Sharp R-21ATP Service Manual ▷ View online
R-21ATP
11
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
K
TOUCH CONTROL PANEL ASSEMBLY TEST
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore,
unlike conventional microwave ovens, proper maintenance can not be performed with only a voltmeter
and ohmmeter.
In this service manual, the touch control panel assembly is divided into two units, Control Unit and Key
Unit and troubleshooting by replacement is described according to the symptoms indicated.
1. Key Unit Note : Check key unit ribbon connection before replacement.
unlike conventional microwave ovens, proper maintenance can not be performed with only a voltmeter
and ohmmeter.
In this service manual, the touch control panel assembly is divided into two units, Control Unit and Key
Unit and troubleshooting by replacement is described according to the symptoms indicated.
1. Key Unit Note : Check key unit ribbon connection before replacement.
The following symptoms indicate a defective key unit. Replace the key unit.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
2. Control Panel
The following symptoms indicate a defective control unit. Before replacing the control unit.
perform the key unit test (Procedure L) to determine if control unit is faulty.
perform the key unit test (Procedure L) to determine if control unit is faulty.
2-1 In connection with pads
a) When touching the pads, a certain group of pads do not produce a signal.
b) When touching the pads, no pads produce a signal.
b) When touching the pads, no pads produce a signal.
2-2 In connection with indicators
a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light up.
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.
b) At a certain digit, brightness is low.
c) Only one indicator does not light up.
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 troubles caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
b) Clock does not operate properly.
c) Cooking is not possible.
If the high voltage fuse is blown, there could be a short in the high voltage rectifier or the magnetron.
Check them and replace the defective parts and the high voltage fuse.
Check them and replace the defective parts and the high voltage fuse.
CARRY OUT 4R CHECKS.
CAUTION:
Only replace high voltage fuse with the correct value replacement.
If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable is
marking good contact, verify that the 2nd. interlock relay control switch operates properly; that is the
contacts are closed when the door is closed and open when the door is open. If the 2nd. interlock relay
control switch is good, disconnect the flat ribbon cable that connects the key unit to the control unit and
make sure the 2nd. interlock relay control switch is closed (either close the door or short the d2nd.
interlock relay control switch connecter). 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 marking
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 a 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.
marking good contact, verify that the 2nd. interlock relay control switch operates properly; that is the
contacts are closed when the door is closed and open when the door is open. If the 2nd. interlock relay
control switch is good, disconnect the flat ribbon cable that connects the key unit to the control unit and
make sure the 2nd. interlock relay control switch is closed (either close the door or short the d2nd.
interlock relay control switch connecter). 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 marking
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 a 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.
L
KEY UNIT TEST
CARRY OUT 4R CHECKS.
5
6
3
4
1
11
13
15
19
12
14
16
20
17
18
2
7
8
9
0
SELECT
TIME
SELECT
POWER
STOP/
CLEAR
START
SET
CHECK
SIGNAL
DOUBLE
QUANTITY
EXPRESS
DEFROST
G12
G11
G10
G 9
G 1
G 2
G 3
G 4
G 5
G 6
G 7
G 8
12
R-21ATP
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
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 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 J1 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 damage and examine the
transformer with tester for the pres-
ence of layer short circuit (check pri-
mary coil resistance).
If any abnormal condition is detected,
replace the defective parts.
burning damage and examine the
transformer with tester for the pres-
ence of layer short circuit (check pri-
mary coil resistance).
If any abnormal condition is detected,
replace the defective parts.
CARRY OUT 4R CHECKS.
N
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(PWB) IS OPEN
(PWB) IS OPEN
M
RELAY TEST
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between Pin Nos. 3 and 7 of the 3 pin connector (A) on the
control unit with an A.C. voltmeter.
The meter should indicate 230-240 volts, if not check oven circuit.
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.
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 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
RY2
Approx. 18.0V D.C.
High voltage transformer
RY3
Approx. 18.0V D.C.
Oven lamp / Antenna motor / Fan motor
CARRY OUT 4R CHECKS.
(17)
a
b
c
d
(CT1)
(J1)
(J2)
(TB1)
12
P
VRS1
(VRS2)
POWER
7
R-21ATP
13
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) Reset Circuit
This is a reset circuit, which enables IC1 to be acti-
vated from initial state.
vated from initial state.
3) Power SYNC Signal Generating Circuit
This is a circuit for generating power SYNC 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.
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 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) IC3
This is a IC for driving light emitting diode.
8) Display Circuit
This is a circuit for driving light emitting diode by IC1
output.
output.
9) Key Input Circuit
This is a circuit for transmitting key input information to
IC1.
IC1.
10) Sound-body Driving Circuit
This is a circuit for driving sound body by IC1 output.
CONTROL PANEL ASSEMBLY
OUTLINE OF CONTROL PANEL
11) Relay Driving Circuit
This is a circuit for driving output relay by IC1 output.
12) 2nd. Interlock Relay Control switch Circuit
This is a circuit for driving IC1 to detect door opening/
closing.
closing.
2. Key Unit
The key unit is composed of a matrix circuit in which
when a key it touched, one of signals P30--P34 gen-
erated by the LSI, is passed through the key and
returned to the LSI as one of signals P24--P27.
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 P30--P34 gen-
erated by the LSI, is passed through the key and
returned to the LSI as one of signals P24--P27.
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%
0
3 min.
100%
(fig. 1)
This model has a double quantity pad. When the oven
is shipped, Magnification "1.7" is preset in the double
quantity pad.
This model has an express defrost pad. When the
oven is shipped, express defrost is set as follows: fig.2.
is shipped, Magnification "1.7" is preset in the double
quantity pad.
This model has an express defrost pad. When the
oven is shipped, express defrost is set as follows: fig.2.
1 STAGE
2 STAGE
3 STAGE
FORMULA
P = 0.2T
P = 0.15T
P = 0.65T
POWER
60 %
40 %
20 %
T : Total cooling time
(fig. 2)
When 1/2 total cooking time is passed, the signal
will sound and "CHECK" indicator will flash
14
R-21ATP
1
VCC
IN
Power source voltage: +5V.
VC voltage of power source circuit input.
VC voltage of power source circuit input.
2/3
VEE/AVSS
IN
Connected to GND
4
VREF
IN
Connected to VC. (+5V)
5-6
AN7-AN6
IN
Terminal not used.
7-8
AN5-AN4
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.
9-10
AN3-AN2
IN
Terminal not used.
11
AN1
IN
Input signal which communicates the door open/close information to LSI.
Door closed; "L" level signal (0V).
Door opened; "H" level signal (+5V).
Door closed; "L" level signal (0V).
Door opened; "H" level signal (+5V).
12
AN0
IN
Terminal not used.
13
P55
OUT
Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay. In 100% power level operation, "H" level during
cooking; "L" 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, "H" level during
cooking; "L" 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%
32sec.
0sec.
40%
16sec.
16sec.
90%
30sec.
2sec.
30%
12sec.
20sec.
80%
26sec.
6sec.
20%
8sec.
24sec.
70%
24sec.
8sec.
10%
6sec.
26sec.
60%
22sec. 10sec.
0%
0sec.
32sec.
50%
18sec. 14sec.
14-15
P54-P53
OUT
Terminal not use
µ
d.
16-18
P52-P50
IN
Terminal not used.
19
P47
OUT
Signal to sound buzzer.
This signal is to control the 2.5kHz
continuous signal through IC3.
A: key touch sound.
B: Guidance sound.
C: Completion sound.
This signal is to control the 2.5kHz
continuous signal through IC3.
A: key touch sound.
B: Guidance sound.
C: Completion sound.
20
P46
OUT
Oven lamp, Fan motor and Antenna motor driving signal. (Square
Waveform : 50Hz)
To turn on and off the shut-off relay (RY3).
The Square waveform voltage is delivered
to the RY3 driving circuit and relays(RY2,
COOK RELAY) control circuit.
Waveform : 50Hz)
To turn on and off the shut-off relay (RY3).
The Square waveform voltage is delivered
to the RY3 driving circuit and relays(RY2,
COOK RELAY) control circuit.
21
P45
OUT
Digit selection signal.
The relation between digit signal and
digit are as follows:
The relation between digit signal and
digit are as follows:
Digit signal
Digit
P42 ....................... 1st.
P43 ...................... 2nd.
P44 ...................... 3rd.
P45 ....................... 4th.
P43 ...................... 2nd.
P44 ...................... 3rd.
P45 ....................... 4th.
Normally, one pulse is output in every ß period, and input to the grid of the light-
emitting diode.
emitting diode.
22-24
P44-P42
OUT
Digit selection signal.
Signal similar to P45.
Signal similar to P45.
+5V
GND
32 sec.
ON
OFF
A
0.12 sec
2.4 sec
1.2 sec
+5V
GND
T
200
µ
sec.
200
µ
sec.
1.2 sec
B
+5V
GND
C
+5V
GND
H
L
20 msec
During cooking
H
L
+5V
ß(50Hz)
P42
P43
P44
P45
GND
DESCRIPTION OF LSI
LSI
The I/O signal of the LSI are detailed in the following table.
The I/O signal of the LSI are detailed in the following table.
Pin No.
Signal
I/O
Description
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