Chapter 2. THEORY OF OPERATION

TM 9-4931-363-14&P

CHAPTER 2

THEORY OF OPERATION

Section I. GENERAL

2-1. Scope.

a. This chapter provides the theory of operation of the

test set and the theory of tests for the HSS items under

test. Thus, the theory discussions are a composite of test set

theory and item-under-test theory. The following material

provides an understanding of the theory:

(1) Figure 2-1 is a timing diagram for the phase

detector circuit on circuit card A2. Functional diagrams

(figs. 2-2 through 2-12) show test set and adapter cable

connections for each step of each test. The functional

diagram layouts follow the same order as the steps of the

troubleshooting tables in TM 9-1270-212-14&P.

(2) The schematic diagrams of applicable test cables

W3, W4, and W5 (figs. 2-13 through 2-15) are located at the

end of this chapter. The schematic diagram for test cable

W2 (foldout FO-1) is located at the end of this manual.

NOTE

The schematic diagram of the helmet boresight

(3) The schematic diagram of the test set and two

printed circuit cards (foldouts FO-2 through FO-4) are

located at the end of this manual.

b. The theory discussions use test set connector and pin

designations. For example, logic card A10 from the EIA

used in XM128 and logic card A15 from the EIA used in

XM136 are each tested in test set connector J8; therefore,

all connections to and from a logic card in the theory carry

the test set J8 designation.

Figure 2-1. Phase detector timing diagram

2-1