Section IV. HELMET SIGHT ASSEMBLY TEST THEORY

TM 9-4931-363-14&P

Section IV. HELMET SIGHT ASSEMBLY TEST THEORY

c. Refer to step 2 in figure 2-4 and in the helmet sight

2-7. General.

assembly test table. The 28 volts is connected to helmet

sight lamp assembly DS1 as explained in step 1. When S11

The following reference materials are required to

is pressed, contacts 1 and 2 of S11 and wiper 1 and contact

support the helmet sight assembly test theory discussions:

2 of S4-B connect 28 volts dc to energize K2. As S11 is

a. Helmet sight assembly test table from TM

pressed, DS1 should go out as the ground at J1-4 is

removed. Note that when K2 is energized, a ground path is

9-1270-212-14&P

provided to switch S1 in the helmet sight. Without a steel

b. Helmet sight assembly schematic diagram from TM

receptacle attached to the magnet, switch S1 in the helmet

9-1270-212-14&P

sight should be open. If the switch is closed, the reticle will

remain on.

c. Helmet sight assembly test functional diagram (fig.

d. Refer to step 3 in figure 2-4 and in the helmet sight

assembly test table. The 28 volts is connected to helmet

2-8. Helmet Sight Assembly Test Theory.

sight lamp assembly DS1 as explained in step 1. With the

helmet boresight tool connected to the receptacle magnet,

a. To prepare for the helmet sight assembly test

S1 in the helmet sight should be closed, causing the reticle

discussion, refer to the helmet sight assembly checkout

to light. The return path is from J4-4, through J4-6,

procedures in TM 9-1270-212-14&P and mentally perform

through S1, through J4-5, and through K2-1 and -2 to

steps a through f.

ground.

b. Refer to step 1 in figure 2-4 and in the helmet sight

e. Refer to step 4 in figure 2-4 and in the helmet sight

assembly test table. Wiper 1 and contact 2 of S4-A connect

assembly test table. When S10 is pressed, it applies 28 volts

28 volts dc through dropping resistor R13 and through J4-1

dc to J4-7 and a return at J4-8, which causes retract

to helmet sight lamp assembly DS1. The return is

solenoid L1 to energize.

connected through J4-4 and through K1-3 to ground.