R-450C
5
Figure D-1. Door Open Mechanism
1ST. LATCH SWITCH, 2ND. LATCH SWITCH AND
STOP SWITCH
1. When the oven door is closed, the contacts (COM - NO)
must be closed.
2. When the oven door is opened, the contacts (COM -
NO) must be opened.
MONITOR SWITCH
1. When the oven door is closed, the contacts (COM- NC)
must be opened.
2. When the oven door is opened, the contacts (COM-
NC) must be closed.
3. If the oven door is opened and the contacts (COM- NO)
of the 1st. and 2nd. latch switches fail to open, the fuse
(M10A) blows simultaneously with closing the contacts
(COM-NC) of the monitor switch.
CAUTION: BEFORE REPLACING A BLOWN FUSE
(M10A) TEST THE 1ST. AND 2ND. LATCH
SWITCHES, MONITOR SWITCH AND MONI-
TOR RESISTOR FOR PROPER OPERA-
TION. (REFER TO CHAPTER “TEST PRO-
CEDURE”.)
MONITOR RESISTOR (0.8
Ω
20W)
The monitor resistor prevents the fuse (M10A) bursting
when the fuse blows due to the operation of the monitor
switch.
THERMAL CUT-OUT 145˚C (OVEN)
The thermal cut-out located on the top of the oven cavity
is designed to prevent damage to the oven if the foods in
the oven catch fire due to over heating produced by
improper setting of cook time or failure of control unit.
Under normal operation, the oven thermal cut-out remains
closed. However, when abnormally high temperature is
reached within the oven cavity, the oven thermal cut-out
FUNCTION OF IMPORTANT COMPONENTS
DOOR OPEN MECHANISM
The door can be opened by pushing the door open button
on the control panel. When the door open button is
pushed, the latch lever is moved upward, operating the
latch heads. The latch head is moved upward, and re-
leased from the latch hook. Now, the door can be opened.
will open at 145˚C, causing the oven to shut down. The
defective thermal cut-out must be replaced with new one.
FUSE (M10A)
1. If the wire harness or electrical components are short-
circuited, this fuse blows to prevent an electric shock or
fire hazard.
2. The fuse also blows when 1st. and 2nd. latch switches
remains closed with the oven door open and when the
monitor switch closes.
HIGH VOLTAGE FUSE 0.75A
The high voltage fuse blows when the high voltage rectifier
or magnetron is shorted.
TEMPERATURE FUSE 150˚C (MG)
This fuse protects the magnetron against overheating. If
the temperature goes up higher than 150˚C because the
fan motor is interrupted, the air inlet duct is blocked or the
ventilation openings are obstructed, the fuse blows and
puts the oven out of operation.
The defective fuse must be replaced with new rated one.
TURNTABLE MOTOR
The turntable motor drives the turntable roller assembly to
rotate the turntable.
FAN MOTOR
The 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 chan-
nelled through the oven cavity to remove steam and
vapours given off from the heating foods. It is then ex-
hausted through the exhausting air vents at the oven
cavity.
NOISE FILTER
The noise filter prevents the radio frequency interference
that might flow back in the power circuit.
Latch Hook
2nd. Latch
Switch
Monitor
Switch
Stop
Switch
Switch
Lever
Latch
Heads
Door
1st. Latch
Switch
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