Daewoo KOR-612L0S, Service Manual

Page: 24 / 55

23
CIRCUIT DESCRIPTION
Refer to the “KOR-612L0S WIRING DIAGRAM” (Fig. 1) on page 22.
MICROWAVE COOKING
TIME COOKING
1. When the food is placed inside the oven and door is closed.
1) The low voltage transformer supplies the necessary voltage to the touch control circuit when the
power cord is plugged in.
2) The contacts of the interlock monitor switch open. This switch creates short circuit to blow 12A
fuse and stop magnetron oscillation when door is opened during operation under abnormal condi-
tion (i.e. the contacts of primary interlock switch do not open the circuit).
3) The contacts of primary interlock switch close the primary circuit.
2. When cooking cycle, power and time are set by touching the function pads and the desired
numerical pads.
1) The function indicating bars are located on the digitron light to indicate that function have been
set.
2) The time you set appears in the display window.
3) The touch control circuit memorizes the cooking program you set.
3. When the start pad is touched.
* The RELAY “1”, “2” are controlled by the touch control circuit.
1) 230VAC is applied to the high voltage transformer through the contacts of RELAY “1”(See Fig. 1)
2) Fan motor starts rotating and cools the magnetron by blowing the air coming from the intake on
the rear plate hold.
3) The oven lamp light the inside of the oven.
4) Indicator light turns on to indicate function operation. Cooking time starts count down.
5) 3.3 Volts AC is generated from the filament winding of the high voltage transformer. This filament
voltage is applied to the magnetron to heat the magnetron filament through two noise preventing
choke coils.
6) A high voltage of 2000 Volts AC is generated in the secondary of high voltage transformer and this
secondary voltage is increased by the action of the diode and the charging of the high voltage
capacitor. This resultant DC voltage is then applied to the anode of the magnetron. As shown in
Fig. 2 the first half cycle of the high voltage produced in the high voltage transformer secondary
charges the high voltage capacitor. Current flow is in the direction of the dotted-line during the sec-
ond half cycle, the voltage produced by the transformer secondary, and the charge of the high
voltage capacitor are combined and applied to the magnetron as shown by the solid line so that
oscillations begin. The disturbance wave generated by the magnetron is prevented by the choke
coils of 3.2µH, filter capacitors of 16pF and the magnetron’s shielded case so that TV and radio
programs are not impaired by noise.