equipment has a fuse, find out why the fuse did not blow.
manual when you are preparing to adjust power
See if the correct size fuse is installed. Also make sure
s u p p l i e s . Before starting work on any electronic
there is not a short across the fuse holder.
equipment, always make sure the equipment is properly
grounded. Also make sure the rubber matting you are
3. LOOSE, BROKEN, OR
CORRODED CON -
standing on is in good condition.
NECTIONS Any connection
that is not in good
condition is a trouble spot. If it is
not causing you trouble
Although the power supplies for the consoles are
at the present, it will probably
cause problems in the
more sophisticated than the one described in this section,
future.
the troubleshooting principles are the same. Many of the
power supplies on gas turbine ships have LEDs to show
4. DAMAGED RESISTORS OR CAPACI-
when the output of the power supply is out of limits.
TORS-- A resistor that is discolored or charred has been
Usually, one LED indicates high output voltage and
subjected to an overload. An electrolytic capacitor will
another LED indicates low output voltage. There may
show white deposits at the seal around the terminals.
be still another LED that indicates a fault has occurred
Whenever you notice a damaged resistor or capacitor,
in the power supply. Remember, you must refer to the
check for a short. Make a note to replace the damaged
appropriate technical manual to understand what causes
or faulty part after you have performed your signal
each LED to light.
tracing procedures. There is no sense in risking a new
part until the trouble is located.
TESTING
After you install a power supply, apply power to the
In testing electronic power supplies, there are two
console or the electronic enclosure and look for the
following defects:
widely used methods you will use: (1) visual check and
(2) signal tracing. Because you will use both of these
1. SMOKING PARTS-- If any part smokes, or if
methods to test and maintain your ship's power supplies,
you hear any boiling or sputtering sounds, power the unit
we will describe the procedures for each of these
down immediately. Somewhere there is a short circuit
methods, starting with the visual check.
you have missed in your first inspection. Use an
ohmmeter to check the power supply once again. It is a
Visual Check
good idea to begin in the area of the smoking part.
The importance of the visual check should not be
2. SPARKING-- Tap or shake the power supply. If
underestimated because many GSEs can find defects
you hear or see any sparking, you have located a loose
right away simply by looking for them. A visual check
connection or short. Once again, check the power supply
does not take long. In fact, you should begin to see the
and repair it.
problem in about 2 or 3 minutes, if it is the kind of
If you locate and repair any of these defects, make
problem that can be seen.
a note of what you find and what you plan to do to correct
When visually checking
power supplies, you should
it. It is likely you have found the trouble. However, a
use the procedures described
in the next paragraph. You
good GSE takes nothing for granted. You must prove to
will find yourself using this
method often, as it is good
yourself that the equipment is operating properly and
not only for power supplies
but also for any other type
that no other troubles exist.
of electronic equipment.
If you do not find any of the defects we have just
Before you install any power supply in a console or
discussed, go ahead with the second check used in
electronic enclosure, look for the following problems:
testing: signal tracing. The problem is something you
cannot see directly with your eyes. You must view it
1. SHORTSExamine any terminal or connection
through the eye of your test equipment.
that is close to the chassis or to any other terminal for
the chance of a short. A short in any part of the power
Signal Tracing
supply can cause major damage. Look for and remove
any stray drops of solder, bits of wire, nuts, or screws.
Tracing the ac signal through the power supply is
It sometimes helps to shake the power supply module
the most rapid method you can use to locate trouble you
and listen for any tell-tale rattles.
cannot find by a visual check. It is helpful to use an
oscilloscope when you are testing power supplies. The
OR LEAKING
2. A DISCOLORED
idea is to trace the ac voltage from the transformer, to
TRANSFORMER--This is a sure sign there is a short
see it change to pulsating dc at the rectifier section, and
s o m e w h e r e in the power supply circuits. If the
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