Theory Of Operation; Microwave Operating Sequence - Jenn-Air JMD2124WS Technical Education

MICROWAVE OPERATING SEQUENCE

The following is a description of component
functions during oven operation.
OFF CONDITION
Closing the drawer activates the door sens-
ing 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.
1. The display will show flashing "Enjoy
Your Drawer Touch Clear and Touch
Clock".
To set any program or set the clock, you
must first 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.
RELAY CONNECTED COMPONENTS
RY-1 oven lamp/stir fan motor/fan motor
RY-2 power transformer
2. 120 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
2370 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.

THEORY OF OPERATION

4. The microwave energy produced by the
magnetron is channelled through the
waveguide into the cavity feedbox, 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 micro-
wave energy is stopped. The oven will re
vert to the OFF condition.
6. When the drawer is opened during a cook
cycle, the monitor switch, door sensing
switch, secondary interlock switch, relay
(RY1) 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 compo-
nents are de-energized, the oven lamp
remains on, and the digital read-out dis-
plays the time still remaining in the cook
cycle when the door was opened.
7. The monitor switch electrically monitors
the operation of the secondary inter lock
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 (RY1)
remains closed. Then the monitor switch
contacts close.
9. When the drawer is closed from the open
position, the monitor switch contacts open
first. Then the contacts of the secondary
interlock switch and door sensing switch
close. And contacts of the relay (RY1)
open.
If the secondary interlock switch and pri
mary 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
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