Sharp R-210A Operation Sequence, Off Condition, Microwave Cooking Condition, Figure O-1on page

R-210A

OPERATION SEQUENCE

OFF CONDITION

1.When the timer knob is at " 0 ", the oven is OFF condition.

2.Closing the oven door activates the 1st latch switch, the 2nd latch switch and monitor switch.

IMPORTANT:

When the oven door is closed, the contacts COM-NC of the monitor switch must be open.

Figure O-1 on page 20

MICROWAVE COOKING CONDITION

HIGH COOKING

Set the variable cooking control to HIGH and then set the timer.

7-1. When the oven door is opened during or after the cycle of a cooking program, the 1st latch switch and 2nd latch switch must open their (COM-NO) contacts first. After that the contacts (COM-NC) of the monitor switch can be closed.

7-2. When the oven door is closed. The contacts (COM- NC) of the monitor switch must be opened and the contacts (COM-NO) of the 2nd latch switch and the 1st latch switch must be closed.

7-3. When the oven door is opened and the (COM-NO) contacts of the 1st latch switch and the contacts (COM-NO) of the 2nd latch switch remain closed, the fuse 13A will blow, the monitor switch is closed and a short circuit is caused.

Function sequence

Figure O-2 on page 20

1. Following components are energized.

Power transformer	H.V. capacitor	Timer motor
Magnetron	H.V. rectifier	Fan motor
H. V. fuse	Turntable motor	Oven lamp

2.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 sec- ondary winding.

3.The filament winding voltage (3.3 volts) heats the magnetron filament and the high voltage (2000 volts) is sent to the voltagedoubling circuit, where it is doubled to negative voltage of approximately 4000 volts D.C..

4.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.

5.When the cooking time is up, the timer returns to "0", the bell rings and the contacts of the timer are opened. Then following components are turned off.

Power transformer	Magnetron	Timer motor
Turntable motor	H.V. capacitor	Fan motor
H. V. fuse	H.V. rectifier	Oven lamp

6.When the oven door is opened during a cooking cycle, the switches come to the following positions and they are common to the other cooking conditions too.

Switch	Contact	Condition
		During	Oven Door
		Cooking	Open(No cooking)
1st latch Switch	COM-NO	Closed	Opened
Monitor Switch	COM-NC	Opened	Closed
2nd latch switch	COM-NO	Closed	Opened

The circuit to the power transformer, turntable motor, timer motor, fan motor and oven lamp are cut off when the COM-NO contacts of the 2nd latch switch and 1st latch switch are made open. The timer stops to indicate how much cooking time remains.

7.MONITOR SWITCH CIRCUIT

The monitor switch is mechanically controlled by the oven door, and monitors the operation of the 1st latch switch and 2nd latch switch.

MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW COOKING

When the microwave oven is preset for variable cooking power, the rated voltage is supplied to the power trans- former intermittently within a 30-second time base through the vari switch. The following levels of microwave power are given.

SETTING	30 sec. ON
HIGH				Approx. 100%
	23.2 sec. ON		6.8 sec. OFF
MEDIUM HIGH				Approx. 70%
	16.5 sec. ON		13.5 sec. OFF
MEDIUM				Approx. 50%
		9.8 sec. ON 20.2 sec. OFF
MEDIUM LOW				Approx. 30%
	5.0 sec. ON		25 sec. OFF
LOW				Approx. 10%

Note: The ON/OFF time ratio does not exactly corre- spond to the percentage of microwave power, because approx. 2 seconds are needed for heat- ing up the magnetron filament.

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