Daewoo KOR-3000 Service Manual download pdf (Page 28)

CIRCUIT DESCRIPTION

Refer to the “WIRING DIAGRAM” (Fig. 1) on page 25.

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 15A fuse and stop magnetron oscillation when door is opened during

operation under abnormal condition (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) 220VAC is applied to the high voltage transformer through the contacts of RELAY “1”.

2) Fan motor starts rotating and cools the magnetron by blowing the air coming form 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 prventing choke coils.

6) A high voltage of 2000 Volts AC is generated in the secondary of high voltage transformer and this sec-

ondary 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 second half cycle, the voltage produced by the

transformer secondary, and the charge of the high voltage capacitor are combined and applied to the mag-

netron as shown by the solid line so that oscillations begin. The disturbance wave generated by the

mangetron is prevented by the choke coils of 3.2µH, filter capacitor of 16pF and the magnetron’s shielded

case so that TV and radio programs are not impaired by noise.

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Daewoo KOR-3000 Service Manual Page 28