the circuit diagrams before you begin troubleshooting;
this simplifies the task of isolating the trouble. When a
circuit fails to function, you should use the logic
diagram approach to locate the fault. The
trial-and-error method of locating the fault(s) in a circuit
is inefficient and time-consuming. If you have not been
trained in electricity, you should read the Navy
Electricity and Electronics Training Series (NEETS)
Modules, particularly modules 2, 3, and 4. If you
already possess knowledge about reading diagrams, the
NEETS Modules can help you "get up to speed." Once
you understand electrical diagrams, know prescribed
maintenance and trouble-shooting procedures, and can
use a voltmeter, you should be able to analyze and locate
most of the faulty electrical components in imaging
When working with electricity, Sailors commonly
refer to all electrical diagrams as "schematics." This,
however, is not correct. A schematic is a specific type
of diagram with characteristics of its own and with a
specific purpose. Each of the different diagrams has a
specific purpose and has distinguishable features that
set it apart from the others. These diagrams may be used
to do the following:
learn the operation of a specific system
locate the components of a system
identify the components of a system
trace a circuit
The simplest of all diagrams is the pictorial
diagram. The pictorial diagram is a picture or sketch of
the components of a specific system and the wiring
between these components. This simplified diagram
identifies components, even if you are not familiar with
their appearance. This type of diagram does not show
physical locations of components or the manner in
which the wiring is marked or routed. It does, however,
show you the sequence in which the components are
connected (fig. AII-1). After studying the pictorial
diagram, you should recognize the components and
how they are connected to one another.
Figure AII-1Pictorial diagram of a pump assembly.
The purpose of an isometric diagram is to help you
locate a component within a system. This type of
diagram shows you the outline of a processor, printer,
or other piece of equipment. Within the outline, the
various components of a system are drawn in their
respective (or relative) locations. The isometric
diagram also shows interconnecting cables running
between components (fig. AII-2).
A block diagram (fig. AII-3) presents a general
description of a system and its functions. This type of
diagram is often used with accompanying text material.
A block diagram shows the major components of a
system and the interconnections of these components.
All components are shown in block form and each block
is labeled for identification purposes.
The single-line diagram (fig. AII-4) is used
basically for the same purpose as the block diagram.
When the single-line diagram is used with text material,
it provides you with a basic understanding of the
components and their functions in a system.
There are two major differences between the
single-line diagram and the block diagram. The first
difference is that the single-line diagram uses symbols,
rather than labeled blocks, to represent components.
Second, the single-line diagram is just thatall
components are shown in a single line. There are no