Operation Sequence - Sharp R-630A Service Manual

OPERATION SEQUENCE
OFF CONDITION
Closing the door activates all door interlock switches
(Monitored latch switch, and stop switch.)
IMPORTANT:
When the oven door is closed, the contacts COM-NC of
the monitor switch must be open. When the microwave
oven is plugged in a wall outlet (230V / 50Hz), the line
voltage is supplied to the point A1 + A3 in the control unit.
Figure 0-1 on page 30
1. The display flashes "88:88"
2. Tosetany programmes or setthe clock, you mustfirst
touch the STOP pad.
3. "\: " appears in display.
NOTE: When the oven door is opened, the oven lamp
comes on at this time.
MICROWAVE COOKING CONDITION
HIGH COOKING
Enter a desired cooking time by turning the Timer knob
and start the oven by touching START +1 min<}> button.
Function sequence Figure 0-2 on page 30
CONNECTED COMPONENTS RELAY
Oven lamp, Fan motor, Turntable motor RY1
High voltage transformer RY2
1. 230 volts A.C. is supplied to the primary winding of
the high voltage transformer. The voltage is con-
verted to about 3.3 volts A.C. output on the filament
winding and high voltage of approximately 2000 volts
A.C. on the secondary winding.
2. The filament winding voltage (3.3 volts) heats the
magnetron filament and the high voltage (2000 volts)
is sent to the voltage doubling circuit, where it is
doubled to negative voltage of approximately 4000
volts D.C..
3. The 2450 MHz microwave energy produced in the
magnetron generates a wave length of 12.24 cm.
This energy is channelled through the waveguide
(transport channel) into the oven cavity, where the
food is placed to be cooked.
4, When the cookingtime is up, asignal tone is heard and
the relays RY1 + RY2 go back to their home position.
The circuits to the oven lamp, high voltage trans-
former, fan motor and turntable motor are cut off.
5. When the oven door is opened during a cooking
cycle, the switches come to the following condition.
Switch ~~" Contact "Condition
During Oven Door
Cooking Open (No cooking)
Monitored Latch Switch COM-NO Closed Opened
Monitor Switch COM-NC Opened Closed
Stop Switch COM-NO Closed Opened
The circuit to the high voltage transformer, fan motor and
turntable motor are cut off when the 1st latch switch, 2nd.
latch switch and stop switch are made open. The oven
lamp remains on even ifthe oven door is opened afterthe
cooking cycle has been interrupted, because the relay
RY1 stay closed. Shown in the display is remaining time.
R-630A (W)
R-630A (IN)
R-630A (B)
6. MONITOR SWITCH CIRCUIT
The monitor switch is mechanically controlled by the
oven door, and monitors the operation of the moni-
tored latch switch.
6-1. When the oven door is opened during or after the
cycle of a cooking program, the monitored latch
switch must open its contacts (COM-NO) first. After
that the contacts (COM-NC) of the monitor switch
can be opened and the contacts of stop switch can
be opened.
6-2, When the oven door is closed, the contacts (COM-
NC) of the monitor switch must be opened and the
contacts (COM-NO) of the stop switch must be
closed and the contacts (COM-NO) of stop switch
must be closed first. After that the contacts of the
monitored latch switch are closed.
6-3. When the oven door is opened and the contacts of
the monitored latch switch remain closed, the fuse
F8A will blow, because the monitor switch are closed
and a short circuit is closed.
MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW
COOKING
When the microwave oven is preset for variable cooking
power, the 230 volts is supplied to the high voltage
transformer intermittently within a 32-second time base
through the relay contact which is coupled with the
current-limiting relay RY2. The following levels of micro-
wave power are given.
Note: The On/Off time ratio does not exactly corre-
spond to the percentage of microwave power,
because approx. 2 seconds are needed for
heating up the magnetron filament.
GRILL COOKING CONDITION (Figure O-3)
In this condition the food is cooked by grill heating
element energy. Program desired cooking time and grill
mode by turning the timer knob and touching mode select
button twice (x 2 (77). When the START +1 min@>button
is touched, the following operations occur:
1. The numbers of the digital readout start the count
down to zero.
2. The ovenlamp, cooling fan motor and turntable motor
are energized.
3. The relay RY3 is energized and the grill heating
elements are energized.
4. Now, the food is grilled by the grill heating elements.