R-21JCA-F
6
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
The following is a description of component functions during
oven operation.
OFF CONDITION
Closing the door activates 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 noise
filter and the control unit (Figure O-1).
COOKING CONDITION
When the Light Up Dial is turned, 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/ Antenna 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 3.2 volts A.C.
output on the filament winding, and approximately 2150
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, secondary interlock switch,
relay (RY2) and primary interlock relay(RY1) are activated
with the following results. The circuits to the antenna motor,
the cooling fan motor, the oven lamp and the high voltage
components are de-energized, and the cooking program
will be canceled when the door was opened.
7. The monitor switch electrically monitors the operation of the
secondary interlock switch and primary interlock relay(RY1)
and is mechanically associated with the door so that it will
function in the following sequence.
(1) When the door opens from the closed position, the primary
interlock relay(RY1) and secondary interlock switch open
their contacts. Then the monitor switch contacts close.
(2) When the door 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.
If the secondary interlock switch and primary interlock relay (RY1) fail
with the contacts closed when the door is opened, the closing of the
monitor switch contacts will form a short circuit through the monitor
fuse, secondary interlock switch, and primary interlock relay(RY1),
causing the monitor fuse to blow.
