TM 11591522613
Section II. TROUBLESHOOTING AND MAINTENANCE
with the normally expected indications called
6-5. Direct Support Troubleshooting
out in the procedures provide good operational
tests.
Troubleshooting at direct support level includes
all the techniques outlined for operator's and
(3) Troubleshooting table. The trouble-
organizational maintenance level and any special
or additional techniques required to isolate a
shooting table 6-1 lists symptoms of common
defective part. This usually requires removal of
trouble and gives the corrective measures or
the unit from the vehicle to a shop area where
references. The table cannot include all trouble
bench testing can be conducted.
symptoms that may occur; therefore, the techni-
cian should use this table as a guide in analyzing
symptoms that may not be listed.
a. General. The first step in servicing a
defective F-1461/VRC is to sectionalize the
(4) Component locations. Figures 6-1,
fault. Sectionalization means tracing the fault
to the input or output portion of the unit. The
F-1461/VRC.
second step is to localize the fault. Localization
means tracing the fault to a defective circuit re-
6-6. Troubleshooting Table
sponsible for the condition. Some faults, such
as burned-out components, arcing, and shorted
wiring; can often be located by sight, smell and
troubles within the various circuits of the unit.
sound. The majority of faults however, must be
Refer to figure 6-3 for parts location. Refer to
isolated by checking voltages and resistances.
the overall schematic diagram (fig. 5-1) to iden-
b. Sectionalization and Localization. The
tify circuit components. Depending on the na-
tests given in (1) and (2) below will reduce un-
ture of the operational symptoms, one or more
necessary work and aid in tracing trouble in a
of the localizing procedures will be necessary.
defective F-1461/VRC. The F-1461/VRC is a
When the trouble has been localized to a par-
single unit and is theoretically divided into sev-
ticular circuit use voltage and resistance meas-
eral sections for convenience in troubleshooting
urements to isolate the trouble to a particular
as power distribution wiring, power indicator
part.
circuit and signal distribution wiring.
d. Use of Troubleshooting Table 6-3.
When an abnormal symptom is observed in the
(1) Visual inspection. The purpose of
visual inspection is to locate faults without
equipment, look for a description of the symp-
testing or measuring circuits. All components
tom in the malfunction column, and perform the
should be observed and an attempt made to
corrective action given in corrective action col-
sectionalize and localize the fault to a particular
umn.
part.
e. Conditions for Test. All checks outlined
(2) Operational test. Use an opera-
in the troubleshooting table 6-3 are to be con-
tional test to identify the general location of
ducted with the F-1461/VRC and under power
trouble. In many instances, the test will help in
and operating.
determining the exact nature of the fault. The
operational procedure given in paragraph 3-3,
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