13
DESCRIPTION AND FUNCTION OF COMPONENTS
DOOR OPEN MECHANISM
The door is opened by pushing the open button on the con-
trol panel, refer to the Figure D-1. When the open button is
pushed, the open button pushes up the switch lever, and
then the switch lever pushes up the latch head. The latch
heads are moved upward and released from latch hook.
Now the door will open.
Figure D-1. Door Open Mechanism
PRIMARY SWITCH, SECONDARY SWITCH & DOOR
SENSING SWITCH
The primary switch and secondary switch mounted parrallel
to each other horizontally in the lower positions of the latch
hook, the door sensing switch is mounted horizontally in
the upper position of the latch hook. They are activated by
the latch head on the door. When the door is opened, the
switches interrupt the power to all high voltage components,
except the oven lamp . A cook cycle cannot take place un-
til the door is firmly closed thereby activating all interlock
switches. The secondary interlock system consists of the
door sensing switch and the secondary interlock relay located
on the control circuit board.
MONITOR SWITCH
The monitor switch is activated (the contacts opened) by the
latch head on the door while the door is closed. The switch
is intended to render the oven inoperative, by means of
blowing the monitor fuse, when the contacts of the primary
switch fail to open when the door is opened.
Functions:
1. When the door is opened, the monitor switch contact
close (to the ON condition) due to their being normally
closed. At this time the secondary interlock relay, primary
switch and secondary 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, primary switch and secondary switch contacts
close. (On opening the door, each of these switches
operate inversely.)
3. If the door is opened, primary switch and contacts fail
to open, the monitor fuse blows simultaneously with
closing of the monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN MONITOR
FUSE, TEST MONITOR SWITCH AND PRIMA-
RY SWITCH FOR PROPER OPERATION. (RE-
FER TO CHAPTER "TEST PROCEDURE").
NOTE: MONITOR FUSE, AND MONITOR SWITCH ARE
REPLACED AS AN ASSEMBLY.
TURNTABLE MOTOR
The turntable motor rotates the turntable located on the
bottom of the oven cavity, so that the foods on the turntable
cook evenly during cooking. The turntable 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 foods. 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 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.
CAVITY TEMPERATURE FUSE
The cavity temperature fuse located on the top of the oven
cavity, is designed to prevent damage to the oven by fire.
If the food load is overcooked, by either error in cook time
or defect in the control unit, the cavity temperature fuse
will open.
Under normal operation, the cavity temperature fuse remains
closed. However, when abnormally high temperatures are
reached within the oven cavity, the cavity temperature fuse
will open at 302
o
F(150
o
C) causing the oven to shut down.
NOTE: This is fuse. It does not reset.
MAGNETRON TEMPERATURE FUSE
The magnetron temperature fuse located near the magne-
tron is designed to prevent damage to the magnetron if an
over heated condition develops in the tube due to cooling
fan failure, obstructed air guide, dirty or blocked air intake,
etc.
Under normal operation, the magnetron temperature fuse
remains closed. However, when abnormally high tempera-
tures are reached within the magnetron, the magnetron
temperature fuse will open at 302
o
F(150
o
C) causing the
oven to shut down.
NOTE: This is fuse. It does not reset.
Door Sensing
Switch
Monitor Switch
Switch Lever
Secondary
Switch
Latch Heads
Door
Primary
Switch
