Section Il. TROUBLESHOOTING
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.
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-
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
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
Test Panel, Indicator ID-48A/ARN
Multimeter TS-352B / U
b. Tools. Refer to the Maintenance Allocation
Chart in the appendix.
4-6. Special Materials Required
Mfr. and type
Epoxy Cement . . . . . . . . . . . . . . . . . . . . .. Eccobond
To cement window in bezel.
Emerson & Coming Inc. Canton,
Solvent, Epoxy . . . . . . . . . . . . . . . . . . . . . . Mona strip EP stripper, Mona In-
To remove or clean epoxy cement
dustries, Inc. Patterson 17, N. J.
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
the trouble. Troubleshooting instructions are based
on performance of the equipment. Depending upon