R-671 - 9
OPERATION SEQUENCE
OFF CONDITION
Closingthedooractivatestheprimarylatchswitchandthe
stop switch.
IMPORTANT:
When the oven door is closed, the contacts COM-NC
of the monitor switch must be open. When the micro-
waveovenispluggedinawalloutlet(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. Openthedoor.Thecontacts(COM-NC)oftheprimary
latch switch are closed and the control unit is ener-
gized. Then contacts of relays RY1 and RY6 are
closed,andtheoven lamp will light and the displaywill
flash (Fig. -1(b)).
3. Closethedoor.Thecontacts(COM-NC)oftheprimary
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. Ifthe oven hasnotbeenusedfor more than2minutes,
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. Iftheclockisset,thisenergysavemodedoesnotwork.
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
thehighvoltagetransformer.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
magnetronfilamentandthehighvoltage(2000volts)is
sentto the voltage doublingcircuit, where it isdoubled
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
energyischannelledthroughthewaveguide(transport
channel)intotheovencavity,wherethefoodisplaced
to be cooked.
4. Whenthecookingtimeisup,asignaltoneisheardand
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. Whentheovendoorisopenedduringacookingcycle,
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
oneven if the ovendoor is openedafter the cooking cycle
hasbeeninterrupted,becausetherelayRY1 stayclosed.
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)
oftheprimarylatch switchSW1andstopswitchSW2
must open their contacts first. After that the contacts
(COM-NC)of the monitor switchSW3canbe closed.
6-2. When the oven door is closed, the contacts (COM-
NC)ofthemonitorswitchSW3mustbeopened.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-limitingrelay RY2. The followinglevels of microwave
power are given.
SETTING
800P100%
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: TheOn/Offtimeratiodoesnotexactlycorrespond
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
TOPGRILL mode, BOTTOM GRILLmodeandTOPAND
BOTTOM GRILL mode.
