Try to determine the order in which
symptoms developed.
3 Determine probable causes.Perform a
thorough visual inspection, and repair
obvious problems before diving into
lengthy testing procedures. Have the
appropriate service manual or wiring
diagrams available if at all possible
(unfortunately, this is often not possible).
Think about subsystems and ancillary
components that could contribute to or
cause the problem.
4 Narrow the list of causes.Use the history
and symptom conditions to narrow down
the list of probable causes. If more thanone symptom exists, are there common
causes? Avoid preconceived ideas. Follow
test procedures step by step, skipping
none.
5 Test all subsystems.Test the most likely
cause first. Follow any manufacturer-
recommended procedures.
Following these logical steps to trou-
bleshooting may seem like the medical history
a doctor gathers when trying to figure out
what ails you, and for good reason: the
method works. Used in combination with the
best, most capable equipment, this method
will definitely increase your odds for success.
Now let’s get started!12 marine troubleshooting
Use an oscilloscope to
check AC power quality
and harmonics
(Chapter 7).If the symptom is only present
when the device is powered by
one AC power source versus
another, the problem is almost
always related to AC waveform
or harmonic distortion. Use an
oscilloscope to pinpoint.Use process of elimination, which is often time consuming and frustrating.NEW METHOD
OLD METHOD
Audio and video
systems affected by “bad”
power: random diagonal lines
showing on screens and
background noise is heard
over speakers/radio.SYMPTOM
Electronics (3)NEW METHOD
OLD METHOD
SYMPTOM
Use a multimeter set to ohms to track through circuits from one termination point to another. Some termination
points may be inaccessible.Use a TDR to check the integrity of the
network cable (Chapter 3).Use process of elimination if necessary and
be sure to check all individual conductors in
the cable.
One electronic device
is not “talking” to another
(e.g., a chartplotter or autopilot
is not receiving data
from a GPS).Electronics (2)