10 line keys on key matrix is touched, a corresponding signal
will be input into P45.
22
P44
IN
Signal similar to P47.
When any one of G9 line keys on key matrix is touched, a corresponding signal will
be input into P44.
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
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P44 - P47 terminal
while one of G8 line key on matrix is touched.
LSI(IXA094DR)
The I/O signal of the LSI(IXA094DR) are detailed in the following table.
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R-874M - 20
LSI(IXA094DR)
The I/O signal of the LSI(IXA094DR) are detailed in the following table.
  DESCRIPTION OF LSI
Pin No.
Signal
I/O
Description
ON/OFF time ratio in Mi-
cro cooking
(a. 32second time base)
ON/OFF time ratio in Mi-
cro cooking
(a. 48second time base)
MICRO
ON
OFF
COOK
100%
32 sec.
0 sec.
70%
24 sec.
8 sec.
50%
18 sec. 14 sec.
30%
12 sec. 20 sec.
10%
6 sec. 26 sec.
MICRO
ON
OFF
COOK
100%
48 sec.
0 sec.
70%
36 sec. 12 sec.
50%
26 sec. 22 sec.
30%
16 sec. 32 sec.
10%
8 sec. 40 sec.
Power output
ON time
OFF time
100 %
48 sec.
0 sec.
90 %
44 sec.
4 sec.
80 %
40 sec.
8 sec.
70 %
36 sec.
12 sec.
60 %
32 sec.
16 sec.
50 %
26 sec.
22 sec.
40 %
22 sec.
26 sec.
30 %
16 sec.
32 sec.
20 %
12 sec.
36 sec.
10 %
8 sec.
40 sec.
During cooking
L
H
20 msec.
26
P40
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P44 - P47 terminal
while one of G7 line key on matrix is touched.
27
P77
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P44 - P47 terminal
while one of G6 line key on matrix is touched.
28
P76
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P44 - P47 terminal
while one of G5 line key on matrix is touched.
29
P75
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P44 - P47 terminal
while one of G4 line key on matrix is touched.
30
P74
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P44 - P47 terminal
while one of G3 line key on matrix is touched.
31
P73
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P44 - P47 terminal
while one of G2 line key on matrix is touched.
32
P72
OUT
Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to P44 - P47 terminal
while one of G1 line key on matrix is touched.
33
P71
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.
34
P70
IN
Connected to VC.
35
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.
36
P81
OUT
Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay
(RY2). In 100% 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.
37
P80
OUT
Grill (TOP) heating element driving signal.
To turn on and off the grill heating
element relay (RY3). "L" level during
grill cooking, convection cooking or
dual cooking, "H" level otherwise.
The heater relay turns on and off
within a 48 second time base in
accordance with the special program
in LSI.
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R-874M - 21
LSI(IXA094DR)
The I/O signal of the LSI(IXA094DR) are detailed in the following table.
  DESCRIPTION OF LSI
Pin No.
Signal
I/O
Description
Power output
ON time
OFF time
100 %
48 sec.
0 sec.
90 %
44 sec.
4 sec.
80 %
40 sec.
8 sec.
70 %
36 sec.
12 sec.
60 %
32 sec.
16 sec.
50 %
26 sec.
22 sec.
40 %
22 sec.
26 sec.
30 %
16 sec.
32 sec.
20 %
12 sec.
36 sec.
10 %
8 sec.
40 sec.
ON
OFF
During
cooking
L
GND
H.
(Convection or dual cooking)
ON
OFF
During cooking or for awhile after convection, 
grill (top and bottom grill ) or dual. 
L
GND
H.
38
XIN
IN
Internal clock oscillation frequency input setting.
The internal clock frequency is set by inserting the ceramic filter oscillation circuit
with respect to XOUT terminal.
39
XOUT
OUT
Internal clock oscillation frequency control output.
Output to control oscillation input of XIN.
40
VSS
IN
Power source voltage: -5V.
VC voltage of power source circuit input.
41
P27
OUT
Bottom heating element driving signal.
To turn on and off the relay (RY4). "L"
level during grill cooking, convection
cooking or dual cooking, "H" level
otherwise.
The heater relay turns on and off within
a 48 second time base in accordance
with the special program in LSI.
42
P26
OUT
Convection motor driving signal.
To turn on and off shut-off relay(RY7). "L"
level during convection or dual cooking "H"
level otherwise. (Relay RY7 does not turn on
at preheating mode.)
43
P25
OUT
Fan motor driving signal.
To turn on and off the fan motor relay RY6.  "L"
level during cooking, or for a while after
convection, grill (top and bottom grill) or dual
cooking. "H" level otherwise.
44
P24
OUT
Terminal not used.
45
P23
OUT
Touch control transformer driving signal.
To turn on and off the shut off relay (RY5). If the oven has not been used for more
than 3 minutes, the relay RY5 will be turned off. The relay RY5 will be turned on
when the oven door is opened and closed.
46-48
P22-P20
OUT
Terminal not used.
49-50
P17-P16
IN
Terminal to change functions according to the model.
51-80
SEG39-SEG10
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 0 (90) .................... SEG39 (51)
SEG21 (69) ................. SEG19 (19)
SEG 1 (89) .................... SEG38 (50)
SEG22 (68) ................. SEG18 (18)
SEG 2 (88) .................... SEG37 (49)
SEG23 (67) ................. SEG17 (17)
SEG 3 (87) .................... SEG36 (48)
SEG24 (66) ................. SEG16 (16)
SEG 4 (86) .................... SEG35 (47)
SEG25 (65) ................. SEG15 (15)
SEG 5 (85) .................... SEG34 (46)
SEG26 (64) ................. SEG14 (14)
SEG 6 (84) .................... SEG33 (45)
SEG27 (63) ................. SEG13 (13)
SEG 7 (83) .................... SEG32 (44)
SEG28 (62) ................. SEG12 (12)
SEG 8 (82) .................... SEG31 (43)
SEG29 (61) ................. SEG11 (11)
SEG10 (80) ................... SEG30 (30)
SEG30 (60) ................. SEG10 (10)
SEG11 (79) ................... SEG29 (29)
SEG31 (59) ................... SEG 9 ( 9)
SEG12 (78) ................... SEG28 (28)
SEG32 (58) ................... SEG 8 ( 8)
SEG13 (77) ................... SEG27 (27)
SEG33 (57) ................... SEG 7 ( 7)
SEG14 (76) ................... SEG26 (26)
SEG34 (56) ................... SEG 6 ( 6)
SEG15 (75) ................... SEG25 (25)
SEG35 (55) ................... SEG 5 ( 5)
SEG16 (74) ................... SEG24 (24)
SEG36 (54) ................... SEG 4 ( 4)
SEG17 (73) ................... SEG23 (23)
SEG37 (53) ................... SEG 3 ( 3)
SEG18 (72) ................... SEG22 (22)
SEG38 (52) ................... SEG 2 ( 2)
SEG19 (71) ................... SEG21 (21)
SEG39 (51) ................... SEG 1 ( 1)
SEG20 (70) ................... SEG20 (20)
R-874 S/MANUAL
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