FUNCTION OF IMPORTANT COMPONENTS
RIGHT LATCH SWITCH AND LEFT LATCH
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.
STOP SWITCH
1. This switch must make a contact when the door is closed,
and open it when the door is opened.
IVIONITOR SWITCH SW3
The monitor switch is activated (the contacts opened) by the
switch lever L on the latch hook (left) while the door is
closed. The switch is intended to render the oven inopera-
tive by means of blowing the fuse M8A when the contacts
of the right latch switch and the left latch switch fail to
open when the door is opened.
Function
1. When the door is opened, the monitor switch contacts
close (to the ON condition) due to their being normally
closed. At this time the right latch switch :and the left latch
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 opened and right latch switch. left latch
switch and stop switch ccntacts close. (On opening the
dcior. each of these switches operate inversely.)
T if the door is opened and the contacts COM-NO of the
.
:IJ~I latch switch and left latch switch fail to open. the fuse
‘~48.4 si3ws simtiltaneously with closing 3f the monitor
svpr:P co?tarts
I t “L.
C.4L
T/ON: BEFORE REPLACING A BLOWN FUSE M8A
TEST RIGHT LATCH SWITCH. THE LEFT
JxTCi-4 SWITCH, MONITOR SWITCH AND
MONITOR RESISTOR FOR PROPER OPERA-
TION.
(REFER TO CHAPTER “TEST PROCEDURE”}.
t\y!tp 2p
STOP
MONITOR RESISTOR
The monitor resistor prevents the fuse M8A 25OV bursting
when the fuse M8A 250V blows due to the operation of the
monitor switch.
8
ASYMMETRIC RECTIFIER
The asymmetric rectifier is a solid state device that pre-
vents current flow ins both directions. And it prevents
the temperature rise of the power transformer by blow-
ing the fuse M8A when the high voltage rectifier is
shorted.
Dl
/
I
ASYMMETRIC
RECTIFIER
P
HIGH VOLTAGE RECTIFIER
The rated peak reverse voltage of Dl of the asymmetric
rectifier is 6 KV The rated peak reverse voltage of D2 of
the asymmetric rectifier is 1.7 KV. DI and D2 of the
asymmetric rectifier or high voltage rectifier are shorted
when the each peak reverse voltage goes beyond the
each rated peak reverse voltage. (The process of blow-
ing the fuse M8A.) .
1. The high voltage rectifier is shorted by any causes
when microwave cooking.
2. The peak reverse voltage of D2 of the rectifier goes
beyond the rated peak reverse voltage 1.7 KV in the
voltagedoubler circuit.
3. D2 of the rectifier is shorted.
4. The large electric currents flow through the high volt-
agewinding of the power transformer.
5. The large electric currents beyond 8A flow through
the primary winding of the power transformer.
6. The fuse M8A blows by the large electric currents.
7 The power supp y
i .
I to the power transformer is cut off.
FUSE M8A 250V
I.
2.
3.
If the wire harness or electrical components are
short-circuited. this fuse blows to prevent an electric
shock or fire hazard.
The fuse also blows when right latch switch and left
latch switch remain closed with the oven door open
and when the monitor switch closes.
The fuse M8A also blows when asymmetric rectifier,
H.V. rectifier, H.V. wire harness. H.V.capacitor,
magnetron or secondary winding of power trans-
former is shorted.
THERMISTOR
The thermistor is a negative temperature coefficient
type. The temperature in the oven cavity is detected
through the resistance of the thermistor, and then the
control unit causes the heating element relay to oper-
ate, thus the current to the heating element is turned
ON/OFF.
TURNTABLE MOTOR
The turntable motor drives the turntable supporting
plate to rotate the turntable.
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