Chapter 3. DIRECT SUPPORT MAINTENANCE

TM 11-6720-242-35

CHAPTER 3

DIRECT SUPPORT MAINTENANCE

Section I. TROUBLESHOOTING

WARNING

(2) Sectionalization check. After a trouble has

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