TM 11-6720-242-35
CHAPTER 3
DIRECT SUPPORT MAINTENANCE
Section I. TROUBLESHOOTING
WARNING
(2) Sectionalization check. After a trouble has
Be
extremely
careful
when
been sectionalized (traced to a component or
troubleshooting and repairing the
assembly), perform the procedures that will localize it to
camera. Power sources of 115 vac,
a system and then isolate it to a part or assembly.
400 hz and 28 vdc are present
(3) Visual inspection. Frequently, a fault may
internally for camera operation. Use
be identified by visual observation alone and in such
insulated test probes when making
case no further localization is required. However,
voltage measurements and always
mechanical faults, such as defective clutches, springs,
disconnect the power sources from
precision fits and spacing, having prescribed conditions,
the equipment before handling
require types of checks applicable to them.
internal parts.
(4) Localizing troubles. One or more
3-1. Troubleshooting Information
localizing procedures may be necessary, depending on
a. General
Troubleshooting.
General
the nature of the symptoms. When the procedure results
troubleshooting at direct support (DS), general support
in localizing trouble to a particular section, use the
(GS) and depot includes the procedures and techniques
designated test procedures to isolate the trouble to a
designated for each lower category of maintenance and
particular assembly or part.
the added special techniques at each category for the
isolation of a defective part.
The systematic
troubleshooting procedures which begin with the
(5) Troubleshooting charts. Troubleshooting
operational and sectionalization checks performed at the
charts aid in localizing trouble to an assembly or part.
organizational level, must be supplemented where
needed by further localization and isolation techniques
(6) Signal substitution. Signal substitution
applicable to the higher category of maintenance being
permits the checking of an assembly by the use of
performed. At organizational level, tests are performed
special test sets which enable applicable signals to be
with the use of Test Set, Camera LS-86A and with the
connected to the various circuits of the assembly to
camera components connected to each other and in
verify their normal response.
operation (TM 11-6720-24212). At the higher category of
maintenance, troubleshooting is usually confined to a
(7) Isolation. Following the isolation of a
single component or assembly and performed with a
trouble to a circuit, the parts comprising the circuit are
bench test setup.
checked to determine their operational status. As the
b. Organization of Troubleshooting Procedures.
equipment is transistorized, all precautions must be
(1) General.
The first step in servicing
taken to prevent their damage. A momentary short
defective equipment is to sectionalize the fault; that is,
circuit will ruin a transistor. Insulate all but the extreme
to trace the fault to a major component or assembly.
tip of a test probe when measuring voltages. Refer to
The second step is to localize the fault to a defective
figures 6-8 and 6-9 to determine the value of a resistor
system or assembly. The third step, isolation, traces the
or a capacitor by its color coding.
fault to the defective part. Some faults, such as a
defective film transport mechanism, or the binding of
(8) Maintenance assignment charts. The
mechanical OUBLESHOOTING components, can often
maintenance allocation chart (MAC) in conjunction with
be isolated by sight, touch, or hearing. The majority of
the maintenance support plan designates.
faults, however, must be isolated by detailed electrical,
mechanical, or optical checks.
3-1
