CIRCUIT DESCRIPTION
GENERAL DETAILS
• The low voltage transformer supplies the necessary
voltage to the micom controller when power cord is
plugged in.
• When the door is closed, the primary switch is ON, the
secondary switch is ON, and the monitor switch opens
(contact COM and NO).
WHEN SELECTING COOKING POWER
LEVEL AND TIME
• The micom controller memorizes the function you set.
• The time you set appears in the display window.
• Each indicator light turns on to indicate that the stage
has been set.
WHEN TOUCHING THE START PAD
• The coil of the relay is energized by the micom
controller.
• Power input is supplied to the high voltage transformer
through the fuse to the primary switch and relay 2.
• Turntable rotates.
• Cooking time starts counting down.
• 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 high
voltage diode and charging of the high voltage
capacitor.
• The negative 4000 Volts DC is applied to the filament
of the magnetron.
WHEN THE OVEN IS SET AT ANY LEVEL
EXCEPT MAXIMUM.
• The micom controller controls the ON-OFF time of relay
2 by the applied signal to vary the average output
power of microwave oven as POWER LEVEL.
(refer to page 1-1)
WHEN THE DOOR IS OPENED DURING
COOKING
• Both the primary switch and relay 2 are cut off primary
winding voltage of the high voltage transformer.
• ON-OFF of relay 2 is coupled electrically with opening
and closing of the secondary switch.
• When the door is opened, the secondary switch is
opened and when the door is closed, the secondary
switch is closed.
• The cooking time stops counting down.
• Relay stops functioning.
• As the door is opened, if the contact of primary switch
and relay 2 and/or secondary switch fails to open, the
fuse opens due to the large current surge caused by
the monitor switch activation, which in turn stops
magnetron oscillation.
4-4
L
FUSE
TRANS-
FORMER
RELAY 2
MICOM CONTROLLER
SECONDARY
SWITCH
SWITCH
N
MONITOR
SWITCH
PRIMARY
MONITOR
SWITCH
L
FUSE
FORMER
RELAY 2
MICOM CONTROLLER
SECONDARY
SWITCH
PRIMARY
SWITCH
N
• The fan motor rotates and cools the magnetron by
blowing the air (coming from the intake on the
• The air is also directed into the oven to exhaust the
vapor in the oven through the left side.
backplate).
TRANS-
Summary of Contents for NN-ST342M
Page 9: ...SCHEMATIC DIAGRAM 4 3...
Page 29: ...6 2 DOOR PARTS D04 05 S03 D06 01 05 08 D03 D 1 2 3 4 5 6 7 8...
Page 30: ...6 3 CONTROL PANEL PARTS C 05 C18 S03 C01 C55 C 11 15 12 9 10...
Page 31: ...6 4 OVEN CAVITY PARTS 21 25 24 27 26 19 22 64...
Page 32: ...6 5 LATCH BOARD PARTS 28 29 29 30 32...
Page 33: ...INTERIOR PARTS 6 6 34 37 38 39 40 41 42 43 44 45 48...
Page 34: ...6 7 BASE PLATE PARTS 49 50 51 52 54 55 63 58 58 58 58...
Page 40: ......
