Sharp R-580D Service Manual Download Page 6

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R-580D

OPERATION SEQUENCE

OFF CONDITION

Closing the door activates all door interlock switches
(1st. latch switch, 2nd. 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 noise filter and the control unit.

Figure O-1 on page 28

1. The display shows "SHARP MICRO-WAVE OVEN".
2. To set any programmes or set the clock, you must

first touch the STOP/CLEAR pad.

3. : appears in the display.

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

comes on at this time.

MICROWAVE COOKING CONDITION

HIGH COOKING
Enter a desired cooking time with the touching NUMBER
pad and start the oven with touching START pad.

Function sequence

Figure O-2 on page 28

CONNECTED COMPONENTS

RELAY

Oven lamp, Fan motor, Turntable motor

RY1

Power transformer

RY2

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 channeled 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 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

CONDITION
DURING

DOOR OPEN

SWITCH

CONTACT

COOKING

(NO COOKING)

1st. latch switch

COM-NO

Closed

Open

2nd. latch switch

COM-NO

Closed

Open

Monitor switch

COM-NC

Open

Closed

Stop switch

COM-NO

Closed

Open

The circuits to the power transformer, fan motor and
turntable motor are cut off when the 1st. latch switch,
2nd. latch switch, and stop switch are 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.

MONITOR SWITCH CIRCUIT
The monitor switch is mechanically controlled by

oven door, and monitors the operation of the 1st and
2nd. latch switches.

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

cycle of a cooking program, the 1st. latch switch and
stop switch must open their contacts first.

After that the contacts (COM-NC) of the monitor

switch can be closed, and the contacts of the 2nd.
latch switch can be opened.

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

NC) of the monitor switch must be opened and the
contacts of the 2nd. latch switch must be closed. After
that the contacts of the 1st. latch switch and stop
switch are closed.

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

the1st. latch switch, 2nd. latch switch remain closed.
The fuse M10A will blow, because the monitor switch
is closed and a short circuit is caused.

MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW
COOKING

When the microwave oven is preset for variable cooking
power, 230-240 volts A.C. power is supplied to the power
transformer intermittently within a 32-second time base
through the relay contact which is coupled with the cur-
rent-limiting relay. The following levels of microwave power
are given.

SETTING;

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

to the percentage of microwave power, because
approx. 2 seconds are needed for heating up the
magnetron filament.

SENSOR COOKING CONDITION

Using the SENSOR COOK or SENSOR INSTANT RE-
HEAT function, the foods are cooked or reheated without
figuring time, power level or quantity. When the oven
senses enough steam from the food, it relays the informa-
tion to its microprocessor which will calculate the remaining
cooking time and power level needed for best results.
When the food is cooked, water vapor is developed. The
sensor “senses” the vapor and its resistance increases
gradually. When the resistance reaches the value set
according to the menu, supplementary cooking is started.
The time of supplementary cooking is determined by ex-
periment with each food category and inputted into the LSI.

32 sec. ON

24 sec. ON

18 sec. ON

12 sec. ON

6 sec. ON

8 sec. OFF

14 sec. OFF

20 sec. OFF

26 sec. OFF

HIGH

MEDIUM HIGH

MEDIUM