DOOR OPEN MECHANISM
The door is opened by pushing the open button on the
control panel, refer to the Figure D-l.
When the open button is pushed, the open button pushes
up the switch lever, and then the switch lever pushes up
the the latch head. The latch heads are moved upward and
released from latch hook. Now the door will open.
LATCH dOOK
2ND LATCH
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SWITCH
--. MONITCR
Figure D-l. 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. latch switch and 2nd. latch switch fail to
open, the fuse M8A blows simultaneously with closing
the contacts (COM-NC) of the monitor switch.
CAUTION: BEFORE REPLACING A BLOWN FUSE M8A
TEST THE 1ST. LATCH SWITCH, 2ND.
LATCH SWITCH MONITOR SWITCH AND
MONITOR RESISTOR FOR PROPER OP-
ERATION.
MONITOR RESISTOR R 0.8R 20W
The monitor resistor prevents the fuse M8A bursting when
the fuse M8A blows due to the operation of the monitor
switch.
FUNCTION OF IMPORTANT COMPONENTS
ASYMMETRIC RECTIFIER
The asymmetric rectifier is a solid state device that pre-
vents current flow in both directions. And it prevents the
temperature rise of the power transformer by blowing the
fuse M8A when the high voltage rectifier is shorted.
/
HIGH VOLTAGE RECTIFIER
The rated peak reverse voltage of DI of the asymmetric
rectifier is 6 KV The rated peak reverse voltage of D2 of the
asymmetric rectifier is 1.7 KV. Dl and D2 of the asymmet-
ric rectifier or high voltage rectifier are shorted when the
each peak reverse voltage goes beyond the each rated
peak reverse voltage. (The process of blowing the fuse
MSA.)
1. The high voitage rectifier is shorted by any causes
when microwave cooking.
2. The peak reverse voltage oi Df of the rectifier goes
beyond the rated
peak reverse voltage i .7 KV in the voltage doubler cir-
cuit.
3. D2 of the rectifier is shorted.
4. The large electric currents flow through the high voltage
winding 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 supply to the all electrical parts are cut off.
FUSE M8A
1. The fuse M8A blows when the contacts (COM-NO) of
the 1st. latch switch and 2nd. latch switch remain
closed with the oven door open and when the monitor
switch closes.
2. The fuse M8A also blows when asymmetric rectifier,
H.V. rectifier, H.V. wire harness, H.V.capacitor, magne-
tron or secondary winding of power transformer is
shorted.
3. If the wire harness or electrical components are short-
circuited, this fuse M8A blows to prevent an electric
shock or fire hazard.
THERMAL CUT-OUT TC 145°C (MG)
This thermal cut-out protects the magnetron against over-
heating. If the temperature goes up higher than 145°C
because the fan motor is interrupted, the ventilation open-
ings are blocked, the thermal cut-out will open and the line
voltages to the power transformer will be cut off and the
operation of the magnetron will be stopped.
The defective thermal cut-out must be replaced with new
one.
5
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