TM 11-6625-820-45
CHAPTER 2
TROUBLESHOOTING
Section I. GENERAL TROUBLESHOOTING TECHNIQUES
t o locate the unit or units at fault by the
Warning: Be careful when working on the
following methods:
115-volt, 400-cps circuit. Serious injury or
death may result from contact with this cir-
(1) V i s u a l inspection. The purpose of
cuit.
visual inspection is to locate faults
without testing or measuring circuits.
21. General
Indications on the RMI meters, or
The general support and depot maintenance
other visual signs should be observed
procedures in this manual supplement the pro-
during all operating modes, and an
cedures in the organizational maintenance man-
attempt should be made to section-
ual. The systematic troubleshooting procedure,
alize the fault to a particular unit.
which begins with the operational and sec-
(2) Operational tests. Operational tests
tionalization checks that can be performed at
frequently indicate the general loca-
an organizational category, is carried to a high-
tion of trouble. In many instances,
er category in this manual. Sectionalizing, lo-
the tests will help in determining the
calizing, and isolating techniques used in the
exact nature of the fault. The inter-
troubleshooting procedures are more advanced.
maintenance
mediate
preventive
checks and services chart (TM 11-
2-2. Organization of Troubleshooting
6625-820-12) contains a list of op-
erational checks which helps to sec-
Procedures
tionalize troubles to a unit.
a . General. The first step in servicing a
malfunctioning test set is to sectionalize the
c. Localization. After the trouble has been
fault. Sectionalization means tracing the fault
sectionalized (b above), the methods listed be-
to a unit or circuit. The second step is to lo-
low will aid in localizing the trouble to a cir-
calize the fault. Localization means tracing the
cuit in the suspected unit. See the trouble-
fault to a defective part responsible for the ab-
shooting chart for help in finding the trouble.
normal condition. Some faults, such as burned-
RMI and meter indications or lack of indica-
out resistors and arcing and shorted transform-
tions and operational checks provides a sys-
ers can often be located by sight, smell, and
tematic method of localizing trouble to a circuit.
hearing. The majority of faults, however, must
The procedures provided in the troubleshoot-
be isolated by checking voltages and resistance.
ing charts (para 25 through 29) will provide
additional information for localizing trouble.
b. Sectionalization. Listed below is a group
d. Isolation. After the trouble has been lo-
of tests arranged to reduce unnecessary work
calized (c above), the methods in (1) through
and to aid in tracing trouble in a malfunction-
(4) below will help in isolating the trouble to a
ing test set. Test Sets, Radio AN/ARM-92
defective circuit element.
and AN/ARM-92A consist of five units; the
(1) Resistance measurements. R e s i s t -
test set, the control unit, the RMI the OBS
ance measurements are used to
indicator and the aid box. The first step is
C h a n g e 2 2-1
