4
R-7A55(W)/(B)
R-7E45(W)/(B)
OPERATION SEQUENCE
OFF CONDITION
Closing the oven door activates all door interlock switches
(1st. latch switch, 2nd. latch switch and stop switch.
IMPORTANT:
When the oven door is closed, the contacts COM-NC of the
monitor switch SW4 must be open and the contacts (COM-
NO) must be closed. When the microwave oven is pluged in
a wall outlet (220 - 230V / 50Hz), 220 - 230 volts A.C. is
supplied to the point H1 + H3 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 key.
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 with the touching Time key and
start the oven with touching START key.
Function sequence Figure O-2 on page 32
CONNECTED COMPONENTS
RELAY
Oven lamp, Fan motor, Turntable motor
RY1
High voltage transformer
RY1 + RY2
Fan motor
RY6
1. 220-230 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 + RY2 + RY6 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)
1st latch Switch
COM-NO
Closed
Opened
Monitor Switch
COM-NO
Closed
Opened
Monitor Switch
COM-NC
Opened
Closed
2nd latch switch
COM-NO
Closed
Opened
Stop switch
COM-NO
Closed
Opened
The circuit to the high voltage transformer, is cut off when the
contact of relay RY2 contacts COM-NO of the 1st latch
switch, and monitor switch SW4 are made open. The circuit
to the fan motor is cut off when the relay RY6 is made open.
The circuit to the turntable motor is cut off when the contacts
COM-NO of the 2nd latch switch are made open. The relay
RY2 and RY6 are made open when the door is opened. 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 SW4 is mechanically controlled by
the oven door, and monitors the operation of the 1st latch
switch SW1.
6-1. When the oven door is opened during or after the cycle
of a cooking program, the 1st latch switch SW1 and stop
switch SW3 must open their contacts (COM-NO) first.
After that the contacts (COM-NC) of the monitor switch
SW4 can be closed and the contacts (COM-NO) of
monitor switch SW4 are made open, and the contacts
(COM-NO) of the 2nd latch switch SW2 can be opened.
6-2. When the oven door is closed. The contacts (COM-NC)
of the monitor switch SW4 must be opened and the
contacts (COM-NO) of monitor switch SW4 must be
closed, and the contacts (COM-NO) of the 2nd latch
switch SW2 must be closed. After that the contacts of
the 1st latch switch SW1 and the stop switch SW3 are
made closeed.
6-3. When the oven door is opened and the contacts of the
1st latch switch SW1 remain closed, the fuse F2 F6.3A
will blow. Because the relay RY1 and monitor switch
SW4 are closed and a short circuit is caused.
CONVECTION COOKING CONDITION
PREHEATING CONDITION (Figure O-3)
Program desired convection temperature by touching CON-
VECTION key. When the START key is touched, the follow-
ing operations occur:
1. The coil of shut-off relays RY1 ,RY4 and RY6 are
energized, the oven lamp, cooling fan motor, turntable
motor and convection motor are turned on.
Note: The On/Off time ratio does not exactly correspond to
the percentage of microwave power, because approx.
2 seconds are needed for heating up the magnetron
filament.
32 sec. ON
24 sec. ON
18 sec. ON
12 sec. ON
6 sec. ON
8 sec. OFF
14 sec. OFF
20 sec. OFF
28 sec. OFF
HIGH
MEDIUM
HIGH
MEDIUM
MEDIUM
LOW
LOW
Approx. 70%
Approx. 50%
Approx. 30%
Approx. 10%
MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW
COOKING
When the microwave oven is preset for variable cooking
power, the 220 - 230 volts A.C. power 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 microwave
power are given.
