Sharp R-2398G Service Manual ▷ View online
15
R-2398
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
b) For a certain digit, brightness is low.
c) Only one indicator does not light.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
c) Only one indicator does not light.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
2-3 Other possible problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Cooking is not possible.
b) Cooking is not possible.
CARRY OUT 3D CHECKS.
If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable is
making good contact, verify that the door sensing switch (stop switch ) operates properly; that is the
contacts are closed when the door is closed and open when the door is open. If the door sensing switch
(stop switch ) is good, disconnect the flat ribbon cable that connects the key unit to the control unit and
make sure the door sensing switch is closed (either close the door or short the stop switch connector
). Use the key unit matrix indicated on the control panel schematic and place a jumper wire between
the pins that correspond to the STOP/CLEAR pad making momentary contact. If the control unit
responds by clearing with a beep, the key unit is faulty and must be replaced. If the control unit does
not respond, it is faulty and must be replaced. If a specific pad does not respond, the above method
may be used (after clearing the control unit ) to determine if the control unit or key pad is at fault.
If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable is
making good contact, verify that the door sensing switch (stop switch ) operates properly; that is the
contacts are closed when the door is closed and open when the door is open. If the door sensing switch
(stop switch ) is good, disconnect the flat ribbon cable that connects the key unit to the control unit and
make sure the door sensing switch is closed (either close the door or short the stop switch connector
). Use the key unit matrix indicated on the control panel schematic and place a jumper wire between
the pins that correspond to the STOP/CLEAR pad making momentary contact. If the control unit
responds by clearing with a beep, the key unit is faulty and must be replaced. If the control unit does
not respond, it is faulty and must be replaced. If a specific pad does not respond, the above method
may be used (after clearing the control unit ) to determine if the control unit or key pad is at fault.
CARRY OUT 4R CHECKS.
P
KEY UNIT TEST
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between Pin Nos. 5 and 7 of the connector (A) on the control
unit with an A.C. voltmeter. The meter should indicate 230~240 volts, if not check control unit circuity.
unit with an A.C. voltmeter. The meter should indicate 230~240 volts, if not check control unit circuity.
RY1, RY3 and RY4 Relay Test
These relays are operated by D.C. voltage.
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation.
These relays are operated by D.C. voltage.
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation.
DC. voltage indicated .............................Defective relay.
DC. voltage not indicated ....................... Check diode which is connected to the relay coil. If
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. 19.0V D.C.
Oven lamp, Blower motor and Stirrer motors
RY3
APPROX. 16.0V D.C.
High voltage transformer 1
RY4
APPROX. 18.0V D.C.
High voltage transformer 2
CARRY OUT 4R CHECKS.
Q
RELAY TEST
SET
3
4
5
6
7
8
9
0
2
CHECK
SIGNAL
START
STOP /
CLEAR
CLEAR
1
11
12
13
14
15
16
19
20
17
18
DOUBLE
QUANTITY
EXPRESS
DEFROST
DEFROST
SELECT
TIME
SELECT
POWER
G12
G11
G10
G 9
G 8
G 7
G 6
G 5
G 4
G 3
G 2
G 1
R
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING
BOARD(PWB) IS OPEN
BOARD(PWB) IS OPEN
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.
PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide given below
for repair.
16
R-2398
4) Clock Circuit
This is a circuit for controlling clock frequency required
for operating IC1.
for operating IC1.
5) IC1 (Main Processor)
This is a one-chip microcomputer, responsible for
controlling the entire control unit.
controlling the entire control unit.
6) IC2 (Memory Processor)
This is a memory IC, responsible for memory function.
7) Display Circuit
This is a circuit for driving display tubes by IC1 output.
8) Key Input Circuit
This is a circuit for transmitting key input information to
IC1.
IC1.
9) Sound-body Driving Circuit
This is a circuit for driving sound body by IC1 output.
10) Relay Driving Circuit
This is a circuit for driving output relay by IC1 output.
11) Stop Switch Circuit
This is a circuit for driving IC1 to detect door opening/
closing.
closing.
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
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) Control Unit
(2) Key Unit
(2) Key Unit
The principal functions of these units and the signals
communicated among them are explained below.
communicated among them are explained below.
1. Control Unit
Signal of key touch and oven function control are all
processed by one microcomputer.
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..
side of the low voltage (T1) transformer to voltages
required at each part by full wave rectifying circuit,
constant voltage circuit, etc..
2) ACL Circuit
This is an Auto-clear Circuit, i.e., a reset circuit, which
enables IC1 to be activated from initial state.
enables IC1 to be activated from initial state.
3) Power Synchronizing Signal Generating Circuit
This is a circuit for generating power synchronizing
signal by virtue of the secondary side output of trans-
former T1.
This signal is used for a basic frequency to time
processing and so on.
signal by virtue of the secondary side output of trans-
former T1.
This signal is used for a basic frequency to time
processing and so on.
(J29)
(VRS2)
VRS1
(J24)
(J23)
(9)
9(7)
5(3)
3(1)
RY1
D81
c
a
b
d
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
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 at
Check supply voltage and oven power cord.
POWER terminal of CPU connector (CN-A).
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 J24 and solder.
(CARRY OUT 3D CHECKS BEFORE REPAIR)
(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)
(CARRY OUT 3D CHECKS BEFORE REPAIR)
NOTE: *At the time of these repairs, make a visual
inspection of the varistor for burning dam-
age 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.
age 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.
17
R-2398
12) Exhaust Air Temperature Detecting Circuit
This is a circuit for transmitting output change of
thermistor (Oven thermistor (1)) to IC1.
thermistor (Oven thermistor (1)) to IC1.
13) High Voltage Monitoring Circuit.
This circuit detects problems in the magnetron / high
voltage circuit by sensing a variation in the current
flowing through the primary winding of the high voltage
transformer.
voltage circuit by sensing a variation in the current
flowing through the primary winding of the high voltage
transformer.
During heating, the primary current of the high voltage
transformers also flows through the primary winding
of the current transformers CT1 and CT2. This causes
a current to be induced in the secondary windings of
CT1/CT2 and results in an AC voltage which is
determined by R61/R62.
transformers also flows through the primary winding
of the current transformers CT1 and CT2. This causes
a current to be induced in the secondary windings of
CT1/CT2 and results in an AC voltage which is
determined by R61/R62.
This AC voltage is then half wave rectified by D61/D62
and smoothed (filtered) by C61/C62.
This AC voltage is the input to the IN3 and IN5 ports of
IC1, which determines if there is a magnetron / high
voltage problem.
and smoothed (filtered) by C61/C62.
This AC voltage is the input to the IN3 and IN5 ports of
IC1, which determines if there is a magnetron / high
voltage problem.
Figure T-1. High Voltage Monitoring Circuit
14) Magnetron Temperature Circuit.
(Detect Noload or Fan Lock)
This is a circuit for transmitting output change of
thermistor (Magnetron thermistor) to IC1.
This is a circuit for transmitting output change of
thermistor (Magnetron thermistor) to IC1.
15) Oven Cavity Temperature Detecting Circuit.
This is a circuit for transmitting output change of
thermistor (Oven thermistor (2)) to IC1.
thermistor (Oven thermistor (2)) to IC1.
2. Key Unit
The key unit is composed of a matrix circuit in which
when a key it touched, one of signals P11, P12, P15,
P16 and P17 generated by the LSI, is passed through
the key and returned to the LSI as one of signals R0-
-R3. This model has 20 Memory pads. When the oven
is shipped, Memory pad 1 to 10 are set as follows: fig.1.
when a key it touched, one of signals P11, P12, P15,
P16 and P17 generated by the LSI, is passed through
the key and returned to the LSI as one of signals R0-
-R3. This model has 20 Memory pads. When the oven
is shipped, Memory pad 1 to 10 are set as follows: fig.1.
Memory No.
Cook Time
Output Power
1
10 sec.
100%
2
20 sec.
100%
3
30 sec.
100%
4
45 sec.
100%
5
1 min.
100%
6
1 min.15 sec
100%
7
1 min.30 sec.
100%
8
2 min.
100%
9
2 min.30 sec.
100%
10
3 mins.
100%
(fig. 1)
This model has a double quantity pad. When the oven
is shipped, Magnification "1.8" is preset in the double
quantity pad. This model has an defrost pad. When the
oven is shipped, defrost is set as follows: fig.2.
is shipped, Magnification "1.8" is preset in the double
quantity pad. This model has an defrost pad. When the
oven is shipped, defrost is set as follows: fig.2.
1STAGE
2STAGE
3STAGE
POWER
40%
30%
20%
DEFROSTING TIME 0.2T+20sec. 0.13T+30sec. 0.67T-50sec.
(fig. 2)
NOTE :
"CHECK" indicator will flash at half of defrosting time.
"CHECK" indicator will flash at half of defrosting time.
HIGH VOLTAGE TRANSFORMER
HIGH VOLTAGE CIRCUIT
MAIN BODY SIDE
MAIN BODY SIDE
T/C SIDE
CT1 or CT2
RY3 or RY4
R61 or
R62
R62
R65 or
R66
R66
D61 or
D62
D62
R63 or
R64
R64
Vc
C61 or C62
IC1
IN3 or
IN5 PORT
IN3 or
IN5 PORT
D63 or
D64
D64
DESCRIPTION OF LSI
LSI(IZA646DR)
The I/O signal of the LSI(IZA646DR) is detailed in the following table.
The I/O signal of the LSI(IZA646DR) is detailed in the following table.
Pin No.
Signal
I/O
Description
1
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)
2
IN7
IN
Temperature measurement input: MAGNETRON THERMISTOR AND OVEN
THERMISTOR (2).
By inputting DC voltage corresponding to the temperature detected by the thermis-
tor, this input is converted into temperature by the A/D converter built into the LSI.
THERMISTOR (2).
By inputting DC voltage corresponding to the temperature detected by the thermis-
tor, this input is converted into temperature by the A/D converter built into the LSI.
3
IN6
IN
Temperature measurement input: OVEN THERMISTOR (1).
By inputting DC voltage corresponding to the temperature detected by the thermis-
tor, 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 thermis-
tor, this input is converted into temperature by the A/D converter built into the LSI.
4
IN5
IN
A/D input for troubleshooting Magnetron 1.
5
IN4
IN
Terminal to change functions according to the model.
Signal in accordance with the model in operation is applied to set up its function.
Signal in accordance with the model in operation is applied to set up its function.
6
IN3
IN
A/D input for troubleshooting Magnetron 2.
7
IN2
IN
Connected to GND.(0V)
8
IN1
IN
Terminal not used.
9
IN0
IN
Connected to VC.
10
P47
OUT
Terminal not used.
18
R-2398
Pin No.
Signal
I/O
Description
11
P46
OUT
Memory (EEPROM) clock output.
12
P45
IN/OUT
Memory (EEPROM) data input/output.
13-14
P44-P43
OUT
Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay. In 100% power level operation, "L" level during
cooking; "H" level otherwise. In other power level operation (90, 80, 70, 60, 50, 40,
30, 20, 10 or 0%), "H" and "L" level is repeated according to power level.
To turn on and off the cook relay. In 100% power level operation, "L" level during
cooking; "H" level otherwise. In other power level operation (90, 80, 70, 60, 50, 40,
30, 20, 10 or 0%), "H" and "L" level is repeated according to power level.
Power level
ON
OFF
Power level
ON
OFF
100%
48sec. 0sec.
40%
22sec.
26sec.
90%
44sec. 4sec.
30%
16sec.
32sec.
80%
40sec. 8sec.
20%
12sec.
36sec.
70%
36sec. 12sec.
10%
8sec.
40sec.
60%
32sec. 16sec.
0%
0sec.
48sec.
50%
26sec. 22sec.
15
P42
OUT
Power supply output at thermistor detecting circuit.
(Output -5V in cooking only, but apply high impedance to others to prevent thermistor
from electrolytic corrosion occurrence.)
(Output -5V in cooking only, but apply high impedance to others to prevent thermistor
from electrolytic corrosion occurrence.)
16
P41
OUT
Terminal not used.
17
P40
OUT
Oven lamp, Blower motor and Stirrer motors driving signal. (Square Waveform
: 50Hz)
To turn on and off the shut-off relay (RY1).
The Square waveform voltage is delivered to
the RY1 relay driving circuit and relays(RY3,
RY4, COOK RELAY) control circuit.
: 50Hz)
To turn on and off the shut-off relay (RY1).
The Square waveform voltage is delivered to
the RY1 relay driving circuit and relays(RY3,
RY4, COOK RELAY) control circuit.
18-22
P37-P33
OUT
Terminal not used.
23
P32
OUT
Signal to sound buzzer.
This signal is to control the 2.5kHz
continuous signal.
continuous signal.
A: key touch sound.
B: Guidance sound.
C: Completion sound.
24
P31
IN
Signal synchronized with commercial power source frequency.
This is basic timing for all time processing of LSI.
25
P30
OUT
Terminal not used.
26
CNVSS
IN
Connected to Vc.(-5V)
27
RESET
IN
Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is supplied. Temporarily
set to "L" level the moment power is supplied, 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 supplied. Temporarily
set to "L" level the moment power is supplied, at this time the LSI is reset. Thereafter
set at "H" level.
28
XIN
IN
Internal clock oscillation frequency setting input.
The internal clock frequency is set by inserting the ceramic filter oscillation circuit with
respect to XOUT terminal.
The internal clock frequency is set by inserting the ceramic filter oscillation circuit with
respect to XOUT terminal.
29
XOUT
OUT
Internal clock oscillation frequency control output.
Output to control oscillation input of XIN.
Output to control oscillation input of XIN.
30/31
XCIN/XCOUT
IN/OUT
Terminal not used.
32
VSS
IN
Power source voltage: -5V.
VC voltage of power source circuit input.
VC voltage of power source circuit input.
33
ø
OUT
Terminal not used.
34
R3
IN
Signal coming from touch key.
When either one of G-12 line keys on key matrix is touched, a corresponding signal
When either one of G-12 line keys on key matrix is touched, a corresponding signal
GND
-5V
48 sec.
OFF
ON
H
L
20 msec
During cooking
A
B
C
0.12 sec
2.4 sec
1.2 sec
1.2 sec
GND
-5V
T
200
µ
sec.
200
µ
sec.
H : GND
L (-5V)
20 msec
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