11
R-520LK
R-520LW
DESCRIPTION AND FUNCTION OF COMPONENTSDOOR 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
DOOR SENSING AND PRIMARY INTERLOCK
SWITCHES
The primary interlock switch is mounted in the lower position
of the latch hook and the door sensing switch in the second-
ary interlock system is mounted in the upper position of the
latch hook. They are activated by the latch heads on the
door. 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 secondary interlock system
consists of the door sensing switch and 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 second-
ary interlock relay (RY2) and primary interlock 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 (RY2)
and primary interlock switch are in the OFF condition
(contacts open) due to their being nor mally 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 primary interlock switch contacts close.
(On opening the door, each of these switches operate
inversely.)
3. If the door is opened, and the secondary interlock relay
(RY2) and primary 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,
SECONDARY INTERLOCK RELAY (RY2), RE-
LAY (RY1), PRIMARY INTERLOCK SWITCH
AND MONITOR SWITCH FOR PROPER
OPERATION. (REFER 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 dur ing cooking. The tur ntable 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 channeled 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.
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 302OF(150OC) causing the oven to shut down.
NOTE: This is a fuse. It does not reset.
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.
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
Door S ens ing
Switch
MonitorS witch
Switch L eve r
Primary Interlock
Switch
Latch Hea ds
Door