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OPERATION
DESCRIPTION OF OPERATING SEQUENCE
The following is a description of component functions
during oven operation.
(RD71101 U)
OFF CONDITION
Closing the door
activates both door interlock
switches: upper latch switch, lower latch switch and
stop switch.
(In this condition, the monitor switch
contacts are opened.)
When oven is plugged in, 240 volts A.C. is supplied to
the relay unit. (Figure O-l).
’
1. The display will show flashing “88:88”.
To set any program or set the clock;- you must first
touch the STOP/CLEAR pad. The display will clear,
and I:00 will appear and count up every minute.
Note: When the door is opened, the oven lamp comes
2. A si;al is input to the control unit, energizing the
coil of shut-off relay (RY6).
RY6 contacts close, completing a circuit to the
damper motor.
The damper motor now operates moving the damper
to the open position, thereby closing the contacts
of the damper switch inputs a signal to the control
unit.
The coil of relay RY6 is de-energized, opening its
contacts, thereby turning off the damper motor.
(RD71207U)
COOKING CONDITION
HIGH COOKING
Program desired cooking time and Variable Cooking
Control by touching the NUMBER pads and the HIGH
pad of the Variable Cooking Control. When the START
pad is touched, the following operations occur:
1.
The contacts of relays are closed and components
connected to the relays are turned on as follows.
(For details, refer to Figure O-2)
2.
3.
4.
RELAY
CONNECTED COMPONENTS
RY-1
power transformer
RY-2
oven lamp/turntable motor
RY-3
convection motor
RY-4
convection heater
RY-5
fan motor
RY-6
damper motor
240 volts A.C. is supplied to the primary winding
of the power transformer and is converted to about
3.3 volts A.C. output on the filament winding, and
approximately 2043 volts A.C. on the high voltage
winding.
The filament winding voltage heats the magnetron
filament and the H.V. winding voltage is sent to a
voltage doubler circuit.
The microwave energy produced by the magnetron
is channeled through the waveguide into the cavity
feed-box, and then into the cavity where the food
is placed to be cooked.
5.
6.
7 .
Upon completion of the cooking time, the power
transformer, oven lamp, etc. are turned off, and the
generation of microwave energy is stopped. The
oven will revert to the OFF condition.
When the door is opened during a cook cycle,
monitor switch, upper latch switch, lower latch
switch and stop switch. are activated with the fol-
lowing results. The circuits to the turntable motor,
the cooling fan motor, and the high voltage com-
ponents are deenergized, the oven lamp remains on,
and the digital readout displays the time still re-
maining in the cook cycle when the door was
opened.
The monitor switch is electrically monitoring the
operation of the upper latch switch and is mechan-
ically associated with the door so that it will func-
tion in the following sequence.
(1) When the door opens from a closed position,
the upper latch switch and lower latch switch
open their contacts, and then the monitor
switch contacts close.
If
(2) When the door is closed from the open posi-
tion, the monitor switch contacts first open,
and then the contacts of the upper latch switch
and lower latch switch close.
the common and normal open contacts of upper
latch switch fail with their contacts closed when the
door is opened, the closing of the monitor switch
contacts will form a short circuit through the fuse and
upper latch switch, causing the monitor fuse to blow.
MED HIGH, MED, MED LOW (DEFROST), LOW,
HOLD COOKING
When Variable Cooking Power is programed, the 240
volts A.C. is supplied to the power transformer
intermittently through the contacts of relay( RY-2)
which is operated by the control unit within a 32 sec-
ond time base. Microwave power operation is as fol-
lows:
VARI-MODE
ON TIME
OFF TIME
HIGH
32 sec.
0 sec.
(100% power)
MED HIGH
24 sec.
8 sec.
(approx. 70% power)
MED
18 sec.
14 sec.
(approx. 50% power)
MED LOW (DEFROST)
12 sec.
20 sec.
(approx. 30% power)
LOW
6 sec. 26 sec.
(approx. 10% power)
HOLD
0 sec.
32 sec.
(0% power)
Note: The ON/OFF time ratio does not correspond
with the percentage of microwave power, be-
cause approx. 2 seconds are needed for heating
of the magnetron filament.
(RD71401 U)