R-671 - 9
OPERATION SEQUENCE
OFF CONDITION
Closing the door activates the primary latch switch and the
stop switch.
IMPORTANT:
When the oven door is closed, the contacts COM-NC
of the monitor switch must be open. When the micro-
wave oven is plugged in a wall outlet (230V / 50Hz), the
line voltage is supplied to the noise filter.
Figure O-1 on page
32
1. The control unit is not energized. The display shows
nothing (Fig. O-1 (a)).
2. Open the door. The contacts (COM-NC) of the primary
latch switch are closed and the control unit is ener-
gized. Then contacts of relays RY1 and RY6 are
closed, and the oven lamp will light and the display will
flash
(Fig. -1(b)).
3. Close the door. The contacts (COM-NC) of the primary
latch switch are opened and the oven lamp will be
turned off. The display will stop flashing (Fig. O-1(c)).
NOTE: Energy save mode
1. If the oven has not been used for more than 2 minutes,
the contacts of the relay RY6 will be opened and the
control unit will be not energized. Open and close the
door, the control unit will resume.
2. If the clock is set, this energy save mode does not work.
MICROWAVE COOKING CONDITION
HIGH COOKING
Select the microwave cooking mode with the COOKING
MODE selector. Enter a desired cooking time by turning
the TIME/WEIGHT dial and start the oven by pressing
START button.
Function sequence Figure O-2 on page 33
CONNECTED COMPONENTS
RELAY
Oven lamp, Turntable motor
RY1
High voltage transformer
RY2
Grill heating element (Top)
RY3
Bottom heating element
RY4
Fan motor
RY5
Control unit
RY6
1. The line voltage is supplied to the primary winding of
the high voltage transformer. The voltage is converted
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 wavelength 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 cooking time is up, a signal tone is heard and
the relays RY1 + RY2 + RY5 go back to their home
position. The circuits to the oven lamp, high voltage
transformer, 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)
COM-NO
Closed
Opened
Primary latch Switch
COM-NC
Opened
Closed
Stop switch
COM-NO
Closed
Opened
COM-NO
Closed
Opened
Monitor Switch
COM-NC
Opened
Closed
The circuit to the high voltage transformer, fan motor and
turntable motor are cut off when the primary latch switch
and stop switch are made open. The oven lamp remains
on even if the oven door is opened after the cooking cycle
has been interrupted, because the relay RY1 stay closed.
Shown in the display is remaining time.
6. MONITOR SWITCH CIRCUIT
The monitor switch SW3 is mechanically controlled by
the oven door, and monitors the operation of the
primary latch switch SW1.
6-1. When the oven door is opened during or after the
cycle of a cooking program, the contacts (COM-NO)
of the primary latch switch SW1 and stop switch SW2
must open their contacts first. After that the contacts
(COM-NC) of the monitor switch SW3 can be closed.
6-2. When the oven door is closed, the contacts (COM-
NC) of the monitor switch SW3 must be opened. After
that the contacts (COM-NO) of the primary latch
switch SW1 and the stop switch SW2 are closed.
6-3. When the oven door is opened and the contacts
(COM-NO) of the primary latch switch SW1 remain
closed, the fuse F2 F8A will blow, because the moni-
tor switch is closed and a short circuit is caused.
MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW
COOKING
When the microwave oven is preset for variable cooking
power, the line voltage is supplied to the high voltage
transformer intermittently within a 32-second time base
through the relay contact which is coupled with the cur-
rent-limiting relay RY2. The following levels of microwave
power are given.
SETTING
800P 100%
560P
70%
400P
50%
240P
30%
80P
10%
32 sec. ON
Approx. 100%
24 sec. ON
8 sec. OFF
Approx. 70%
18 sec. ON
14 sec. OFF
Approx. 50%
12 sec. ON
20 sec. OFF
Approx. 30%
6 sec. ON
26 sec. OFF
Approx. 10%
Note:
The On/Off time ratio does not exactly correspond
to the percentage of microwave power, because
approx. 3 seconds are needed for heating up the
magnetron filament.
GRILL COOKING CONDITION
The oven has three grill cooking condition. They are the
TOP GRILL mode, BOTTOM GRILL mode and TOP AND
BOTTOM GRILL mode.
Содержание R-671(B)
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