R-64ST - 9
OPERATION SEQUENCE
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 closed 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 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 created.
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 RY3. The following levels of micro-
wave power are given.
SETTING
Note: The On/Off time ratio does not exactly corre-
spond to the percentage of microwave power,
because approx. 3 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 ). When the START +1min button
is touched, the following operations occur:
1. The numbers of the digital readout start the count
down to zero.
2. The oven lamp, cooling fan motor and turntable motor
are energized.
3. The relay RY2 is energized and the grill heating
elements are energized.
4. Now, the food is grilled by the grill heating elements.
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 O-1 on page 32
1. The display flashes "88:88"
2. To set any programmes or set the clock, you must first
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 +1min button.
Function sequence Figure O-2 on page 32
CONNECTED COMPONENTS RELAY
Oven lamp, Fan motor, Turntable motor RY1
High voltage transformer RY3
1. 230 volts A.C. 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 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 cooking time is up, a signal tone is heard and
the relays RY1 + RY3 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 monitored latch
switch, 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 stays closed. Shown in the display is
remaining time.
32 sec. ON
24 sec. ON
18 sec. ON
12 sec. ON
6 sec. ON
8 sec. OFF
14 sec. OFF
20 sec. OFF
26 sec. OFF
HIGH
MEDIUM HIGH
MEDIUM
MEDIUM LOW
LOW
Approx. 70%
Approx. 50%
Approx. 30%
Approx. 10%
Approx. 100%
R64ST_S.MANUAL 12/8/01, 11:00 am9
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