13
R-1750
R-1751
R-1752
R-1754
DESCRIPTION AND FUNCTION OF COMPONENTS
DOOR OPEN MECHANISM
The door is opened by pulling the door handle, refer to the
Figure D-1.
LOCK SWITCH AND MONITOR SWITCH FOR
PROPER OPERATION. (REFER TO CHAP-
TER "TEST PROCEDURE").
NOTE: MONITOR FUSE AND SWITCH ARE REPLACED
AS AN ASSEMBLY
TEMPERATURE FUSE (MG)
The temperature fuse located near the waveguide 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 temperature fuse remains
closed. However, the temperature fuse will open at 302˚F
(150˚C) causing the oven to shut down.
THERMAL CUT-OUT (HOOD )
This thermal cut-out located on the right base plate. It is
designed to automatically turn on the hood fan motor
whenever the hot air rising from the conventional range
below causes the temperature at the thermal cut-out to rise
to 140˚F (60˚C) or higher, thus removing this hot air from
around microwave oven. When the temperature around the
thermal cut-out drops to 113˚F (45˚C) or lower, the thermal
cut-out shuts off the hood fan motor.
THERMAL CUT-OUT (OVEN )
This thermal cut-out is located on the top of the oven cavity.
It is designed to prevent damage to the oven unit if the food
in the oven catches fire due to overheating produced by
improper setting of cooking time or failure of control unit.
Under normal operation, the thermal cut-out remains closed.
However, the thermal cut-out will open at 293˚F (145˚C)
causing the oven to shut down.
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. Turntable will turn in either
direction. The turntable motor can be turned off by touching
TURNTABLE ON/OFF pad.
COOLING FAN MOTOR
The cooling fan motor drives a blade which draws external
cool air. This cool air is directed through the air vanes
surrounding 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.
HOOD FAN MOTOR
The hood fan motor is a two-speed, single-phase, double
pole induction type, requiring a hood fan capacitor. It is
located outside the upper rear part of the oven cavity, is to
remove, from around the oven, hot air rising from the
conventional electric or gas range over which it is installed.
This air is then expelled either vertically or horizontally
through the customer supplied duct system, or discharged
back into the kitchen.
Figure D-1. Door Open Mechanism
STOP, PRIMARY INTERLOCK AND SECONDARY
INTERLOCK SWITCHES
The secondary interlock switch is mounted in the lower
position of the latch hook and the stop switch is mounted in
the upper position of the latch hook. The primary interlock
switch is also 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 circuit to all compo-
nents. A cook cycle cannot take place until the door is firmly
closed thereby activating both interlock switches.
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
interlock switch and secondary 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 primary interlock switch and
secondary interlock switch are in the OFF condition
(contacts open) due to their being normally open contact
switches. And the contacts of relay (RY1) are in the ON
condition (contacts close).
2. As the door goes to a closed position, the monitor switch
contacts are first opened and the stop switch contacts
close, and then the primary interlock 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 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 STOP SWITCH, PRIMARY
INTERLOCK SWITCH, SECONDARY INTER-
Secondary
Interlock
Switch
Monitor
Switch
Stop
Switch
Monitor
Fuse
Primary
Interlock
Switch
Latch
Hook
Door
Latch
Heads
