Sharp R-1500 Description And Function Of Components, Door Open Mechanism, Temperature Fuse Mg

R-1500

R-1501

R-1505

R-1506

DESCRIPTION AND FUNCTION OF COMPONENTS

DOOR OPEN MECHANISM

The door is opened by pushing the open button on the control panel, refer to the Figure D-1.

When the open button is pushed, the open button pushes up the open lever, and then the open lever pushes up the latch head. The latch heads are moved upward and released from latch hook. Now the door will open.

Latch heads

	Latch hook
	Door sensing
Door	switch
	Monitor switch
	Open lever
	Primary interlock switch

Figure D-1. Door Open Mechanism

3.If the door is opened, and the secondary interlock relay (RY2) and primary interlock switch contacts fail to open, the monitor fuse blows simultaneously with closing of the monitor switch contacts.

CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE TEST THE DOOR SENSING SWITCH, SECONDARY INTERLOCK RELAY (RY2), RELAY (RY1), PRIMARY INTERLOCK SWITCH AND MONITOR SWITCH FOR PROPER OPERATION. (REFER TO CHAP- TER "TEST PROCEDURE").

NOTE: MONITOR FUSE AND SWITCH ARE REPLACED AS AN ASSEMBLY

TEMPERATURE FUSE (MG)

The temperature fuse located on the fan duct assembly is designed to prevent damage to the magnetron if an over heated condition develops in the tube due to cooling fan failure, obstructed air guide, dirty or blocked air intake, etc. Under normal operation, the temperature fuse remains closed. However, the temperature fuse will open at 302˚F (150˚C) causing the oven to shut down.

NOTE: This is a fuse. It does not reset.

DOOR SENSING AND PRIMARY INTERLOCK SWITCHES

The primary interlock switch is mounted in the lower posi- tion of the latch hook and the door sensing switch in the secondary interlock system is mounted in the upper posi- tion of the latch hook. They are activated by the latch heads on the door. When the door is opened, the switches inter- rupt the circuit to all components. A cook cycle cannot take place until the door is firmly closed thereby activating both interlock switches. The secondary interlock system con- sists of the door sensing switch and secondary interlock relay located on the control circuit board.

MONITOR SWITCH

The monitor switch is activated (the contacts opened) by the latch head on the door while the door is closed. The switch is intended to render the oven inoperative by means of blowing the monitor fuse when the contacts of the second- ary interlock relay (RY2) and primary interlock switch fail to open when the door is opened.

Functions:

1.When the door is opened, the monitor switch contact close (to the ON condition) due to their being normally closed. At this time the secondary interlock relay (RY2) and primary interlock switch are in the OFF condition (contacts open) due to their being normally open contact switches. And the contacts of relay (RY1) are in the ON condition (contacts close).

2.As the door goes to a closed position, the monitor switch contacts are first opened and then the door sensing switch and the primary interlock switch contacts close. (On opening the door, each of these switches operate inversely.)

THERMAL CUT-OUT (HOOD )

This thermal cut-out located on the right base plate flange (turntable motor side). It is designed to automatically turn on the hood fan motor whenever the hot air rising from the conventional range below causes the temperature at the thermal cut-out to rise to 140˚F (60˚C) or higher, thus removing this hot air from around microwave oven. When the temperature around the thermal cut-out drops to 113˚F (45˚C) or lower, the thermal cut-out shuts off the hood fan motor.

THERMAL CUT-OUT (CAVITY )

This thermal cut-out is located on the bottom of the oven cavity. It is designed to prevent damage to the oven unit if the food in the oven catches fire due to overheating pro- duced by improper setting of cooking time or failure of control unit.

Under normal operation, the thermal cut-out remains closed. However, the thermal cut-out will open at 293˚F (145˚C) causing the oven to shut down. The defective thermal cut- out must be replaced with a new one.

TURNTABLE MOTOR

The turntable motor rotates the turntable located on the bottom of the oven cavity, so that the foods on the turntable cook evenly during cooking. Turntable will turn in either direction. The turntable motor can be turned off by touching TURNTABLE ON/OFF pad.

COOLING FAN MOTOR

The cooling 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

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