Sharp Carousel R-995J Руководство по эксплуатации - Страница 10

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R-995J

RIGHT LATCH SWITCH AND LEFT LATCH SWITCH

1. When the oven door is closed, the contacts COM-NO

must be closed.

2. When the oven door is opened, the contacts COM-NO

must be opened.

STOP SWITCH

1. This switch must make a contact when the door is

closed, and open it when the door is opened.

MONITOR SWITCH

The monitor switch is activated (the contacts opened) by

the switch lever L on the latch hook (left) while the door is

closed. The switch is intended to render the oven inopera-

tive by means of blowing the fuse M8A when the contacts

of the right latch switch and the left latch switch fail to open

when the door is opened.

Function

1. When the door is opened, the monitor switch contacts

close (to the ON condition) due to their being normally

closed. At this time the right latch switch ;and the left

latch switch are in the OFF condition (contacts open)

due to their being normally open contact switches.

2. As the door goes to a closed position, the monitor

switch contacts are opened and right latch switch, left

latch switch and stop switch contacts close. (On opening

the door, each of these switches operate inversely.)

3. If the door is opened and the contacts COM-NO of the

right latch switch and left latch switch fail to open, the

fuse M8A blows simultaneously with closing of the

monitor switch contacts.

CAUTION: BEFORE REPLACING A BLOWN FUSE M8A

TEST RIGHT LATCH SWITCH, THE LEFT

LATCH SWITCH, MONITOR SWITCH AND

MONITOR RESISTOR FOR PROPER OP-

ERATION. (REFER TO CHAPTER "TEST

PROCEDURE").

MONITOR

SWITCH

LEFT

LATCH

SWITCH

LATCH

HEADS

Figure D-1. Switches

MONITOR RESISTOR

The monitor resistor prevents the fuse M8A 250V bursting

when the fuse M8A 250V blows due to the operation of the

monitor switch.

ASYMMETRIC RECTIFIER

The asymmetric rectifier is a solid state device that

prevents current flow ins both directions. And it prevents

the temperature rise of the power transformer by blowing

the fuse M8A when the high voltage rectifier is shorted.

FUNCTION OF IMPORTANT COMPONENTS

LATCH HOOK

(LEFT)

STOP

SWITCH

LATCH HOOK

(RIGHT)

RIGHT

LATCH

SWITCH

ASYMMETRIC

RECTIFIER

The rated peak reverse voltage of D1 of the asymmetric

rectifier is 6 KV The rated peak reverse voltage of D2 of the

asymmetric rectifier is 1.7 KV. D1 and D2 of the asymmet-

ric rectifier or high voltage rectifier are shorted when the

each peak reverse voltage goes beyond the each rated

peak reverse voltage. (The process of blowing the fuse

M8A.) .

1. The high voltage rectifier is shorted by any causes

when microwave cooking.

2. The peak reverse voltage of D2 of the rectifier goes

beyond the rated peak reverse voltage 1.7 KV in the

voltagedoubler circuit.

3. D2 of the rectifier is shorted.

4. The large electric currents flow through the high

voltagewinding of the power transformer.

5. The large electric currents beyond 8A flow through the

primary winding of the power transformer.

6. The fuse M8A blows by the large electric currents.

7. The power supply to the power transformer is cut off.

FUSE M8A 250V

1. If the wire harness or electrical components are short-

circuited, this fuse blows to prevent an electric shock or

fire hazard.

2. The fuse also blows when right latch switch and left

latch switch remain closed with the oven door open and

when the monitor switch closes.

3. The fuse M8A also blows when asymmetric rectifier,

H.V. rectifier, H.V. wire harness, H.V. capacitor,

magnetron or secondary winding of power transformer

is shorted.

THERMISTOR

The thermistor is a negative temperature coefficient type.

The temperature in the oven cavity is detected through the

resistance of the thermistor, and then the control unit

causes the heating element relay to operate, thus the

current to the heating element is turned ON/OFF.

TURNTABLE MOTOR

The turntable motor drives the turntable supporting plate

to rotate the turntable.

CONVECTION MOTOR

The convection motor drives the convection fan and

provides the heated air.

FAN MOTOR

The fan motor drives a blade which draws external cool air.

This cool air is directed through the air vanes surrounding

the magnetron and cools the magnetron. This air is chan-

nelled through the oven cavity to remove steam and

vapours given off from the heating foods. It is then ex-

hausted through the exhausting air vents at the oven

cavity.

HIGH VOLTAGE

RECTIFIER