6
DCM24B
DCM24R
DCM24S
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
The following is a description of component functions during
oven operation.
OFF CONDITION
Closing the door activates the door sensing switch and
secondary interlock switch. (In this condition, the monitor
switch contacts are opened.)
When oven is plugged in, 120 volts A.C. is supplied to the
control unit. (Figure O-1).
1. The display will show "WELCOME PRESS CLEAR AND
PRESS CLOCK".
To set any program or set the clock, you must first touch
the STOP/CLEAR pad. The display will clear, and " : "
will appear.
NOTE: When the door is opened, the oven lamp comes on.
2. A signal is input to the control unit, energizing the coil of
shut-off relay (RY-4). RY4 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 RY-4 is de-energized,
opening its contacts, thereby turning off the damper motor.
COOKING CONDITION
Program desired cooking time Variable Cooking Control by
touching the NUMBER pads and the power level pad. 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)
RELAY
CONNECTED COMPONENTS
RY-1
Oven lamp/Turntable motor
RY-2
Power transformer
RY-3
Heating element
RY-4
Damper motor
RY-5
Convection motor
RY-6
Fan motor
2. 120 volts A.C. is supplied to the primary winding of the
power transformer and is converted to about 3 volts A.C.
output on the filament winding, and approximately 2360
volts A.C. on the high voltage winding.
3. The filament winding voltage heats the magnetron
filament and the H.V. winding voltage is sent to a voltage
doubler circuit.
4. The microwave energy produced by the magnetron is
channelled through the waveguide into the cavity feed-
box, and then into the cavity where the food is placed to
be cooked.
5. 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.
6. When the door is opened during a cook cycle, monitor
switch, door sensing switch, the primary interlock relay
and the secondary interlock switch are activated with the
following results. The circuits to the turntable motor, the
cooling fan motor, and the high voltage components are
de-energized, the oven lamp remains on, and the digital
read-out displays the time still remaining in the cook
cycle when the door was opened.
7. The monitor switch is electrically monitoring the operation
of the primary interlock relay and the secondary interlock
switch and is mechanically associated with the door so
that it will function in the following sequence.
(1) When the door opens from a closed position, the primary
interlock relay and the secondary interlock switch open
their contacts, and then the monitor switch contacts close.
(2) When the door is closed from the open position, the
monitor switch contacts first open, and then the contacts
of the primary interlock relay and the secondary interlock
switch close.
If the primary interlock relay and the secondary interlock
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 monitor fuse, primary interlock
relay and the secondary interlock switch, causing the moni-
tor fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING
When Variable Cooking Power is programmed, the 120
volts A.C. is supplied to the power transformer intermittently
through the contacts of relay (RY-2). RY-2 is operated by
the control unit within an varying time base. Microwave
power operation is as follows:
VARI-MODE
ON TIME
OFF TIME
Power 10(P-HI) (100% power)
32 sec.
0 sec.
Power 9(P-90) (approx. 90% power)
30 sec.
2 sec.
Power 8(P-80) (approx. 80% power)
26 sec.
6 sec.
Power 7(P-70) (approx. 70% power)
24 sec.
8 sec.
Power 6(P-60) (approx. 60% power)
22 sec.
10 sec.
Power 5(P-50) (approx. 50% power)
18 sec.
14 sec.
Power 4(P-40) (approx. 40% power)
16 sec.
16 sec.
Power 3(P-30) (approx. 30% power)
12 sec.
20 sec.
Power 2(P-20) (approx. 20% power)
8 sec.
24 sec.
Power 1(P-10)(approx. 10% power)
6 sec.
26 sec.
Power 0(P-0) (0% power)
0 sec.
32 sec.
Note:
The ON/OFF time ratio does not correspond with
the percentage of microwave power, because
approx. 2 seconds are needed for heating of the
magnetron filament.
CONVECTION COOKING CONDITION
PREHEATING CONDITION
Program desired convection temperature by touching the
CONVECTION pad and the Temperature pad. When the
START pad is touched, the following operations occur:
1. The coil of shut-off relays (RY1, RY3,RY5 and RY6) are
energized, the oven lamp, cooling fan motor, turntable
motor and convection motor are turned on.
2. The coil of relay (RY4) is energized by the control unit.
The damper is moved to the closed position, opening the