Sharp R-2397 - Manual (Page 8)

6
R-2397
MAGNETRON THERMISTOR
The air temperature around the lower magnetron is
detected through the resistance of the thermistor.
If the temperature is high, the control panel will display
"EE17" and the oven will stop to protect the lower
magnetron against overheat.
If the thermistor is open, the control panel will display
"EE16" and the oven will stop.
MAGNETRON THERMAL CUT-OUTS 145˚
These thermal cut-outs protect the magnetrons against
overheat. If their temperature go up higher than 145˚C
because the blower motor is interrupted, the ventilation
openings are blocked, the thermal cut-outs will open and
the line voltage to the high voltage transformer will be cut
off and the operations of the magnetrons will be stopped.
The defective thermal cut-out must be replaced with new
rated one.
BLOWER MOTOR THERMAL CUT-OUT 115˚C
This thermal cut-out protect the blower motor against
overheat. If its temperature goes up higher than 115˚C
because the blower motor is locked or the ventilation
openings are blocked, the contacts of the thermal cut-out
will open and the line voltage to the control unit will be cut
off and the operation of the oven will be stopped. The
defective thermal cut-out must be replaced with new rated
one.
OVEN THERMAL CUT-OUT 115˚C
This thermal cut-out protects the oven against overheat. If
the temperature goes up higher than 115˚C because the
food catches fire, the contacts of
thermal cut-out will open
and the line voltage to the control unit will be cut off and the
operation of the oven will be stopped. The defective
thermal
cut-out must be replaced with a new rated one.
BLOWER MOTOR
The blower motor drives a blade which draws external
cool air. This cool air is directed through the air vanes
surrounding the magnetrons and cools the magnetrons.
This air is channelled through the oven cavity to remove
steam and vapours given off from the heating foods. It is
then exhausted through the exhausting air vents at the
oven cavity.
STIRRER MOTOR
The stirrer motor drives a stirrer antenna to stir the
microwave radiation from the waveguide.
FUSE F6.3A 250V
1. If the wire harness or electrical components are short-
circuited, this fuse blows to prevent an electric shock
or fire hazard.
2. The fuse also blows when 1st latch switch remains
closed with the oven door open and when the monitor
switch closes.
ASYMMETRIC RECTIFIER
The asymmetric rectifier is solid state device that pre-
vents current flow is both directions. And it prevents the
temperature rise of the high voltage transformer by
blowing the weak point when the high voltage rectifier is
shorted.
A B
C
D2 D1
ASYMMETRIC
RECTIFIER
HIGH VOLTAGE RECTIFIER
The rated peak reverse voltage of D1 of the asymmetric
rectifier is 6 KV The rated peak reverse voltage of D2 of
the asymmetric rectifier is 1.7 KV. D1 and D2 of the
asymmetric rectifier or high voltage rectifier are shorted
when the each peak reverse voltage goes beyond the
each rated peak reverse voltage.
1. The high voltage rectifier is shorted by some fault
when microwave cooking.
2. The peak reverse voltage of D2 of the rectifier goes
beyond the rated peak reverse voltage 1.7 KV in the
voltage doubler circuit.
3. D2 of the rectifier is shorted.
4. The large electric currents flow through the high
voltage winding of the high voltage transformer.
5. The large electric currents flow through the primary
winding of the high voltage transformer.
6. The weak point blows by the large electric currents.
7. The power supplying to the high voltage transformer
is cut off.
EXHAUST THERMISTOR
The thermistor is a negative temperature coefficient type.
The temperature in the exhaust duct is detected through
the resistance of the thermistor.
If the temperature is high, the control panel will display
“EE7” and the oven will stop to avoid overheating and
catching fire.
If the thermistor is open, the control panel will display
"EE6" and the oven will stop.
INTAKE THERMISTOR
This thermistor detects ambient air temperature.