Sharp R-4G75M (serv.man7) Service Manual ▷ View online
15
R-4G75(W)M
R-4G75(B)M
R-4G75(B)M
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER
COMPONENT TEST
Checking the initial sensor cooking condition
(1) The oven should be plugged in at least five minutes before sensor cooking.
(2) Room temperature should not exceed 95˚F(35˚C).
(3) The unit should not be installed in any area where heat and steam are generated. The unit should not
(1) The oven should be plugged in at least five minutes before sensor cooking.
(2) Room temperature should not exceed 95˚F(35˚C).
(3) The unit should not be installed in any area where heat and steam are generated. The unit should not
be installed, for example, next to a conventional surface unit. Refer to the "INSTALLATION Instructions"
.
.
(4) Exhaust vents are provided on the back of the unit for proper cooling and air flow in the cavity. To permit
adequate ventilation, be sure to install so as not to block these vents. There should be some space for
air circulation.
air circulation.
(5) Be sure the exterior of the cooking container and the interior of the oven are dry. Wipe off any moisture
with a dry cloth or paper towel.
(6) The Sensor works with food at normal storage temperature.For example, chicken pieces would be at
refrigerator temperature and canned soup at room temperature.
(7) Avoid using aerosol sprays or cleaning solvents near the oven while using Sensor settings. The sensor
will detect the vapor given of by the spray and turn off before food is properly cooked.
(8) After 25 minutes if the sensor has not detected the vapor of the food, ERROR will appear and the oven
will shut off.
Water load cooking test
Make sure the oven has been plugged in at least five minutes before checking sensor cook operation. The
cabinet should be installed and screws tightened.
(1) Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup.
(2) Place the container on the center of tray in the oven cavity.
(3) Close the door.
Make sure the oven has been plugged in at least five minutes before checking sensor cook operation. The
cabinet should be installed and screws tightened.
(1) Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup.
(2) Place the container on the center of tray in the oven cavity.
(3) Close the door.
To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on
the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide
given below for repair.
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
P
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING
BOARD(PWB) IS OPEN.
BOARD(PWB) IS OPEN.
STEPS
OCCURANCE
CAUSE OR CORRECTION
1
The rated AC voltage is not present at
POWER terminal of CPU connector (CN-A)
Check supply voltage and oven power cord. Please use
term "Low voltage transformer" when refering to
transformer T1
2
The rated AC voltage is present at primary
side of low voltage transformer.
Low voltage transformer or secondary circuit defective.
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)
NOTE: At the time of these repairs, make a visual
inspection of the varistor for burning damage
and examine the transformer with tester for
the presence of layer short-circuit (check
primary coil resistance). If any abnormal
condition is detected, replace the defective
parts.
and examine the transformer 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
a
d
c
b
OL TTM FAN M
POWER
CN–A
(J1)
VRS1
RY1
D81
(R110)(J11)
(J10)
D82
RY2
17
1
3
5
Q
AH SENSOR TEST
16
R-4G75(W)M
R-4G75(B)M
R-4G75(B)M
(4) Touch INSTANT COOK pad five times. Now, the oven is in the sensor cooking condition. IC-5 will
appear in the display.
(5) The oven will operate for the first 16 seconds, without generating microwave energy.
NOTE: ERROR will appear if the door is opend or STOP/CLEAR pad is touched during first stage of sensor
NOTE: ERROR will appear if the door is opend or STOP/CLEAR pad is touched during first stage of sensor
cooking
(6) After approximately 16 seconds, microwave energy is produced, oven should turn off when water is
boiling (bubling).
If the oven does not turn off, replace the AH sensor or check the control unit, refer to explanation below.
If the oven does not turn off, replace the AH sensor or check the control unit, refer to explanation below.
TESTING METHOD FOR AH SENSOR AND/OR CONTROL UNIT
To determine if the sensor is defective, the simplest method is to replace it with anew replacement sensor.
(1) Disconnect oven from power supply and remove outer case.
(2) Discharge the high voltage capacitor.
(3) Remove the AH sensor.
(4) Install the new AH sensor.
(5) Re-install the outer case.
(6) Reconnect the oven to the power supply and check the sensor cook operation proceed as follows:
(1) Disconnect oven from power supply and remove outer case.
(2) Discharge the high voltage capacitor.
(3) Remove the AH sensor.
(4) Install the new AH sensor.
(5) Re-install the outer case.
(6) Reconnect the oven to the power supply and check the sensor cook operation proceed as follows:
6-1. Fill approxmately 200 milliliters (7.2 oz) of tap water in a 1000 milililiter measuring cup.
6-2. Place the container on the center of tray in the oven cavity.
6-3. Close the door.
6-2. Place the container on the center of tray in the oven cavity.
6-3. Close the door.
CHECKING CONTROL UNIT
(1) Disconnect oven from power supply and remove outer case.
(2) Discharge the high voltage capacitor.
(3) Disconnect the wire leads from the cook relay.
(4) Disconnect the sensor connector that is mounted to control panel.
(5) Then connect the dummy resistor circuit (see fig.) to the sensor connector of control panel.
(6) Reconnect the oven to the power supply and check the sensor cook operation proceed as follows:
(2) Discharge the high voltage capacitor.
(3) Disconnect the wire leads from the cook relay.
(4) Disconnect the sensor connector that is mounted to control panel.
(5) Then connect the dummy resistor circuit (see fig.) to the sensor connector of control panel.
(6) Reconnect the oven to the power supply and check the sensor cook operation proceed as follows:
6-1. Touch INSTANT COOK pad five times.
6-2. The control panel is in the sensor cooking operation.
6-3. After approxmately 20 seconds, push plunger of select switch. This condition is same as judgement
6-2. The control panel is in the sensor cooking operation.
6-3. After approxmately 20 seconds, push plunger of select switch. This condition is same as judgement
by AH sensor.
6-4. After approxmately 3 seconds, cooking operation turns off, an audible signal will sound, and the
display will then revert to the time of day.
If the above is not the case, the control unit is probably defective.
If the above is proper, the AH sensor is probably defective
If the above is proper, the AH sensor is probably defective
R1,R2 : 22 ohm
±
1% 1/2W
R3 : 10k ohm
±
5% 1/2W
R4 : 1M ohm
±
5% 1/2W
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER
COMPONENT TEST
Sensor Dummy Resistor Circuit
Plunger
NC
NO
COM
COM
NO
NC
R3
R4
R1
R2
1
2
3
F-1
F-2
F-3
To connector (F)
on Control Unit.
on Control Unit.
CONNECTOR
17
R-4G75(W)M
R-4G75(B)M
R-4G75(B)M
The touch control section consists of the following units
as shown in the touch control panel circuit.
as shown in the touch control panel circuit.
(1) Key Unit
(2) Control Unit
(2) Control Unit
The principal functions of these units and the signals
communicated among them are explained below.
communicated 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 P05,P06,P07,
P10,P12 and P14. When a key pad is touched, a signal is
completed through the key unit and passed back to the
LSI through P24,P25,P26 and P27 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 through P05,P06,P07,
P10,P12 and P14. When a key pad is touched, a signal is
completed through the key unit and passed back to the
LSI through P24,P25,P26 and P27 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 and indica-
tor circuit.
Control unit consists of LSI, power source circuit, synchro-
nizing signal circuit, ACL circuit, buzzer circuit and indica-
tor circuit.
1) LSI
This LSI controls the key strobe signal, relay driving
signal for oven function and indicator signal.
signal for oven function and indicator signal.
2) Power Source Circuit
This circuit generates voltages necessary in the control
unit.
unit.
Symbol
Voltage
Application
VC
-5V
LSI(IC1)
VP
-26V
Fluorescent display tube : Grid
and anode voltage
and anode voltage
VF1
3Vac
Filament of fluorescent display
tube
tube
VF2
(VF1 to VF2 voltage)
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 Circuit
A circuit to generate a signal which resets the LSI to the
initial state when power is supplied.
initial state when power is supplied.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
noticing sounds (key touch sound and completion sound).
noticing sounds (key touch sound and completion sound).
6) Door Sensing Switch (Stop Switch)
A switch to “tell” the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, fan motor, turntable motor, grill
heater and light the oven lamp.
heater and light the oven lamp.
8) Indicator Circuit
Indicator element is a Fluorescent Display.
Basically, a Fluorescent Display is triode having a cath-
ode, a grid and an anode. Usually, the cathode of a
Fluorescent Display is directly heated and the filament
serves as cathode.
The Fluorescent Display has 6-digits, 13-segments are
used for displaying figures.
Basically, a Fluorescent Display is triode having a cath-
ode, a grid and an anode. Usually, the cathode of a
Fluorescent Display is directly heated and the filament
serves as cathode.
The Fluorescent Display has 6-digits, 13-segments are
used for displaying figures.
9) Absolute Humidity Sensor Circuit
The circuit detects absolute humidity of a food whith is
under cooking, to allow its automatic cooking.
under cooking, to allow its automatic cooking.
TOUCH CONTROL PANEL
18
R-4G75(W)M
R-4G75(B)M
R-4G75(B)M
DESCRIPTION OF LSI
LSI(IZA534DR)
The I/O signal of the LSI(IZA534DR) are detailed in the following table.
The I/O signal of the LSI(IZA534DR) are detailed in the following table.
Pin No.
Signal
I/O
Description
1
VCC
IN
Connected to GND.
2
VEE
IN
Anode (segment) of Fluorescent Display illumination voltage: -26V.
Vp voltage of power source circuit input.
Vp voltage of power source circuit input.
3
AVSS
IN
Reference voltage input terminal.
A reference voltage applied to the A/D converter in the LSI. The reference voltage is
generally maintaned at -5V.
A reference voltage applied to the A/D converter in the LSI. The reference voltage is
generally maintaned at -5V.
4
VREF
IN
Reference voltage input terminal.
A reference voltage applied to the A/D converter in the LSI. Connected to GND.(0V)
A reference voltage applied to the A/D converter in the LSI. Connected to GND.(0V)
5
P67
IN
Used for initial balancing of the bridge circuit (absolute humidity sensor). This input is
an analog input terminal from the AH sensor circuit, and connected to the A/D coverter
built into the LSI.
an analog input terminal from the AH sensor circuit, and connected to the A/D coverter
built into the LSI.
6
P66
IN
AH sensor input.
This input is an analog input terminal from the AH sensor circuit, and connected to the
A/D converter built into the LSI.
This input is an analog input terminal from the AH sensor circuit, and connected to the
A/D converter built into the LSI.
7
P65
IN
Terminal not used.
8-11
P64-P61
IN
Heating constant compensation terminal.
12
P60
IN
Input signal which communicates the door open/close information to LSI.
Door closed; “H” level signal(0V).
Door opened; “L” level signal(-5V).
Door closed; “H” level signal(0V).
Door opened; “L” level signal(-5V).
13
P55
OUT
Oven lamp driving signal. (Square Waveform : 50Hz).
To turn on and off the shut-off relay
(RY1). The square waveform voltage is
delivered to the relay (RY1) driving cir-
cuit and relays (RY2-RY3) control cir-
cuit.
To turn on and off the shut-off relay
(RY1). The square waveform voltage is
delivered to the relay (RY1) driving cir-
cuit and relays (RY2-RY3) control cir-
cuit.
14
P54
OUT
Terminal not used.
15
P53
OUT
Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay (RY2).
In High operation, the signals holds “L”
level during microwave cooking and “H”
level while not cooking. In other cooking
modes (M. HIGH, MED, M.LOW, LOW)
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 High operation, the signals holds “L”
level during microwave cooking and “H”
level while not cooking. In other cooking
modes (M. HIGH, MED, M.LOW, LOW)
the signal turns to “H” level and “L” level
in repetition according to the power level.
16
P52
OUT
Terminal not used.
17
P51
OUT
Grill heater driving signal.
To turn on and off the grill heater relay
(RY3). "L" level during grill or dual cook-
ing; "H" level otherwise.
To turn on and off the grill heater relay
(RY3). "L" level during grill or dual cook-
ing; "H" level otherwise.
18
P50
OUT
Terminal not used.
19
P47
OUT
Signal to sound buzzer.
A: key touch sound.
B: Completion sound.
A: key touch sound.
B: Completion sound.
20-24
P46-P42
OUT
Terminal not used.
25
P41
IN
Signal to synchronize LSI with commercial power source frequency.
This is basic timing for all real time processing of LSI.
This is basic timing for all real time processing of LSI.
26
P40
IN
Connected to GND.
During cooking
H
L
20 msec
ON
OFF
During
cooking
L
GND
H.
(Grill or dual)
A
B
0.12 sec.
2.4 sec.
20 msec
H : GND
L (-5V)
VARI-MODE
ON-TIME
OFF-TIME
HIGH
32sec.
0sec.
(100% power)
M.HIGH
24sec.
8sec.
(approx. 70% power)
MED
18sec.
14sec.
(approx. 50% power)
M.LOW
12sec.
20sec.
(approx. 30% power)
LOW
6sec.
26sec.
(approx. 10% power)
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