Sharp R-480J Operation Sequence, OFF Condition, Microwave Cooking Condition, Variable Cooking

R-480J

OPERATION SEQUENCE

OFF CONDITION

Closing the door activates all door interlock switches (1st. latch switch, 2nd. interlock relay control 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 29

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

2.To set any programs 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 pads and start the oven with touching START pad.

Function sequence

Figure O-2 on page 29

CONNECTED COMPONENTS	RELAY
Oven lamp, Fan motor, Turntable motor	RY1
Power transformer	RY2

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 1st. latch switch and 2nd. interlock relay.

6-1 When the oven door is opened during or after the cycle of a cooking program, the 1st. latch switch and 2nd. interlock relay control switch must open their contacts first. After that the contacts (COM-NC) of the monitor switch can be closed.

6-2. When the oven door is closed, the contacts (COM- NC) of the monitor switch must be opened first. After that the contacts of the 1st. latch switch and 2nd. interlock relay control switch are closed.

6-3. When the oven door is opened and the contacts of the 1st. latch switch and 2nd. interlock relay remain closed. The fuse F10A will blow, because the monitor switch is closed and a short circuit is caused.

VARIABLE 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 relay (RY2). The following levels of microwave power are given.

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

SETTING;

32 sec. ON

HIGH

	24 sec. ON	8 sec. OFF
MEDIUM HIGH
	18 sec. ON	14 sec. OFF
MEDIUM
	12 sec. ON	20 sec. OFF
MEDIUM LOW
	6 sec. ON	26 sec. OFF
LOW

Approx. 70%

Approx. 50%

Approx. 30%

Approx. 10%

	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
	(off condition)º. 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. interlock relay
control switch	COM-NO	Closed	Open
Monitor switch	COM-NC	Open	Closed

The circuits to the power transformer, fan motor and turntable motor are cut off when the 1st. latch switch and 2nd. interlock relay control switch are made open. The oven lamp remains on even if the oven door is opened after the cooking cycle has been interrupted,

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.

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.

An example of how sensor works:

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