R-IX55
R-4X558
OPERATION SEQUENCE
OFF CONDITION
Closing the door activates all door interlock switches
(Upper latch switch, Lower latch switch and Stop switch)
IMPORTANT
When the oven door is closed, the monitor switch contacts
(COM-NC) must 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.
Figure O-1 on page 34 or 35
1. The display flashes “88:88”.
2. To set any programmes or set the clock, you must first
touch the STOP/CLEAR pad.
3. .I’ :
” 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
pads and start the oven with touching START pad.
Function sequence
Figure O-2 on page 34 or 35
CONNECTED COMPONENTS
RELAY
Oven lamp, Fan motor, Turntable motor
RYl
Power transformer
RY2
1.
2.
3.
4.
5.
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 secon-
dary winding.
The filament winding voltage (3.3 volts) heats the mag-
netron 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
SWITCH
DURING
DOOR OPEN
CONTACT
COOKING (NO COOKING)
Upper latch switch
COM-NO
Closed Open
Lower latch switch
COM-NO
Closed Open
Monitor switch
COM-NC
Open Closed
Stop switch
COM-NO
Closed
open
The circuits to the power transformer, fan motor and
turntable motor are cut off when the upper latch switch,
lower 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 (RYl) 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 upper and lower
latch switches.
6-l
6-2.
6-3.
When the oven door is opened during or after the
cycle of a cooking program, the upper latch switch,
lower latch switch and stop switch must open their
contacts first.
After that the contacts (COM-NC) of the monitor
switch can be closed.
When the oven door is closed, the contacts (COM-
NC) of the monitor switch must be opened. After that
the contacts of the upper latch switch, lower latch
switch and stop switch are closed.
When the oven door is opened and the contacts of
theupper latch switch, lower latch switch remain
closed. The fuse M8A will blow, because the monitor
switch is closed and a short circuit is caused.
VARIABLE COOKING
When the microwave oven is preset for variable cooking
power. Rated voltage is supplied to the power transformer
intermittently within a 32-second time base through the
relay contact which is coupled with the relay(RY2). The fol-
lowing levels of microwave power are given.
SETTING;
HIGH
32 sec. ON
MEDIUM HIGH 24 sec. ON
8 sec. OFF
Approx. 70%
MEDIUM
MEDIUM LOW
LOW
I
18 sec. ON 14 sec. OFF
Approx. 50%
12 sec. ON
20 sec. OFF
Approx. 30%
6 sec. ON 26 sec. OFF
Approx. 10%
1
NOTE:The ON/OFF time ratio does not exactly corre-
spond to the percentage of microwave power, be-
cause approx. 2 seconds are needed for heating up
the magnetron filament.
4
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