R-21JCA-F
8
DESCRIPTION AND FUNCTION OF COMPONENTS
DOOR OPEN MECHANISM
The door is opened by grasping the door handle, refer to Figure
D-1.
When the door handle is grasped, the handle lever is pulled.
And then the upper and lower latch heads are moved upward
by the handle lever, and they are released from the latch
hook. Now the door will open.
Figure D-1. Door Open Mechanism
DOOR SENSING AND SECONDARY INTERLOCK
SWITCHES
The secondary interlock switch is mounted in the upper posi-
tion of the latch hook and the door sensing switch in the primary
interlock system is mounted in the lower position of the latch
hook. The secondary interlock switch is activated by the latch
switch lever A. The latch switch lever A is activated by the upper
latch head. The door sensing switch is activated by the latch
switch lever C. The latch switch lever C is activated by the lower
latch head. When the door is opened, the switches interrupt the
power to all high voltage components. A cook cycle cannot take
place until the door is firmly closed thereby activating both
interlock switches. The primary interlock system consists of the
door sensing switch and primary interlock relay located on the
control circuit board.
MONITOR SWITCH
The monitor switch is activated (the contacts opened) by the
latch switch lever B on the latch hook while the door is closed.
The latch switch lever B is activated by the lower latch head.
The switch is intended to render the oven inoperative, by
means of blowing the monitor fuse, when the contacts of the
primary interlock relay (RY1) and secondary interlock switch
fail to open when the door is opened.
Functions:
1. When the door is opened, the monitor switch contacts
close (to the ON condition) due to their being normally
closed. At this time the primary interlock relay (RY1) and
secondary interlock switch are in the OFF condition
(contacts open) due to their being normally open contact
switches.
2. As the door goes to a closed position, the monitor switch
contacts are first opened and then the door sensing switch
and the secondary interlock switch contacts close. (On
opening the door, each of these switches operate inversely.)
3. If the door is opened, and the primary interlock relay (RY1)
Latch Hook
Latch Switch
Lever A
Latch Switch
Lever B
Latch Switch
Lever C
Latch Head
Latch Head
Handle
Lever
Door
Handle
Latch
Lever
Secondary
Interlock
Switch
Monitor
Switch
Door
Sensing
Switch
and secondary interlock switch contacts fail to open, the
monitor fuse blows simultaneously with closing of the
monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN MONITOR
FUSE TEST THE DOOR SENSING SWITCH,
P R I M A R Y I N T E R L O C K R E L A Y ( R Y 1 ) ,
SECONDARY INTERLOCK SWITCH AND
MONITOR SWITCH FOR PROPER OPERATION.
(REFER TO CHAPTER “TEST PROCEDURE”).
NOTE: MONITOR FUSE AND MONITOR SWITCH ARE
REPLACED AS AN ASSEMBLY.
ANTENNA MOTOR
The antenna motor rotates the stirrer antenna located on the
bottom of the oven cavity, so that the food on the ceramic
shelf is cooked evenly during cooking. The antenna motor
may turn in either direction.
COOLING FAN MOTOR
The cooling fan motor drives a blade which draws external
cool air. This cool air is directed through the air vanes sur-
rounding the magnetron and cools the magnetron. This air is
channelled through the oven cavity to remove steam and
vapors given off from the heating food. It is then exhausted
through the exhausting air vents at the oven cavity.
MONITOR FUSE
1. The monitor fuse blows when the contacts (COM-NO) of
the primary interlock relay (RY2) and secondary interlock
switch remain closed with the oven door open and when
the monitor switch closes.
2. If the wire harness or electrical components are short-
circuited, this monitor fuse blows to prevent an electric
shock or fire hazard.
THERMAL CUT-OUT 145˚C (MAGNETRON)
This thermal cut-out protects the magnetron against over-
heating. If the temperature goes up higher than 293˚F (145˚C)
because the fan motor is interrupted or the ventilation open-
ings are blocked, the thermal cut-out will open and line
voltages to the high voltage transformer will be cut off and the
operation of the magnetron will be stopped. The thermal cut-
out will not resume.
THERMAL CUT-OUT 125˚C (OVEN)
The thermal cut-out located on the top of the oven cavity is
designed to prevent damage to the oven if the food in the
oven catches fire due to over heating produced by improper
setting of the cooking time or failure of control unit. Under
normal operation, the oven thermal cut-out remains closed.
However, when abnormally high temperatures are reached
within the oven cavity, the oven thermal cut-out will open at
257˚F(125˚C) causing the oven to shut down. The thermal
cut-out will not resume.
NOISE FILTER
The noise filter prevents the radio frequency interference that
might flow back in the power circuit.
