Sharp R-8740 (serv.man8) Service Manual ▷ View online
R-8740M - 20
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)
4
Pattern at "a" and "b" are broken.
*Insert the coil RCILF2003YAZZ between "c" and "d".
(CARRY OUT 3D CHECKS BEFORE REPAIR)
Q
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(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 3D CHECKS
Q20
a
b
c
d
RY5
FM
(J1)
B
PWR
CN - A
VRS1
T1
P
4
1
RY6
AC
D25
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
R
KEY UNIT TEST
If the display fails to clear when the STOP pad is depressed, first verify the flat ribbon cable is
marking 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 door sensing 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 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 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 door sensing 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 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.
CARRY OUT 4R CHECKS.
R-8740M
4
5
2
5
7
9
0
4
6
8
1
3
6
7
8
9
10
11
12
3
2
1
TIME
REDUCE
MEMORY
MANUAL
MICROWAVE
CONVECTION
BOTTOM
GRILL
SOUND
TOP
GRILL
STOP
START
R-8740M - 20
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)
4
Pattern at "a" and "b" are broken.
*Insert the coil RCILF2003YAZZ between "c" and "d".
(CARRY OUT 3D CHECKS BEFORE REPAIR)
Q
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(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 3D CHECKS
Q20
a
b
c
d
RY5
FM
(J1)
B
PWR
CN - A
VRS1
T1
P
4
1
RY6
AC
D25
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
R
KEY UNIT TEST
If the display fails to clear when the STOP pad is depressed, first verify the flat ribbon cable is
marking 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 door sensing 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 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 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 door sensing 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 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.
CARRY OUT 4R CHECKS.
R-8740M
4
5
2
5
7
9
0
4
6
8
1
3
6
7
8
9
10
11
12
3
2
1
TIME
REDUCE
MEMORY
MANUAL
MICROWAVE
CONVECTION
BOTTOM
GRILL
SOUND
TOP
GRILL
STOP
START
R-8740M - 20
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)
4
Pattern at "a" and "b" are broken.
*Insert the coil RCILF2003YAZZ between "c" and "d".
(CARRY OUT 3D CHECKS BEFORE REPAIR)
Q
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(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 3D CHECKS
Q20
a
b
c
d
RY5
FM
(J1)
B
PWR
CN - A
VRS1
T1
P
4
1
RY6
AC
D25
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
R
KEY UNIT TEST
If the display fails to clear when the STOP pad is depressed, first verify the flat ribbon cable is
marking 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 door sensing 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 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 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 door sensing 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 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.
CARRY OUT 4R CHECKS.
R-8740M
4
5
2
5
7
9
0
4
6
8
1
3
6
7
8
9
10
11
12
3
2
1
TIME
REDUCE
MEMORY
MANUAL
MICROWAVE
CONVECTION
BOTTOM
GRILL
SOUND
TOP
GRILL
STOP
START
R-8740M - 20
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)
4
Pattern at "a" and "b" are broken.
*Insert the coil RCILF2003YAZZ between "c" and "d".
(CARRY OUT 3D CHECKS BEFORE REPAIR)
Q
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(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 3D CHECKS
Q20
a
b
c
d
RY5
FM
(J1)
B
PWR
CN - A
VRS1
T1
P
4
1
RY6
AC
D25
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
R
KEY UNIT TEST
If the display fails to clear when the STOP pad is depressed, first verify the flat ribbon cable is
marking 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 door sensing 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 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 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 door sensing 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 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.
CARRY OUT 4R CHECKS.
R-8740M
4
5
2
5
7
9
0
4
6
8
1
3
6
7
8
9
10
11
12
3
2
1
TIME
REDUCE
MEMORY
MANUAL
MICROWAVE
CONVECTION
BOTTOM
GRILL
SOUND
TOP
GRILL
STOP
START
Display
