R-4H56
4
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 31
1. The display flashes “88:88”.
2. Tosetanyprogramsorsettheclock,youmustfirsttouch
the STOP/CLEAR pad.
3. “ : “appearsinthe displayandthe timecountsup every
minute.
NOTE: When the oven door is opened, the oven lamp
comes on at this time.
MICROWAVE COOKING CONDITION
HIGH COOKING
EnteradesiredcookingtimewiththetouchingNumberpads
and start the oven with touching START pad.
Function sequence
Figure O-2 on page 31
CONNECTED COMPONENTS RELAY
Oven lamp, Fan motor, Turntable motor RY1
Power transformer RY2
1. Rated voltage is supplied to the primary winding of the
powertransformer.Thevoltageisconvertedtoabout3.3
volts A.C. output on the filament winding and high
voltageofapproximately2000voltsA.C.onthesecondary
winding.
2. The filament winding voltage (3.3 volts) heats the
magnetron filament and the high voltage (2000 volts) is
senttothevoltagedoublingcircuit,whereitisdoubledto
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)intotheovencavity,wherethefoodisplacedto
be cooked.
4. When the cooking time is up, a signal tone is heard and
the relays (RY1+RY2) go back to their home position.
The circuits to the oven lamp, power transformer, fan
motor and turntable motor are cut off.
5. When the door is opened during a cook cycle, the
switches come to the following condition
CONDITION
DURING DOOR OPEN
SWITCH CONTACT COOKING (NOCOOKING)
Upper latch switches 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
therelay(RY1) staysclosed.Shownin the displayisthe
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.
6-1 Whentheoven door isopenedduringor after thecycle
of a cooking program, the upper latch switch, lower
latch switch and stop switch must open their contacts
first.
Afterthatthecontacts(COM-NC)ofthemonitorswitch
can be closed.
6-2. Whentheoven door isclosed,thecontacts (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.
6-3. When the oven door is opened and the contacts of the
upperlatchswitchandlowerlatchswitchremainclosed.
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.Ratedvoltageissuppliedtothepowertransformer
intermittently within a 32-second time base through the
relay contact which is coupled with the relay (RY2). The
following levels of microwave power are given.
SETTING;
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%
NOTE: TheON/OFFtimeratiodoesnotexactlycorrespond
to the percentage of microwave power, because
approx. 2 seconds are needed for heating up the
magnetron filament.
SENSOR COOKING CONDITION
Using the SENSOR COOK, REHEAT SENSOR or SEN-
SOR INSTANT ACTION function, the foods are cooked or
defrosted without figuring time, power level or quantity.
When the oven senses enough steam from the food, it
relaystheinformationtoitsmicroprocessorwhichwillcalcu-
latethe remainingcooking time andpower levelneeded for
