GENERAL SUPPORT TROUBLESHOOTING
Section I. GENERAL TROUBLESHOOTING TECHNIQUES
Voltages as high as 200 volts exist at various points in the digital volt-
meter. Use caution when servicing the unit with the power on. How-
ever, with the power off, the line cord disconnected, and no voltage
applied to the input terminals, the maximum voltage retained on the
filter capacitors is only 50 volts. Under these conditions, the instrument
is quite safe to work on.
field would be: if your car is overheating, the
6-1. General Instructions
problem is most likely in your cooling system.
Troubleshooting includes all techniques which
may be used to isolate a defective part or as-
c. Isolation of the Defective Component or
sembly which is causing a malfunction of some
Assembly. Determine which part or assembly
type in the equipment. This section will deal
in the suspected circuit is at fault. Any one of
with general procedures and techniques which
the troubleshooting techniques listed below may
may be used in troubleshooting the AN/GSM
identify the defective component or assembly;
64A Digital Voltmeter. Section II will provide
however, it is seldom possible to know which
troubleshooting data relating to the instrument.
technique will work on some specific problem.
It maybe necessary to try all of them.
of the Troubleshooting
6-3. Troubleshooting Techniques
The troubleshooting techniques listed here are
The troubleshooting process can be broken down
in the order in which they are usually employed
into a three-step sequence. The steps in the se-
by experienced personnel to locate a defective
quence are as follows:
component or assembly.
a. Definition of Problem. Determine in com-
a. Visual Inspection. The purpose of visual in-
plete detail what the symptoms of the problem
spection is to locate faults without further test-
are and under what conditions they may be re-
ing or measuring of the circuits. If a good instru-
produced or demonstrated. This involves con-
ment of the same type is available, compare the
ducting performance tests on the equipment and
faulty AN/GSM64A to an AN/GSM-64A in good
noting deviations from expected performance.
working order. The symptoms noted in the per-
Since some problems are intermittent it may
formance tests should provide clues about where
be necessary to repeat the tests until the mal-
to look and what to look for. Good lighting is,
function appears or to conduct the tests during
of course, essential and sometimes a magnifying
some adverse environmental stresses such as
glass is helpful. Look for the following defects.
shock, vibration, or temperature changes.
(1) Broken wires or wires with faulty in-
b. Localization of Problem. Determine the cir-
cuits that are likely to contain the fault. From
(2) Overheated resistors.
an analysis of the symptoms of the problem
noted above, it can be deduced that the defect
(3) Integrated circuit not oriented in socket
lies in some specific circuit location or locations.
properly. The index mark on the end of the
intergrated circuit must be toward the index
An example of this process in the automotive