Section II. DESCRIPTION AND DATA

TM 9-4931-363-14&P

Section II. DESCRIPTION AND DATA

test-set-container storage compartments. The test set

1-8. General (fig. 1-1).

container is discussed further in paragraph 1-10 and the test

set chassis assembly, in paragraph 1-11.

a. The test set is used during alignment, boresighting,

and test of a model XM12801- a model XM136 helmet sight

s u b s y s t e m (HSS); HSS XM128 is used in an

1-10. Test Set Container.

AH-1Q/AH-1S(Mod) Cobra Helicopter and HSS XM136, in

an AH-1S Cobra Helicopter. As shown in figure 1-1, the test

All other test set items are stored in the test set

set is made up of a test set subassembly, a linkage

container. Except for the test set chassis assembly, which is

orientation device (LOD), a helmet boresight tool, a circuit

screw-mounted in the bottom part of the container, the

card extractor, a connector shorting assembly, and four

other test set items are stored in the top part (the lid) of

cable assemblies; these items are discussed in detail in

the container. (Figure 1-1 shows the container open and

paragraphs 1-9 through 1-16.

indicates the storage compartments in the container lid;

figure 1-2 shows the closed container). The container is

b. As covered in detailed procedures in TM

aluminum and is equipped with carrying handles, four clasp

9-1270-212-14&P, the test set is used not only for

fasteners to secure the lid to the bottom section, and

alignment and bolesighting of the HSS but also for

slip-out hinges to permit removal of the lid during

complete electrical testing, isolating and verifying

operation. A seal between the lid and the bottom section

equipment failures that are detected by the built-in-test

insures that the container is airtight when the two sections

(BIT) circuits in the HSS EIA. The test set is used to test

are closed and secured. An air-bleed valve on the side of the

the EIA and the two linkages as a system or us separate

container is depressed to equalize the container internal

items, as well as the helmet sight assembly. It can also be

pressure and the external pressure. This valve must be

used to test individual subassemblies of the EIA after they

depressed before an attempt is made to open the container.

are removed from the EIA; separate tests are provided in

TM 9-1270-212-14&P for buffer amplifier modules A1

1-11. Test Set Chassis Assembly.

through A8 and for circuit card assemblies A9 thlough A13

and A15. The only EIA subassembly that cannot be tested

The test set chassis assembly, mounted in the bottom of

as a separate item is azimuth bias circuit card assembly A14

the test set container (fig. 1-1), has an aluminum control

in the EIA for XM136; this circuit card assembly does not

panel on which are mounted all the controls, indicators,

exist in the EIA for XM128.

and connectors. Inside the chassis are the other electrical

components, including the two circuit card assemblies, A2

NOTE

and A12, which are mounted on brackets secured to the

back of the control panel.

In an EIA from XM128, the logic circuit card

assembly has a designation of A10 versus a

1-12. Linkage Orientation Device (fig. 3-2).

designation of A15 in an EIA from XM136.

a. The LOD is used to align the gunner and pilot linkage

assemblies. The LOD consists of a leveling base to which is

1-9. Test Set Subassembly.

attached a bubble level assembly, a bubble level reflector, a

rail clamp base assembly, an alignment pin, a magnet, a

The test set subassembly consists of two main items,

magnet adjustment device, and a borescope angle bracket.

which are the test set chassis assembly and the test set

container, and two plates, which are the test set instruction

b. The bubble level assembly is used to check the

plate and the test set identification plate. The test set

alignment of the linkage rails after the level assembly has

chassis assembly is mounted in the bottom part of the test

been properly adjusted on the telescopic sighting unit

set container, as shown in figure 1-1, but may be removed

(TSU) boresight device. The bubble level reflector enables

and mounted in an electrical-equipment rack. The test set

the operator to check the bubble level from an angle. The

identification plate is mounted on the top (front panel) of

rail clamp base assembly has deep parallel grooves in the

the test set chassis assembly. The test set instruction plate,

base surface that are designed to fit up against the linkage

which states the part numbers of the HSS items which can

be tested with the test set, is mounted on the cover for the

1-2