Sharp R-8470, Service Manual

Page: 11 / 54

-8470
R-8570
Usually, the damper is open position except during the
convection cooking.
Damper position is set automatically by damper motor,
damper switch, motor cam and damper shaft.
These components are operated according to the signal
that judges the microwave cooking or convection
cooking operation in the control unit.
Microwave Cooking:
Damper is in the open position, because a portion of
cooking air is channeled through the cavity to remove
steam and vapors given off from the heating foods.
It is then exhausted at the top of the oven cavity into
a condensation compartment.
Convection Cooking:
Damper is in the closed position, so that no hot air will
be allowed to leak out the oven cavity.
Damper Operation
1. When power supply cord is plugged in:
l - l .
1-2.
1-3.
I-4.
l - 5 .
When power supply cord is plugged in, a sig-
nal is sensed in the control unit, and operates
the shut-off relay (RY6).
Contacts of shut-off relay (RY6) close, then
the damper motor is energized, opening the
damper door.
When damper is moved to the open position
by the damper cam damper switch is closed
(ON position).
The signal of damper switch is re-sensed in
the control unit and shut-off relay (RY6) is
turned off.
The 240 volts A.C. to the damper motor is
stopped and the motor turns off.
2. When oven is microwave cooking:
Damper is in the open position.
3. When oven is convection cooking:
3 - l .
3-2.
3-3.
3-4.
Damper motor is energized by touching the
convection, temperature and START pads.
When damper is in the closed position
(damper switch is OFF), its signal is sensed
by the control unit, and shut-off relay (RY6)
is de-energized.
The damper is held in the closed position
during the convection cooking operation.
At the end of the convection cooking, the
shut-off relay (RY6) is energized, and damper
is returned to the open position.
DAMPER
DAMPER
DAMPER CAM
MOTOR