R -3A54
R-3E54
OPERATING SEQUENCE
OFF CONDITION
Closing the door activates all door interlock switches
(1 st latch switch, 2nd latch switch and stop switch).
IMPORTANT
When the oven door is closed, the monitor switch
contacts (COM -
NC) rnust be open.
When the microwave oven is plugged in a wall outlet.
Rated voltage is supplied to the point A3+ A5 in the
control unit.
1.
3
L.
3.
Figure O-l on page 29
The display flashes “88:88”. -
To set any programmes or set the clock, you must
first touch the STOP/CLEAR key.
11 .
. II appears in the display and the time counts
up every minute.
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 with the touching Number
key and start the oven with touching START key.
Function sequence
1.
2.
3.
4.
5.
Figure O-2 on page 29
CONNECTED COMPONENTS
RELAY
Oven lamp, Fan motor, Turntable motor
RYl
Power transformer
RY2
Rated voltage is supplied to the primary winding of
the power 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.
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..
The 2450 MHz microwave energy produced in the
magnetron generates a wave length of 12.24 cm.
This energy is channeled through the waveguide
(transport channel) into the oven cavity, where the
food is placed to be cooked.
When the cooking time is up, a signal tone is heard
and the relays RYI + RY2 go back to their home
position. The circuits to the oven lamp, power
transformer, fan motor and turntable motor are cut
off.
When the door is opened during a cook cycle, the
switches come to the following condition.
CONDITION
DURING
DOOR OPEN
SWITCH
CONTACT
COOKING (NO COOKING)
1st latch switch
COM - NO
Closed
Open
Monitor switch
COM -NC
Open
Closed
2nd latch switch COM - NO
Closed
Open
Stop switch COM - NO
Closed
Open
The circuits to the power 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 if the oven door is
opened after the cooking cycle has been inter-
rupted, because the relay RYI stays closed. Shown
in the display is the remaining time.
6. MONITOR SWITCH CIRCUIT
The monitor switch is mechanically controlled by
oven door, and monitors the operation of the 1 st
and 2nd latch switches.
6-l
When the oven door is opened during or after the
cycle of a cooking program, the 1 st latch, 2nd
latch and stop switches must open their contacts
first. After that the contacts (COM - NC) of the
monitor switch can be closed.
6-2
When the oven door is closed, the contacts
(COM -NC) of the monitor switch must be
opened. After that the contacts of the 1st latch,
2nd latch and stop switches are closed.
6-3. When the oven door is opened and the contacts
of the 1st and 2nd latch switches remain closed,
the fuse M8A will blow because the monitor
switch is closed and a short circuit is caused.
MEDIUM HIGH, MEDIUM, MEDIUM LOW,
LOW COOKING
When the microwave oven is preset for variable cook-
ing power, 240 volts A.C. power is supplied to the
power transformer intermittently within a 32-second
time base through the relay contact which is coupled
with the current-limiting relay. The following levels of
microwave power are given.
SETTING
32 sec. ON
HIGH
MEDIUM HIGH
MEDIUM
MEDIUM LOW
LOW
24 sec. ON 8 sec. OFF
18 sec. ON
14 sec. OFF
J-1 Approx. 50%
12 sec. ON 20 sec. OFF
6 sec. ON 26 sec. OFF
J-1 Approx 10%
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.
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