Sharp R-8470, Руководство по обслуживанию

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OPERATION
DESCRIPTION OF OPERATING SEQUENCE
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following is a description of component functions
during oven operation.
OFF CONDITION
Closing the
door activates
both door interlock
switches: upper latch switch and lower latch switch.
(In this condition, the monitor switch contacts are
opened
stop switch is activated (contacts closed) by the
latch head, when the door is closed.
When oven is plugged in, the 240 volts A.C. is supplied
to the relay unit. (Figure O-l).
display will show flashing
To set any program or set the clock, you must first
touch the STOP/CLEAR (or STOP/CANCEL) pad.
The display will clear, and
will appear and
count up every minute.
Note: When the door is opened, the oven lamp comes
on.
2. A signal is input to the control unit, energizing the
coil of shut-off relay (RY6).
RY6 contacts close, completing a circuit to the
damper motor.
The damper motor now operates moving the damper
to the open position, thereby closing the contacts
of the damper switch inputs a signal to the control
unit.
The coil of relay RY6 is de-energized, opening its
contacts, thereby turning off the damper motor.
COOKING CONDITION
Program desired cooking time and Variable Cooking
Control by touching the NUMBER pads and the HIGH
pad of the Variable Cooking Control. When the COOK
(or START) pad is touched, the following operations
occur:
1. The contacts of relays are closed and components
connected to the relays are turned on as follows.
(For details, refer to Figure O-2)
RELAY CONNECTED COMPONENTS
RY-1 power transformer
RY-2 oven lamp/turntable motor
RY-3 convection motor
heating element
RY-5
fan motor
RY-6
damper motor
2. The 240 volts A.C. is supplied to the primary wind-
ing of the power transformer and
is converted
about 3 volts A.C. output on the filament winding,
and approximately 2200 volts A.C. on the high
voltage winding.
3. The filament winding voltage heats the magnetron
filament and the H.V. winding voltage is sent to a
voltage doubler circuit.
4. The microwave energy produced by the magnetron
is channeled through the waveguide into the cavity
feed-box, and then into the cavity where the food
is placed to be cooked.
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6.
Upon completion of the cooking time, the power
transformer, oven lamp, etc. are turned off, and the
generation of microwave energy is stopped. The
oven will revert to the OFF condition.
When the door is opened during a cook cycle,
monitor switch, stop switch, upper latch switch are
activated with the following results. The circuits to
the turntable motor, the cooling fan motor, and the
high voltage components are deenergized, the oven
lamp remains on, and the digital readout displays
the time still remaining in the cook cycle when the
door was opened.
7. The monitor switch is electrically monitoring the
operation of the upper latch switch and is mechan-
ically associated with the door so that it will func-
tion in the following sequence.
(1) When the door opens from a closed position,
the upper latch switch opens their contacts,
and then the monitor switch contacts close.
(2) When the door is closed from the open posi-
tion, the monitor switch contacts first open,
and then the contacts of the upper latch switch
close.
the upper latch switch failes with their contacts
closed when the door is opened, the closing of the
monitor switch contacts will form a short circuit
through the monitor fuse, upper latch switch , causing
the monitor fuse to blow.
When the Variable Cooking is programed, the 240 A.C.
voltage
is supplied
t o t h e p o w e r t r a n s f o r m e r
intermittently through the contacts of the relay which
is operated by the control unit within a 32 second time
base. The microwave power operation is as follows:
V A R I - M O D E
ON TIME OFF TIME
HIGH
32 sec. 0 sec.
(approx. 100% power)
24 sec.
8 sec.
(approx. 70% power)
M E D I U M
18 sec.
14 sec.
(approx. 50% power)
MED.LOW( DEFROST)
12 sec.
20 sec.
(approx. 30% power)
L O W
6 sec. 26 sec.
(approx. 10% power)
Note: The ON/OFF time ratio does not correspond
with the percentage of microwave power, be-
cause approx. 2 seconds are needed for heating
of the magnetron filament.
CONVECTION COOKING CONDITION
Program desired convection temperature by touching
the CONVECTION pad and the temp. pad.
When the START pad is touched, the following oper-
ations occur:
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