TM
11-6130-243-14-3
CHAPTER 5
GENERAL SUPPORT MAINTENANCE INSTRUCTIONS
Section I. TROUBLESHOOTING
nature of the fault. The operator's preventive
WARNING
maintenance checks and services chart (para 34)
HIGH VOLTAGES AND CURRENTS ex-
contains a good operational test.
ist in this equipment. Serious injury or
(3) Troubleshooting chart. The troubleshooting
DEATH may result from contact with the
chart (para 5-4d) lists symptoms of common troubles
output terminals or internal circuitry.
and gives (or references) the corrective measures.
Reenergize the equipment before connec-
Such a chart obviously cannot include all trouble
ting the load and before performing any
symptoms that may occur. The repair technician
maintenance.
should use this chart as a guide in analyzing symp-
toms that may be listed.
5-1. G e n e r a l
Troubleshooting at the general support maintenance
5-3. Test Equipment Required
category includes all the techniques outlined for
The test equipment required for troubleshooting the
operator's and organizational maintenance and any
battery charger is Multimeter AN/USM223/U.
special or additional techniques required to isolate a
Multimeter AN/USM223/U is used by continuity
defective part. P a r a g r a p h 54d provides the
test and dc voltage measurements.
troubleshooting chart to be used by repair personnel.
5-4. Localizing Troubles
of Troubleshooting Pro-
5-2. O r g a n i z a t i o n
a. General. In the troubleshooting chart (d below),
cedure
procedures are outlined for localizing troubles and for
isolating troubles within the various circuits of the
a. General. The first step in servicing a defective
power supply. Refer to figure 51 for parts locations.
power supply is to localize the fault, which means
Refer to the schematic diagram (fig. FO1) to iden-
tracing the fault to a defective circuit responsible for
tify the circuit components. When trouble has been
the abnormal indication. The second step is to isolate
localized to a particular circuit, use voltage and
the fault, which means locating the defective part or
resistance measurements to isolate the trouble to a
parts. Some defective parts, such as shorted
particular part.
transformers, can often be located by sight, smell,
and hearing. Most defective parts however, must be
b. Use of Chart. When an abnormal symptom has
isolated by checking voltages and resistance.
been observed in the equipment, look for a description
of this symptom in the Symptom column and perform
b. Localization and Isolation. The first step in trac-
the corrective measure shown in the Corrective
ing trouble is to locate the circuit or part at fault by
Measures column. If no operational symptoms are
the following methods:
known, begin with item 5 of the operator's preventive
(1) Visual inspection. The purpose of visual in-
maintenance checks and services chart (para 34)
spection is to locate faults without testing or measur-
and proceed until a trouble symptom appears.
ing the circuits. All meter indications or other visual
c. Test Conditions. All checks outlined in the
signs should be observed and an attempt made to
troubleshooting chart are so be conducted with the
localize the fault to a particular part.
Power Supply connected to a power source and the
(2) Operational test. Operational test frequently
power supply output connected to Dummy Load,
indicates the general location of trouble. In many in-
Electrical DA638/U.
stances, the test will help in determining the exact
5-1
