TM 11-5805-239-35
CHAPTER 3
DIRECT SUPPORT MAINTENANCE
TROUBLESHOOTING TECHNIQUES
Section 1.
p u r p o s e o f visual inspection is to locate faults
3-1. General Instructions
w i t h o u t testing or measuring circuits. All vis-
procedures,
The
systematic
troubleshooting
ual signs should be observed and an attempt
w h i c h begin with the operational troubleshoot-
made to sectionalize the fault to a particular
ing checks that are performed at an organi-
unit.
z a t i o n a l level, are carried to a higher level in
c.
Localization.
Localization
consists
of
this
chapter,
These
procedures
are
more
ad
those procedures performed by direct support
vanced and require more test equipment and
maintenance
personnel
to
determine
the
gen-
material. If visual inspection of the defective
eral
area
of
trouble.
If
a
plug-in
unit
is
plug-in
power
supply
and
the
main
chassis
faulty,
replace
the
entire
unit.
Use
the
fails to determine the cause of trouble, local-
troubleshooting
chart
and
the
ization and isolation procedures are required.
operational test (para 3-8) to localize a fault.
3-2. Organization of Troubleshooting
d. Isolation. Isolation procedures are used
Procedures
by
direct
support
maintenance
personnel
to
find a faulty part of the plug-in unit (para
a. General. The first step in servicing a
defective power supply is to sectionalize the
ed, replace the part.
fault. Sectionalization means tracing the fault
to a major component. The second step is to
3-3. Test Equipment Required
localize the fault. Localization means tracing
the fault to a defective part responsible for
The chart below lists the test equipment re-
the abnormal condition. Some faults, such as
quired
for
troubleshooting
Power
Supplies
b u r n e d - o u t resistors arcing, aand shorted trans-
PP-1209(*)/FG Also listed are the associated
formers can often be located by sight, smell,
technical
manuals.
and
hearing.
The
majority
of
faults,
however,
Warning:
I n power supplies that do not
must be isolated
by
checking
voltages
and
re-
have
MWO
11-5805-239-35/1
applied,
capaci-
sistances.
tor Cl will be fully charged to the dc output
b.
Sectionalization.
Paragraph 3-5 lists a
voltage. Use a test lead with an alligator clip
g r o u p of tests arranged to reduce unnecessary
t o discharge C1 as follows: Attach the alli-
gator clip to the short probe, and clamp the
work, and the aid in tracing trouble in a defec-
tive
Power
Supply
PP-1209(*)/FG.
The
alligator clip to terminal 4 of plug P1. Place
one hand in your pocket and touch the long
first step is to locate the unit or units at
probe to terminal 3 of P1.
fault
by
means
of
a
visual
inspection,
The
3-1
