TM 11-5826-225-35
CHAPTER 2
TROUBLESHOOTING
Section 1. GENERAL TROUBLESHOOTING TECHNIQUES
(1) Visual inspection. The purpose of
2-1. General
visual inspection is to locate faults
The dirtect support, general support, and
without testing or measuring circuit.
depot maintenance procedures in this manual
Indications on the aircraft healing
supplement the procedures outlined in the
i n d i c a t o r and on the control unit
operator's and organizational maintenance
tuning meter or other visual signs
manual. The systematic troubleshooting proce-
should be observed during all oper-
dure, which begins with the operational and
ating modes, and an attempt should
sectionalization checks that can be performed
be made to sectionalize the fault to a
at an organizational level, is carried to a higher
particular unit.
level in this manual. Sectionalizing, localizing,
(2) 0perational tests. O p e r a t i o n a l t e s t s
and isolating techniques used in the trouble-
frequently indicate the general loca-
shooting procedures are more advanced.
tion of trouble. In many instances, the
tests will help in determining the exact
2-2. Organization of Troubleshooting
nature of the fault. The intermediate
preventive maintenance checks and
a. General. The first step in servicing a mal-
services chart (TM 11-5826-225-12)
functioning direction finder set is to sectionalize
contains a list of operational checks
the fault. Sectionalization means tracing the
which helps to sectionalize troubles to
fault to a unit or circuit. The second step is to
a unit.
localize the fault. Localization means tracing
the fault to a defective part responsible for the
c. Localization. After the trouble has been
abnormal condition. Some faults, such as
sectionalized ( b above), the methods listed in
burned-out resistors, and arcing and shorted
(1) through (3) below will aid in localizing the
transformers or motors, can often be located
trouble to a circuit, stage, or mechanical sys-
by sight, smell, and hearing. The majority of
tem in the suspected unit.
fault, however, must be isolated by checking
(1) Troubleshooting chart. Tuning meter
voltages and resistances.
and bearing indicator indications or
b, Sectionalization. Listed below is a group
lack of indications and operational
of test arranged to reduce unnecessary work,
checks provide a systematic method of
and to aid in tracing trouble in a malfunction-
localizing trouble to a circuit, stage, or
ing direction finder set, Direction Finder Set
mechanical system. The trouble symp-
AN/ARN-88 consists of five units; the control
toms listed in the troubleshooting
unit the receiver, the mounting, the inverter,
charts ( paras 2-5d and 2-9b ) will pro-
and the loop antenna. The first step is to locate
vide additional information for local-
the unit or units at fault by the following
izing trouble.
methods:
2-1
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