CHAPTER 7 DIRECT SUPPORT (INTERMEDIATE) MAINTENANCE INSTRUCTIONS

CHAPTER 7

DIRECT SUPPORT (INTERMEDIATE) MAINTENANCE INSTRUCTIONS

Section I.

GENERAL

7-1. Introduction

traced first to a functional unit and then to a

defective module. The following is a list of four logical

This chapter provides the information necessary

steps to follow in order to troubleshoot the equip-

to maintain the processor and receiver at the direct

ment effectively and efficiently.

support (intermediate) maintenance level. These

a. History of Equipment. T h e r e p a i r m a n c a n

instructions are intended to assist the maintenance

obtain helpful information by questioning organiza-

technician in determining whether the equipment is

tional maintenance personnel, by reading the com-

operating properly, and if not, to localize the

plaint notice attached to the equipment, and by

malfunction to the level assigned by the Mainte-

reading the equipment log. The more information

nance Allocation Chart (MAC). The maintenance

the repairman can gather, the more accurate his

information in this chapter includes symptom

diagnosis will be and the sooner the trouble can be

analysis procedures and performance test proce-

located and repairs made.

dures. The order of presentation of this maintenance

b. Preliminary Examination. A preliminary ex-

information is arranged in a sequence which is

amination will help in gathering evidence that may

logical in terms of specific maintenance steps

lead to the location of the defect. Symptoms may be

required to maintain the processor and receiver at

obtained by observing the equipment for the

the direct support (intermediate) maintenance level.

following: inadequate surveillance coverage, ab-

a. Detecting faulty operation. The performance

normal nuisance alarms, discolored components or

test (para 7-11) is provided for use in determining

the presence of smoke by smelling to detect the odor

minimum equipment performance requirements.

of burned insulation and parts.

b. Locating Trouble. A troubleshooting chart is

c. Sectionalization. Sectionalization of trouble

provided to aid in locating trouble in a minimum

consists of tracing the trouble to the functional PC

amount of time. The troubleshooting chart (para 7-8)

board responsible for the abnormal performance.

is designed to enable the repairman to locate trouble

Use the information obtained from the procedures

based on indications obtained while the processor

given in a and b above and the troubleshooting chart

and receiver(s) are operating.

as a quick check in sectionalizing the trouble.

c. Checking Serviceability. Direct support (in-

Perform each step (or applicable steps) in the

termediate) testing procedures designed to check the

troubleshooting chart to sectionalize the trouble to a

serviceability of repaired items of equipment are

PC board.

included in Section V. The test procedure is

d. Testing After Repairs. After a faulty PC board

presented in tabular format.

is located and replaced, the equipment may not be

7-2. Troubleshooting Techniques.

free of faults. Some other fault (which has not been

To be effective, troubleshooting must be systema-

detected and corrected) may have caused the failure

of the part that has been replaced, or the repairman

tic. It is seldom possible to observe a symptom of

trouble and immediately diagnose the cause. Usu-

may have inadvertently caused a trouble. After a PC

ally, it will be necessary to perform a sequence of

board has been replaced, the equipment should be

operational checks, observations, and measure-

given an overall performance test (para 7-11) and the

ments before the cause of a trouble is revealed. If the

results compared with the performance require-

ments of the equipment.

proper sequence is followed, the trouble will be

Section II.

TOOLS AND EQUIPMENT

7-3. Tools.

7-1) required for direct support (intermediate)

The tools required for direct support (inter-

Maintenance Allocation Chart (MAC). Equivalent

mediate) maintenance are contained in tool kit

instruments may be used unless otherwise stated.

TK-105/G.

The information provided in these tables is not to be

used as a basis for requisitioning. For requisitioning

7-4. Test Equipment,

test equipment and repair parts, refer to Repair

This section provides a list of test equipment (table

Parts and Special Tools List (RPSTL), Appendix C.

7-1