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Theory of Operation
TECHNICAL OPERATION
NOTE: The following is a description of component
functions during oven operation.
OFF CONDITION:
Closing the drawer activates the door sensing switch and
secondary interlock switch. (In this condition, the monitor
switch contacts are opened.) When oven is plugged in,
3-620 vac is supplied to the control unit. (See Figure 3-1)
•
The display will show À ashing "Enjoy Your Drawer
Touch Clear and Touch Clock".
•
To set any program or set the clock, you must ¿ rst
touch the STOP/CLEAR pad. The display will clear,
and " : " will appear.
COOKING CONDITION:
Program desired cooking time by touching the NUMBER
pads. Program the power level by touching the POWER
LEVEL pad and then a Number 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.
(See Figure 3-1)
RELAY
CONNECTED COMPONENTS
RY-1
oven lamp/stir fan motor/fan motor
RY-2
power transformer
2.
20 vac is supplied to the primary winding of the
power transformer and is converted to about 3.3 vac
output on the ¿ lament winding, and approximately
2370 vac on the high voltage winding.
3.
The ¿ lament winding voltage heats the magnetron
¿ lament 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 drawer is opened during a cook cycle,
the monitor switch, door sensing switch, secondary
interlock switch, relay (RY3-6) and primary interlock
relay are activated with the following results. The
circuits to the stir fan 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.
Drawer Microwave
7.
The monitor switch electrically monitors the operation
of the secondary interlock switch and secondary
interlock relay and is mechanically associated with
the drawer so that it will function in the following
sequence.
8.
When the drawer opens from the closed position, the
primary interlock relay (RY2) and secondary interlock
switch open their contacts. And contacts of the relay
(RY3-6) remains closed. Then the monitor switch
contacts close.
9.
When the drawer is closed from the open position,
the monitor switch contacts open ¿ rst. Then the
contacts of the secondary interlock switch and door
sensing switch close. And contacts of the relay
(RY3-6) open.
If the secondary interlock switch and primary interlock
relay (RY2) fail with the contacts closed when the drawer
is opened, the closing of the monitor switch contacts will
form a short circuit through the fuse, secondary interlock
switch, relay (RY3-6) and secondary interlock relay
(RY2), causing the fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING:
VARI-MODE
Power 10(P-HI)
(100% power)
Power 10(P-90)
(approx 90% power)
Power 10(P-80)
(approx 80% power)
Power 10(P-70)
(approx 70% power)
Power 10(P-60)
(approx 60% power)
Power 10(P-50)
(approx 50% power)
Power 10(P-40)
(approx 40% power)
Power 10(P-30)
(approx 30% power)
Power 10(P-20)
(approx 20% power)
Power 10(P-10)
(approx 10% power)
Power 10(P-0)
(0% power)
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
¿ lament.
3-6
ON TIME
OFF TIME
32 sec.
0 sec.
30 sec.
2 sec.
26 sec.
6 sec.
24 sec.
8 sec.
22 sec.
10 sec.
18 sec.
14 sec.
16 sec.
16 sec.
12 sec.
20 sec.
8 sec.
24 sec.
6 sec.
26 sec.
0 sec.
32 sec.
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