DIRECT SUPPORT (INTERMEDIATE) MAINTENANCE INSTRUCTIONS
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
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
TOOLS AND EQUIPMENT
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.
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.