Sharp Carousel R-995J Manual de serviço - Página 6

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Também para Sharp Carousel R-995J: Manual de operação (48 páginas)

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R-995J

OFF CONDITION

Closing the door activates all door interlock switches

(Right latch switch, Left latch switch and stop switch.)

IMPORTANT

When the oven door is closed, the monitor switch contacts

COM-NC must be open.

When the microwave oven is plugged in a wall outlet, rated

voltage is supplied to the point A9 + common terminal of

relay RY1 in the control unit.

Figure O-1 on page 35

1. The display shows "SHARP", "MICRO-", "WAVE" and

"OVEN".

2. To set any programmes or set the clock, you must first

touch the STOP/CLEAR key.

3. " : " appears in the display and the time counts up

every minute.

NOTE: When the oven door is opened, the oven lamp

comes on at this time.

MICROWAVE COOKING CONDITION

HIGH COOKING

Select microwave cooking and power level by pressing the

POWER LEVEL pad and enter desired cooking time by

pressing NUMBER pads. When the START pad is touched,

the following operations occur:

Function sequence Figure O-2 on page 35

CONNECTED COMPONENTS

Oven lamp, Turntable motor (Power transformer)

Power transformer

Fan motor

1. Rated voltage is supplied to the primary winding of the

power transformer. The voltage is converted to about

3.3 volts A.C. output on the filament winding and high

voltage of approximately 2000 volts A.C. on the

secondary winding.

2. The filament winding voltage (3.3 volts) heats the

magnetron filament and the high voltage (2000 volts) is

sent to the voltage doubling circuit, where it is doubled

to negative voltage of approximately 4000 volts D.C..

3. The 2450 MHz microwave energy produced in the

magnetron generates a wave length of 12.24 cm. This

energy is channelled through the waveguide (transport

channel) into the oven cavity, where the food is placed

to be cooked.

4. When the cooking time is up, a signal tone is heard and

the relays (RY1+RY2+RY6) go back to their home

position. The circuits to the oven lamp, power

transformer, fan motor and turntable motor are cut off.

5. When the door is opened during a cook cycle, the

switches come to the following condition.

Switch

Contact

Right Latch Switch

COM-NO

Monitor Switch

COM-NC

Left Latch Switch

COM-NO

Stop Switch

COM-NO

OPERATION SEQUENCE

RELAY

RY1

RY2

RY6

Condition

During

Oven Door

Cooking

Open(No cooking)

Closed

Open

Closed

Open

Closed

Open

The circuits to the power transformer and turntable

motor are cut off when the right latch switch and left

latch switch are made open. The fan motor is cut off

when the stop switch is made open.

The oven lamp remains on even if the oven door is

opened after the cooking cycle has been interrupted,

because the relay (RY1) stays closed. Shown in the

display is the remaining time.

6. MONITOR SWITCH CIRCUIT

The monitor switch is mechanically controlled by

oven door, and monitors the operation of the right latch

switch and left latch switch.

6-1. When the oven door is opened during or after the

cycle of a cooking program, the contacts (COM-NC)

of the monitor switch must be closed and the contacts

(COM-NO) of the right latch switch, left latch switch

and stop switch must be opened at the same time.

6-2. When the oven door is closed, the contacts (COM-

NC) of the monitor switch must be opened and the

contacts (COM-NO) of the right latch switch, left latch

switch and stop switch must be closed at the same

time.

6-3. When the oven door is opened and the contacts of the

right latch switch and the left latch switch remain

closed, the fuse M8A will blow, because the monitor

switch and relay (RY1) are closed and a short circuit

is caused.

MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW

COOKING

When the microwave oven is preset for variable cooking

power, rated voltage is supplied to the power transformer

intermittently within a 32-second time base through the

relay contact which is coupled with the current-limiting

relay RY2. The following levels of microwave power are

given.

SETTING

32 sec. ON

HIGH

24 sec. ON

MEDIUM HIGH

18 sec. ON

MEDIUM

12 sec. ON

MEDIUM LOW

6 sec. ON

LOW

NOTE: The ON/OFF time ratio does not exactly correspond

to the percentage of microwave power, because

approx. 3 seconds are needed for heating up the

magnetron filament.

CONVECTION COOKING CONDITION

PREHEATING CONDITION

Press the PREHEAT pad and then select preheating

temperature by pressing the temperature pad. When the

START pad is touched, the following operations occur:

1. The coil of shut-off relays RY1+RY5+RY6 are

energized, the oven lamp, cooling fan motor, turntable

motor and convection motor are turned on.

8 sec. OFF

Approx. 70%

14 sec. OFF

Approx. 50%

20 sec. OFF

Approx. 30%

26 sec. OFF

Approx. 10%