Description And Function Of Components - Sharp R-402JW-T Service Manual

R402JWT

[3] DESCRIPTION AND FUNCTION OF COMPONENTS

1. DOOR OPEN MECHANISM
The door is opened by pushing the open button on the control panel,
refer to the Figure D-1. When the open button is pushed, the open but-
ton 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.
Door
Switch Lever
Figure D-1. Door Open Mechanism.
2. 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 secondary interlock sys-
tem is mounted in the upper position of the latch hook. They are acti-
vated 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 there by activat-
ing both interlock switches. The secondary interlock system consists
of the door sensing switch and secondary interlock relay located on
the control circuit board.
3. 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 secondary 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 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 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 MONITORFUSE TEST
THE DOOR SENSING SWITCH, SECONDARY INTER-
LOCK RELAY (RY2), RE-LAY (RY1), PRIMARY INTER-
LOCK SWITCH AND MONITOR SWITCH FOR PROPER
OPERATION. (REFER TO CHAPTER "TEST PROCE-
DURE").
NOTE: MONITOR FUSE AND MONITOR SWITCH ARE REPLACED
AS AN ASSEMBLY.
Latch Heads
Door Sensing
Switch
Monitor Switch
Primary Interlock
Switch
4. 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.
5. 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 magne-
tron 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.
6. OVEN THERMAL CUT-OUT
The thermal cut-out, 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 thermal cut-
out will open. 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
293°F(145°C), causing the oven to shut down.
7. MAGNETRON TEMPERATURE FUSE
The magnetron temperature fuse located near the magnetron is
designed to prevent damage to the magnetron if an over heated condi-
tion 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 abnor-
mally high temperatures are reached within the magnetron, the mag-
netron temperature fuse will open at 302°F(150°C) causing the oven
to shut down.
NOTE: This is a fuse. It does not reset.
8. MONITOR FUSE
1) The monitor fuse blows when the contacts (COM-NO) of the pri-
mary 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.
9. NOISE FILER
The noise filter prevents the radio frequency interference that might
flow back in the power circuit.
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