Electrical Operation

TM 11-6730-235-35

contacts removes power from the blower motor,

2-3. Electrical Operation

which had been operating even though power had

The electrical operation of the projector involves

been turned off.

the application of power to the convenience outlet

on the projector, the application of power to the

d. If the top plate assembly of the projector is

projection lamp, and the control of the power

opened for maintenance of items in the case

applied to the blower motor in the projector. The

assembly or on the top plate assembly, the

electrical elements involved in these operations are

interlock arm of the case assembly is actuated.

shown schematically in figure 2-2.

When this arm is actuated, the contacts of inter-

lock switch S1 open. Opening these contacts

a. Power is connected to the projector by line

removes power from convenience outlet J1, lamp

plug P1. Whenever the top plate assembly of the

I1, and blower motor B1, regardless of the states of

projector is in the closed position, the contacts of

ON-OFF switch S2 and thermal switch S3.

interlock switch S1 are closed. With interlock

switch S1 contacts closed, power is routed to

convenience outlet J1.

b. When ON-OFF switch S2 is placed in the on

position, power is also applied to projection lamp

I1 and to blower motor B1. As a result, projection

lamp I1 lights and blower motor B1 drives a

cooling fan for the lamp.

c. When the heat produced by the light

radiation from lamp I1 reaches 135°F (57°C), the

contacts of thermal switch S3 close and parallel the

closed contacts of ON-OFF switch S2. When

ON-OFF switch S2 is placed in the off position,

S2 contacts open. The parallel connection provided

by thermal switch S3 contacts remain, however,

until the temperature drops to 131°F (54°C). At

Figure 2-2. Projector, electrical schematic diagram.

that time, the opening of the thermal switch S3

2-3