Sharp R-884 (serv.man2) Service Manual ▷ View online
R-884M - 17
PROCEDURE
LETTER
COMPONENT TEST
O
RELAY TEST
TEST PROCEDURES
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between Pin Nos. 1 and 3 of the 4 pin connector (E) on
the control unit with an A.C. voltmeter.
The meter should indicate 230-240 volts, if not check oven circuit.
the control unit with an A.C. voltmeter.
The meter should indicate 230-240 volts, if not check oven circuit.
Relay Test
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation, grill
operation, convection operation or dual operation.
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation, grill
operation, convection operation or dual operation.
DC. voltage indicated .......... Defective relay.
DC. voltage not indicated .... Check diode which is connected to the relay coil. If diode is good,
DC. voltage not indicated .... Check diode which is connected to the relay coil. If diode is good,
control unit is defective.
RELAY SYMBOL
OPERATIONAL VOLTAGE
CONNECTED COMPONENTS
RY1
Approx. 18.0V D.C.
Oven lamp / Turntable motor
RY2
Approx. 18.0V D.C.
High voltage transformer
RY3
Approx. 24.0V D.C.
Grill (Top) heating element
RY4
Approx. 24.0V D.C.
Bottom heating element
RY5
Approx. 24.0V D.C.
Touch control transformer
RY6
Approx. 24.0V D.C.
Fan motor
RY7
Approx. 24.0V D.C.
Convection motor
CARRY OUT 4R CHECKS.
P
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(PWB) IS OPEN
(PWB) IS OPEN
NOTE: *At the time of these repairs, make a
visual inspection of the varistor for burn-
ing damage and examine the trans-
former with tester for the presence of
layer short circuit (check primary coil
resistance).
If any abnormal condition is detected,
replace the defective parts.
ing damage and examine the trans-
former with tester for the presence of
layer short circuit (check primary coil
resistance).
If any abnormal condition is detected,
replace the defective parts.
CARRY OUT 4R CHECKS.
To protect the electronic circuits, this model is provided with a fine foil pattern added to the input circuit
on the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide
given below for repair.
Problem: POWER ON, indicator does not light up.
on the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide
given below for repair.
Problem: POWER ON, indicator does not light up.
CARRY OUT 3D CHECKS.
STEPS
OCCURRENCE
CAUSE OR CORRECTION
1
The rated AC voltage is not present between
Check supply voltage and oven power cord.
Pin Nos. 1 and 3 of the 4-pin connector (E).
2
The rated AC voltage is present at primary
Low voltage transformer or secondary circuit defective.
side of low voltage transformer.
Check and repair.
3
Only pattern at "a" is broken.
*Insert jumper wire J1 and solder.
(CARRY OUT 3D CHECKS BEFORE REPAIR.)
4
Pattern at "a" and "b" are broken.
*Insert the coil RCILF2003YAZZ between "c" and "d".
(CARRY OUT 3D CHECKS BEFORE REPAIR.)
7
9
1
RY4
(J1)
(J2)
FM
POWER
a
b
c
d
F
CN - E
CN - A
VRS1
RY6
R-884M - 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).
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.
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).
LD1 - LD10).
9) Indicator Circuit
This circuit consists 7-digits, 39-segments and 3-com-
mon electrodes using a Liquid Crystal Display.
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 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.
shown in the touch control panel circuit.
(1) Key Unit
(2) Control Unit (The Control unit consists of Power 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.
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.
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.
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.
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.
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.
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
R-884M - 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.
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.
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.
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)
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
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.
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)
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.
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.
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.
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.
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.
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.
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.
The I/O signal of the LSI(IXA094DR) are detailed in the following table.
R-884M - 20
LSI(IXA094DR)
The I/O signal of the LSI(IXA094DR) are detailed in the following table.
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)
cro cooking
(a. 32second time base)
ON/OFF time ratio in Mi-
cro cooking
(a. 48second time base)
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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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