Sharp R-380A, Service Manual, Page: 7 / 40

R-380A
5
An example of how sensor works:
1. Potatoes at room temperature.
Vapor is emitted very slowly.
2. Heat potatoes. Moisture and
humidity is emitted rapidly.
You can smell the aroma as it
cooks.
3. Sensor detects moisture and
humidity and calculates
cooking time and variable
power.
Cooking Sequence.
1. Touch each SENSOR COOK or SENSOR INSTANT
REHEAT function pad to operating the sensor cooking.
NOTE: The oven should not be operated on SENSOR
COOK or SENSOR INSTANT REHEAT
immediately after plugging in the unit. Wait five
minutes before cooking on SENSOR COOK or
SENSOR INSTANT REHEAT.
2. The coil of shut-off relay (RY-1) is energized, the
turntable motor, oven lamp and cooling fan motor are
turned on, but the power transformer is not turned on.
3. After about 16 seconds, the cook relay (RY-2) is
energized. The power transformer is turned on,
microwave energy is produced and first stage is started.
The 16 seconds is the cooling time required to remove
any vapor from the oven cavity and sensor.
NOTE: During this first stage, do not open the door or
touch STOP/CLEAR pad.
4. When the sensor detects the vapor emitted from the
food, the display switches over to the remaining cooking
time and the timer counts down to zero.
At this time, the door may be opened to stir food, turn
it or season, etc.
5. When the timer reaches zero, an audible signal sounds.
The shut-off relay and cook relay are de-energized and
the power transformer, oven lamp, etc. are turned off.
6. Opening the door or touching the STOP/CLEAR pad,
the time of day will reappear on the display and the
oven will revert to an OFF condition.
DOOR OPEN MECHANISM
The door is opened by pushing the open button on the
control panel, refer to the Figure D-1.
When the open button is pushed, the open button pushes
up the switch lever, and then the switch lever pushes up
the the latch head. The latch heads are moved upward and
released from latch hook. Now the door will open.
Latch Hook
2nd. Latch
Switch
Monitor
Switch
Stop
Switch
Switch
Lever
Latch
Heads
Door
1st. Latch
Switch
Figure D-1. Door Open Mechanism
1ST. LATCH SWITCH, 2ND. LATCH SWITCH AND
STOP SWITCH
1. When the oven door is closed, the contacts (COM-NO)
must be closed.
2. When the oven door is opened, the contacts .(COM-
NO) must be opened.
MONITOR SWITCH
1. When the oven door is closed, the contacts (COM-NC)
must be opened.
2. When the oven door is opened, the contacts (COM-
NC) must be closed.
3. If the oven door is opened and the contacts (COM-NO)
of the 1st. latch switch and 2nd. latch switch fail to open,
the fuse M8A blows simultaneously with closing the
contacts (COM-NC) of the monitor switch.
CAUTION: BEFORE REPLACING A BLOWN FUSE M8A
TEST THE 1ST. LATCH SWITCH, 2ND.
LATCH SWITCH MONITOR SWITCH AND
MONITOR RESISTOR FOR PROPER OP-
ERATION.
MONITOR RESISTOR R 0.8
Ω
20W
The monitor resistor prevents the fuse M8A bursting when
the fuse M8A blows due to the operation of the monitor
switch.
ASYMMETRIC RECTIFIER
The asymmetric rectifier is a solid state device that pre-
vents current flow in both directions. And it prevents the
temperature rise of the power transformer by blowing the
fuse M8A when the high voltage rectifier is shorted.
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 asymmet-
ric rectifier or high voltage rectifier are shorted when the
each peak reverse voltage goes beyond the each rated
peak reverse voltage. (The process of blowing the fuse
M8A.)
FUNCTION OF IMPORTANT COMPONENTS
MICROWAVE
AH SENSOR
MICROWAVE