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 latch board. 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.
(While power control knob is set at “Full Power”)
• The contacts of primary and secondary switch close
the circuit.
• Input Volts AC. is applied to the high voltage
transformer through power control switch as shown by
the solid line.
• Turntable rotates.
• The fan motor rotates and cools the magnetron by
blowing the air (coming from the intake holes on the
baseplate) over the magnetron.
• The air is also directed into the oven to exhaust the
vapor in the oven through the upper plate.
• 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
fail to open, the fuse opens due to the large current
surge caused by the monitor switch activation which in
turn stops magnetron, oscillation.
FUSE
PRIMARY
SWITCH
SECONDARY
SWITCH
MONITOR
SWITCH
MONITOR
RESISTOR
L
N
H.V.T
RELAY
TIMER
SWITCH
POWER
CONTROL
SWITCH
FUSE
PRIMARY
SWITCH
SECONDARY
SWITCH
MONITOR
SWITCH
L
N
H.V.T
RELAY
TIMER
SWITCH
POWER
CONTROL
SWITCH
MONITOR
RESISTOR
Summary of Contents for MS-197H
Page 9: ...SCHEMATIC DIAGRAM 4 3 ...
Page 12: ...6 2 13552A 13213A 13581A 13720D 14970A 14026A 13536A 13352A DOOR PARTS ...
Page 13: ...6 3 24781T 23572A 24510L 250201 24970A 249401 WTP015 26549T CONTROL PANEL PARTS ...
Page 14: ...6 4 33052M 340511 33112U WTT021 34960A 36549S WTP013 33390G 35889A OVEN CAVITY PARTS ...
