NN-GM231WZPE - Panasonic Home Appliance Service Manual (repair manual). Page 10

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4-4
CIRCUIT DESCRIPTION
• As the door is closed, the contact of MONITOR
SWITCH opens. This switch creates the short circuit to
blow fuse during operation under abnormal condition.
(ie, should the contacts of primary and secondary
switch fail to open the circuit)
• The latches are secured by Door hook. The oven light
turns on while the oven is in operation.
WHEN MICROWAVE POWER LEVEL
AND COOKING TIME SET
• The contacts of the timer switch changes to ON
position when the timer knob is rotated.
• The contacts of primary and secondary switch close
the circuit.
• Input Volts AC.
transformer and the microwave oven begin to operate.  
• Turntable rotates.
• The fan motor rotates and cools the magnetron by
blowing the air (coming from the intake holes on the
backplate) over the magnetron.
• The air is also directed into the oven to exhaust the
vapor in the oven through the left side.
• Timer starts rotating.
• 3.2 volts AC is generated from the filament winding of
the high voltage transformer. This 3.2 volts is applied
to the magnetron to heat the magnetron filament
through two noise preventing choke coils.
A high voltage of approximately 2100 volts AC is
generated in the secondary of the high voltage
transformer which is increased by the action of the
diode and charging of the high voltage capacitor.
The negative DC voltage is then applied to the filament
of the magnetron.
WHEN THE DOOR IS OPENED DURING
COOKING
• Both primary switch and secondary switch open to cut
off the primary winding voltage to the high voltage
transformer to stop microwave oscillation.
• Timer, turntable and fan motor stop.
• As the door is opened, if the contact of primary switch
and secondary switch fail to open, the fuse opens due
to the large current surge caused by the monitor switch
activation which in turn stops magnetron, oscillation.
WHEN THE GRILL COOKING FUNCTION
SELECTED
• The contacts of the timer switch change to ON
position.
• 
• Input volts AC is applied to the grill heater through
thermostat-grill as shown.
• The fan motor and turntable rotates.
 
 Electricty apply to the high voltage
 
connect the circuit
the low acting relay assy works and
s
.
.
)
(
Set the power control knob  at  “       ”  The contacts
       
of SW1 COM1and NO1  connected.
 
.
• 
)
(
Set the power control knob  at Max, The contacts
       
of SW1 COM1and NC1  connected.
 
.
NC1
NO1
COM1
COM1
NO1
NC1
SW1
SECONDARY
COM   NO
HIGH   VOLTAGE
TRANSFORMER
PRIMARY SWITCH
COM 
NO
MONITOR
SWITCH
COM
NC
TIMER
SLOW ACTING
RELAY ASS'Y
TIME S/W
SW1
FILTER
FUSH
L
N
GE
GE
NC1
NO1
COM1
SECONDARY
COM   NO
HIGH   VOLTAGE
TRANSFORMER
PRIMARY  SWITCH
COM 
NO
MONITOR
SWITCH
COM
NC
TIMER
SLOW ACTING
RELAY ASS'Y
TIME S/W
SW1
FILTER
FUSH
L
N
GE
GE
FILTER
FUSH
L
N
GE
GE
SECONDARY
COM   NO
MONITOR
SWITCH
COM
NC
TIMER
TIME S/W
SW2
NO2
COM2
H
E
A
TE
R
    SWITCH
   SWITCH
      SWITCH
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