Jenn-Air JMD2124WS Technical Education - Theory Of Operation

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THEORY OF OPERATION

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.

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