Sharp R-8740 (serv.man17) Service Manual ▷ View online
R-8740M - 1
SHARP CORPORATION
SERVICE MANUAL
®
In interests of user-safety the oven should be restored to its original
condition and only parts identical to those specified should be
used.
condition and only parts identical to those specified should be
used.
R-8740M
MODEL
MICROWAVE OVEN WITH
GRILL AND CONVECTION
S1111118740M/
TABLE OF CONTENTS
Page
CAUTION, MICROWAVE RADIATION .................................................................................................... 3
GENERAL INFORMATION ....................................................................................................................... 3
SERVICING .............................................................................................................................................. 4
PRODUCT SPECIFICATIONS ................................................................................................................. 5
APPEARANCE VIEW .............................................................................................................................. 6
OPERATION SEQUENCE ........................................................................................................................ 7
FUNCTION OF IMPORTANT COMPONENTS ....................................................................................... 9
TROUBLESHOOTING GUIDE ............................................................................................................... 12
TEST PROCEDURE .............................................................................................................................. 14
CONTROL PANEL ASSEMBLY ............................................................................................................ 21
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................... 28
MICROWAVE MEASUREMENT ........................................................................................................... 33
TEST DATA AT A GLANCE/WIRING/REWIRING .................................................................................. 34
SCHEMATIC DIAGRAMS ....................................................................................................................... 35
PICTORIAL DIAGRAM .......................................................................................................................... 39
CONTROL PANEL CIRCUIT DIAGRAM ................................................................................................ 40
PRINTED WIRING BOARD DIAGRAM .................................................................................................. 41
PARTS LIST ........................................................................................................................................... 42
EXPLODED DIAGRAM OF OVEN PARTS ............................................................................................ 45
CONTROL PANEL/DOOR PARTS ......................................................................................................... 46
MISCELLANEOUS/PACKING & ACCESSORIES .................................................................................. 47
GENERAL INFORMATION ....................................................................................................................... 3
SERVICING .............................................................................................................................................. 4
PRODUCT SPECIFICATIONS ................................................................................................................. 5
APPEARANCE VIEW .............................................................................................................................. 6
OPERATION SEQUENCE ........................................................................................................................ 7
FUNCTION OF IMPORTANT COMPONENTS ....................................................................................... 9
TROUBLESHOOTING GUIDE ............................................................................................................... 12
TEST PROCEDURE .............................................................................................................................. 14
CONTROL PANEL ASSEMBLY ............................................................................................................ 21
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................... 28
MICROWAVE MEASUREMENT ........................................................................................................... 33
TEST DATA AT A GLANCE/WIRING/REWIRING .................................................................................. 34
SCHEMATIC DIAGRAMS ....................................................................................................................... 35
PICTORIAL DIAGRAM .......................................................................................................................... 39
CONTROL PANEL CIRCUIT DIAGRAM ................................................................................................ 40
PRINTED WIRING BOARD DIAGRAM .................................................................................................. 41
PARTS LIST ........................................................................................................................................... 42
EXPLODED DIAGRAM OF OVEN PARTS ............................................................................................ 45
CONTROL PANEL/DOOR PARTS ......................................................................................................... 46
MISCELLANEOUS/PACKING & ACCESSORIES .................................................................................. 47
R-8740M
R-8740M - 2
REMEMBER TO CHECK 3D
1) Disconnect the supply.
2) Door opened, and wedged open.
3) Discharge high voltage capacitor.
2) Door opened, and wedged open.
3) Discharge high voltage capacitor.
WARNING: AGAINST THE CHARGE OF THE HIGH-
VOLTAGE CAPACITOR
The high-voltage capacitor remains charged about 60 sec-
onds after the oven has been switched off. Wait for 60
seconds and then short-circuit the connection of the high-
voltage capacitor (that is, of the connecting lead of the high-
voltage rectifier) against the chassis with the use of an
insulated screwdriver.
onds after the oven has been switched off. Wait for 60
seconds and then short-circuit the connection of the high-
voltage capacitor (that is, of the connecting lead of the high-
voltage rectifier) against the chassis with the use of an
insulated screwdriver.
Sharp recommend that wherever possible fault-finding is
carried out with the supply disconnected. It may in, some
cases, be necessary to connect the supply after the outer
case has been removed, in this event carry out 3D checks and
then disconnect the leads to the primary of the High voltage
transformer. Ensure that these leads remain isolated from
other components and the oven chassis. (Use insulation tape
if necessary.) When the testing is completed carry out 3D
checks and reconnect the leads to the primary of the High
voltage transformer.
carried out with the supply disconnected. It may in, some
cases, be necessary to connect the supply after the outer
case has been removed, in this event carry out 3D checks and
then disconnect the leads to the primary of the High voltage
transformer. Ensure that these leads remain isolated from
other components and the oven chassis. (Use insulation tape
if necessary.) When the testing is completed carry out 3D
checks and reconnect the leads to the primary of the High
voltage transformer.
SERVICING
WARNING TO SERVICE PERSONNEL
Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts will
result in electrocution.
High voltage capacitor, High voltage transformer, Magnetron, High voltage rectifier assembly, High voltage wires.
result in electrocution.
High voltage capacitor, High voltage transformer, Magnetron, High voltage rectifier assembly, High voltage wires.
REMEMBER TO CHECK 4R
1) Reconnect all leads removed from components during
testing.
2) Replace the outer case (cabinet).
3) Reconnect the supply.
4) Run the oven. Check all functions.
testing.
2) Replace the outer case (cabinet).
3) Reconnect the supply.
4) Run the oven. Check all functions.
Microwave ovens should not be run empty. To test for the
presence of microwave energy within a cavity, place a cup of
cold water on the oven turntable, close the door and set the
power to HIGH and set the microwave timer for two (2) minutes.
When the two minutes has elapsed (timer at zero) carefully
check that the water is now hot. If the water remains cold carry
out 3D checks and re-examine the connections to the compo-
nent being tested.
presence of microwave energy within a cavity, place a cup of
cold water on the oven turntable, close the door and set the
power to HIGH and set the microwave timer for two (2) minutes.
When the two minutes has elapsed (timer at zero) carefully
check that the water is now hot. If the water remains cold carry
out 3D checks and re-examine the connections to the compo-
nent being tested.
When all service work is completed, and the oven is fully
assembled, the microwave power output should be checked and
a microwave leakage test should be carried out.
assembled, the microwave power output should be checked and
a microwave leakage test should be carried out.
R-8740M - 3
®
GRILL AND CONVECTION MICROWAVE OVEN
R-8740M
GENERAL IMPORTANT INFORMATION
This Manual has been prepared to provide Sharp Corp. Service engineers with Operation and Service Information.
It is recommended that service engineers carefully study the entire text of this manual, so they will be qualified to
render satisfactory customer service.
SERVICE MANUAL
WARNING
Never operate the oven until the following points are ensured.
(A) The door is tightly closed.
(B) The door and oven hinges are not defective.
(C) The door packing is not damaged.
(D) The door is not deformed or warped.
(E) There is not any other visible damage with the oven.
(A) The door is tightly closed.
(B) The door and oven hinges are not defective.
(C) The door packing is not damaged.
(D) The door is not deformed or warped.
(E) There is not any other visible damage with the oven.
Servicing and repair work must be carried out only by trained
Service Engineers.
Service Engineers.
All the parts marked ”*” on parts list are used at voltages more
than 250V.
than 250V.
Removal of the outer wrap gives access to potentials above
250V.
250V.
All the parts marked "∆" on the parts list may cause undue
microwave exposure, by themselves, or when they are dam-
aged, loosened or removed.
microwave exposure, by themselves, or when they are dam-
aged, loosened or removed.
SHARP CORPORATION
OSAKA, JAPAN
WARNING
MICROWAVE RADIATION
Personnel should not be exposed to the microwave energy
which may radiate from the magnetron or other microwave
generating devices if it is improperly used or connected. All
input and output microwave connections, waveguides, flanges
and gaskets must be secured. Never operate the device
without a microwave energy absorbing load attached. Never
look into an open waveguide or antenna while the device is
energized.
which may radiate from the magnetron or other microwave
generating devices if it is improperly used or connected. All
input and output microwave connections, waveguides, flanges
and gaskets must be secured. Never operate the device
without a microwave energy absorbing load attached. Never
look into an open waveguide or antenna while the device is
energized.
R-8740M - 4
SERVICING
CAUTION
MICROWAVE RADIATION
Service engineers should not be exposed to the
microwave energy which may radiate from the magnetron
or other microwave generating devices if it is improperly
used or connected. All input and output microwave
connections, waveguides, flanges and gaskets must be
secured. Never operate the device without a microwave
energy absorbing load attached. Never look into an open
waveguide or antenna while the device is energized.
microwave energy which may radiate from the magnetron
or other microwave generating devices if it is improperly
used or connected. All input and output microwave
connections, waveguides, flanges and gaskets must be
secured. Never operate the device without a microwave
energy absorbing load attached. Never look into an open
waveguide or antenna while the device is energized.
WARNING
THIS APPLIANCE MUST BE EARTHED
. THE WIRES IN THIS MAINS LEAD ARE COLOURED IN
ACCORDANCE WITH THE FOLLOWING CODE:
GREEN-AND-YELLOW : EARTH BLUE : NEUTRAL BROWN : LIVE
GREEN-AND-YELLOW : EARTH BLUE : NEUTRAL BROWN : LIVE
WARNING
Servicing and repair work must be carried out only by
trained service engineers.
All the parts marked "*" on parts list are used at
voltages more than 250V.
Removal of the outer wrap gives access to potentials
above 250V.
All the parts marked "∆" on parts list may cause undue
microwave exposure, by themselves, or when they
are damaged, loosened or removed.
trained service engineers.
All the parts marked "*" on parts list are used at
voltages more than 250V.
Removal of the outer wrap gives access to potentials
above 250V.
All the parts marked "∆" on parts list may cause undue
microwave exposure, by themselves, or when they
are damaged, loosened or removed.
CAUTION/WARNING
REMEMBER TO CHECK 3D
1) Disconnect the supply.
2) Door opened, and wedged open.
3) Discharge high voltage capacitor.
2) Door opened, and wedged open.
3) Discharge high voltage capacitor.
WARNING: AGAINST THE CHARGE OF THE HIGH-
VOLTAGE CAPACITOR
The high-voltage capacitor remains charged about 60 sec-
onds after the oven has been switched off. Wait for 60
seconds and then short-circuit the connection of the high-
voltage capacitor (that is, of the connecting lead of the high-
voltage rectifier) against the chassis with the use of an
insulated screwdriver.
onds after the oven has been switched off. Wait for 60
seconds and then short-circuit the connection of the high-
voltage capacitor (that is, of the connecting lead of the high-
voltage rectifier) against the chassis with the use of an
insulated screwdriver.
Sharp recommend that wherever possible fault-finding is
carried out with the supply disconnected. It may in, some
cases, be necessary to connect the supply after the outer
case has been removed, in this event carry out 3D checks and
then disconnect the leads to the primary of the High voltage
transformer. Ensure that these leads remain isolated from
other components and the oven chassis. (Use insulation tape
if necessary.) When the testing is completed carry out 3D
checks and reconnect the leads to the primary of the High
voltage transformer.
carried out with the supply disconnected. It may in, some
cases, be necessary to connect the supply after the outer
case has been removed, in this event carry out 3D checks and
then disconnect the leads to the primary of the High voltage
transformer. Ensure that these leads remain isolated from
other components and the oven chassis. (Use insulation tape
if necessary.) When the testing is completed carry out 3D
checks and reconnect the leads to the primary of the High
voltage transformer.
WARNING TO SERVICE PERSONNEL
Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts will
result in electrocution.
High voltage capacitor, High voltage transformer, Magnetron, High voltage rectifier assembly, High voltage wires.
result in electrocution.
High voltage capacitor, High voltage transformer, Magnetron, High voltage rectifier assembly, High voltage wires.
REMEMBER TO CHECK 4R
1) Reconnect all leads removed from components during
testing.
2) Replace the outer case (cabinet).
3) Reconnect the supply.
4) Run the oven. Check all functions.
testing.
2) Replace the outer case (cabinet).
3) Reconnect the supply.
4) Run the oven. Check all functions.
Microwave ovens should not be run empty. To test for the
presence of microwave energy within a cavity, place a cup of
cold water on the oven turntable, close the door and set the
power to HIGH and set the microwave timer for two (2) minutes.
When the two minutes has elapsed (timer at zero) carefully
check that the water is now hot. If the water remains cold carry
out 3D checks and re-examine the connections to the compo-
nent being tested.
presence of microwave energy within a cavity, place a cup of
cold water on the oven turntable, close the door and set the
power to HIGH and set the microwave timer for two (2) minutes.
When the two minutes has elapsed (timer at zero) carefully
check that the water is now hot. If the water remains cold carry
out 3D checks and re-examine the connections to the compo-
nent being tested.
When all service work is completed, and the oven is fully
assembled, the microwave power output should be checked and
a microwave leakage test should be carried out.
assembled, the microwave power output should be checked and
a microwave leakage test should be carried out.
