DOWNLOAD Sharp R-8740 (serv.man6) Service Manual ↓ Size: 462.12 KB | Pages: 3 in PDF or view online for FREE

Model
R-8740 (serv.man6)
Pages
3 Few pages! See other manuals at the bottom of the first or last page.
Size
462.12 KB
Type
PDF
Document
Service Manual
Brand
Device
Home Appliance / Microwave Oven / Function of important components
File
r-8740-sm6.pdf
Date

Sharp R-8740 (serv.man6) Service Manual ▷ View online

R-8740M  - 11
SENSING FIRE OPERATION
The oven will stop its operation when there is a fire in the
oven cavity in microwave cooking condition.
LSI measures the voltage across the temperature measure-
ment circuit intermittently within a 32-second time base after
since the oven is started in microwave cooking condition.
The oven will stop its operation when the difference of the
voltages is more than 0.69 volts in microwave cooking
condition.
1. Within a 32-second base, first the thermistor is energized
for 3 seconds.  After 2 seconds since the thermistor is
energized, the voltage across the temperature
measurement circuit is measured. And after 21 seconds
since the thermistor is cut off, the convection motor
operates for 10 seconds.
2. The oven carries out the procedure above again. If the
second voltage is 0.69V higher than the first voltage, LSI
judges it is a fire in the oven cavity and stops the oven.
3. When sensor cooking, the sensing fire operation is not
carried out until the oven senses the steam from food.
Because food cannot be cooked well by rotating the
convection fan at that time. After sensing the steam, the
sensing fire operation is started.
4. When LSI judges it is fire in the oven cavity, LSI will switch
off the relays to the power transformer, fan motor and
convection motor and LSI stops counting down. And then
the damper is closed so that the fresh air does not come
into the oven cavity.
.
.
FUNCTION OF IMPORTANT COMPONENTS
THERMISTOR
SENSING
VOLTAGE
ON
OFF
ON
OFF
0
20
64 (sec.)
3 sec.
2
30 32
10 SEC.
Sensing the voltage across temperature measurement circuit.
ON
OFF
CONVECTION
MOTOR
R-8740M  - 11
SENSING FIRE OPERATION
The oven will stop its operation when there is a fire in the
oven cavity in microwave cooking condition.
LSI measures the voltage across the temperature measure-
ment circuit intermittently within a 32-second time base after
since the oven is started in microwave cooking condition.
The oven will stop its operation when the difference of the
voltages is more than 0.69 volts in microwave cooking
condition.
1. Within a 32-second base, first the thermistor is energized
for 3 seconds.  After 2 seconds since the thermistor is
energized, the voltage across the temperature
measurement circuit is measured. And after 21 seconds
since the thermistor is cut off, the convection motor
operates for 10 seconds.
2. The oven carries out the procedure above again. If the
second voltage is 0.69V higher than the first voltage, LSI
judges it is a fire in the oven cavity and stops the oven.
3. When sensor cooking, the sensing fire operation is not
carried out until the oven senses the steam from food.
Because food cannot be cooked well by rotating the
convection fan at that time. After sensing the steam, the
sensing fire operation is started.
4. When LSI judges it is fire in the oven cavity, LSI will switch
off the relays to the power transformer, fan motor and
convection motor and LSI stops counting down. And then
the damper is closed so that the fresh air does not come
into the oven cavity.
.
.
FUNCTION OF IMPORTANT COMPONENTS
THERMISTOR
SENSING
VOLTAGE
ON
OFF
ON
OFF
0
20
64 (sec.)
3 sec.
2
30 32
10 SEC.
Sensing the voltage across temperature measurement circuit.
ON
OFF
CONVECTION
MOTOR
R-8740M  - 11
SENSING FIRE OPERATION
The oven will stop its operation when there is a fire in the
oven cavity in microwave cooking condition.
LSI measures the voltage across the temperature measure-
ment circuit intermittently within a 32-second time base after
since the oven is started in microwave cooking condition.
The oven will stop its operation when the difference of the
voltages is more than 0.69 volts in microwave cooking
condition.
1. Within a 32-second base, first the thermistor is energized
for 3 seconds.  After 2 seconds since the thermistor is
energized, the voltage across the temperature
measurement circuit is measured. And after 21 seconds
since the thermistor is cut off, the convection motor
operates for 10 seconds.
2. The oven carries out the procedure above again. If the
second voltage is 0.69V higher than the first voltage, LSI
judges it is a fire in the oven cavity and stops the oven.
3. When sensor cooking, the sensing fire operation is not
carried out until the oven senses the steam from food.
Because food cannot be cooked well by rotating the
convection fan at that time. After sensing the steam, the
sensing fire operation is started.
4. When LSI judges it is fire in the oven cavity, LSI will switch
off the relays to the power transformer, fan motor and
convection motor and LSI stops counting down. And then
the damper is closed so that the fresh air does not come
into the oven cavity.
.
.
FUNCTION OF IMPORTANT COMPONENTS
THERMISTOR
SENSING
VOLTAGE
ON
OFF
ON
OFF
0
20
64 (sec.)
3 sec.
2
30 32
10 SEC.
Sensing the voltage across temperature measurement circuit.
ON
OFF
CONVECTION
MOTOR
R-8740M  - 11
SENSING FIRE OPERATION
The oven will stop its operation when there is a fire in the
oven cavity in microwave cooking condition.
LSI measures the voltage across the temperature measure-
ment circuit intermittently within a 32-second time base after
since the oven is started in microwave cooking condition.
The oven will stop its operation when the difference of the
voltages is more than 0.69 volts in microwave cooking
condition.
1. Within a 32-second base, first the thermistor is energized
for 3 seconds.  After 2 seconds since the thermistor is
energized, the voltage across the temperature
measurement circuit is measured. And after 21 seconds
since the thermistor is cut off, the convection motor
operates for 10 seconds.
2. The oven carries out the procedure above again. If the
second voltage is 0.69V higher than the first voltage, LSI
judges it is a fire in the oven cavity and stops the oven.
3. When sensor cooking, the sensing fire operation is not
carried out until the oven senses the steam from food.
Because food cannot be cooked well by rotating the
convection fan at that time. After sensing the steam, the
sensing fire operation is started.
4. When LSI judges it is fire in the oven cavity, LSI will switch
off the relays to the power transformer, fan motor and
convection motor and LSI stops counting down. And then
the damper is closed so that the fresh air does not come
into the oven cavity.
.
.
FUNCTION OF IMPORTANT COMPONENTS
THERMISTOR
SENSING
VOLTAGE
ON
OFF
ON
OFF
0
20
64 (sec.)
3 sec.
2
30 32
10 SEC.
Sensing the voltage across temperature measurement circuit.
ON
OFF
CONVECTION
MOTOR
Display

Sharp R-8740 (serv.man6) Service Manual ▷ Download

  • DOWNLOAD Sharp R-8740 (serv.man6) Service Manual ↓ Size: 462.12 KB | Pages: 3 in PDF or view online for FREE
  • Here you can View online or download the Service Manual for the Sharp R-8740 (serv.man6) in PDF for free, which will help you to disassemble, recover, fix and repair Sharp R-8740 (serv.man6) Microwave Oven. Information contained in Sharp R-8740 (serv.man6) Service Manual (repair manual) includes:
  • Disassembly, troubleshooting, maintenance, adjustment, installation and setup instructions.
  • Schematics, Circuit, Wiring and Block diagrams.
  • Printed wiring boards (PWB) and printed circuit boards (PCB).
  • Exploded View and Parts List.