Section Il. TROUBLESHOOTING - TM-11-5840-270-24-10012

TM 11-5840-270-24-1

Section Il. TROUBLESHOOTING

4-3. Scope

measuring circuits. All visual signs should be

observed and an attempt made to sectionalize the

The systematic troubleshooting procedure, which

fault to a particular section of the indicator.

begins with the operational and sectionalization

(2) Operational tests. Operational tests

checks that can be performed at organizational

frequently indicate the general location of trouble.

level, is carried to a higher maintenance category in

In many instances, the tests will help in deter-

this section. Sectionalizing and isolating techniques

mining the exact nature of the fault. Operational

used in the troubleshooting procedures are more

tests are given in section VI of this chapter.

advanced.

c. Localization. After the trouble has been

4-4. Troubleshooting Procedures

sectionalized (b above), the methods in (1) and (2)

a. General. The first step in servicing a defective

below will aid in localizing the trouble to a defective

i n d i c a t o r is to sectionalize t h e fault. Sec-

circuit element.

tionalization means tracing the fault to a major

(1) Resistance measurements. Make resistance

component. The second step is to localize the fault.

measurements on the indicator only as directed in

Localization means tracing the fault to a defective

paragraphs 4-20 and 4-26.

part responsible for the abnormal conditions. Some

(2) Intermittent troubles. In all the tests, the

faults, such as burned out resistors, cracked in-

possibility of intermittent troubles should not be

sulation, or damaged mechanical parts can often be

overlooked. If present, this type of trouble often

may be made to appear by tapping or jarring the

located by sight, smell, or hearing. The majority of

indicator. Make a visual inspection of the wiring

faults, however, will be located by injecting

and connections of the indicator.

simulated operating signals and observing the

results on the indicator displays.

4-5. Tools and Test Equipment Required

b. Sectionalization. Listed below are tests

The following is a listing of tools, test equipment,

arranged to reduce unnecessary work and to aid in

and the associated technical manuals required for

tracing trouble in a defective indicator.

troubleshooting the indicator.

(1) Visual inspection. The purpose of visual

a. Test Equipment.

inspection is to locate faults without testing or

Technical manual

Test equipment

Common name

Test Panel, Indicator ID-48A/ARN

None.

Test Panel

TM 11-6625-366-15

Multimeter TS-352B / U

Multimeter

b. Tools. Refer to the Maintenance Allocation

Chart in the appendix.

4-6. Special Materials Required

Item

Mfr. and type

Use

Epoxy Cement . . . . . . . . . . . . . . . . . . . . .. Eccobond

To cement window in bezel.

Emerson & Coming Inc. Canton,

Mass.

Solvent, Epoxy . . . . . . . . . . . . . . . . . . . . . . Mona strip EP stripper, Mona In-

To remove or clean epoxy cement

dustries, Inc. Patterson 17, N. J.

residue.

the nature of the operation trouble symptom, one or

4-7. Troubleshooting Chart

more localizing procedures will be necessary. The

a. General. The troubleshooting chart in this

troubleshooting chart lists abnormal indications

section supplements the operational tests contained

and probable causes for the tests performed in

i n s e c t i o n s V and VI. The chart indicates

section VI. Perform the tests and refer to the

operational symptoms, probable troubles, and

troubleshooting chart if correct readings cannot be

corrective measures that should be taken to remedy

obtained.

the trouble. Troubleshooting instructions are based

on performance of the equipment. Depending upon

4-2