DIRECT SUPPORT AND GENERAL SUPPORT
5-1. General Instructions
common troubles and gives corrective measures
(or references). Such a chart cannot include
Troubleshooting at the direct support and gen-
all trouble symptoms that may occur; therefore,
eral support maintenance categories includes all
the repairman should use this chart as a guide
the techniques outlined for organizational main-
in analyzing symptoms that may be listed.
tenance and any special or additional techniques
(4) Resistor and capacitor color code dia-
grams. Color code diagrams for resistors and
5-4d provides the troubleshooting chart to be
used by the repairman.
ance, voltage rating, and tolerance information.
5-3. Test Equipment Required
a. General. The first step in servicing a de-
The test equipment required for troubleshooting
fective power supply is to localize the fault,
which means tracing the fault to defective cir-
cuit responsible for the abnormal indication.
The second step is to isolate the fault, which
means locating the defective part or parts. Some
defective parts, such as burned resistors and
a. General. The troubleshooting chart (d)
outlines procedures for localizing troubles and
sight, smell, and hearing. Most defective parts,
for isolating troubles within the various circuits
however, must be isolated by checking voltages
parts location. Refer to the schematic diagram
b. Localization and Isolation. The first step in
pending on the nature of the operational symp-
tracing trouble is to locate the circuit or part
toms, one or more of the localizing procedures
at fault by the following methods:
will be necessary. When trouble has been lo-
(1) Visual inspection. The purpose of visual
calized to a particular circuit. Use voltage and
inspection is to locate faults without testing or
measuring circuits. All meter indications or
to a particular part.
other visual signs should be observed and an
b. Use of Chart. When an abnormal symptom
attempt made to localize the fault to a particular
is observed in the equipment, look for a descrip-
tion of the symptom in the Symptom column
(2) Operational test. Operational test fre-
and perform the corrective measure given in
quently indicate the general location of trouble.
the Corrective meaaures column.
In many instances, the test will help in deter-
mining the exact nature of the fault. The oper-
c. Conditions to Test. All checks outlined in
the troubleshooting chart are to be conducted
a good operational test.
with the power supply connected to a 220- or
440-volt power source. The output cables should
(3) Troubleshooting chart. The trouble-
be connected to a load.
shooting chart (para 5-4d) lists symptoms of