The multimeter contains circuitry that allows
measurements. Work with one hand whenever
it to be a voltmeter, an ammeter, or an ohmmeter.
possible.
A multimeter is often called a volt-ohm-milliam-
meter (VOM).
The VOM does have two disadvantages--it
Multimeter
can load the circuit under test, and the meter
movement is easy to damage because of improper
The process of fault detection often leads
testing procedures.
beyond visual inspection and power checks. Use
a voltmeter to find out if a power circuit is deliver-
Two common multimeter are the Simpson
260 and the newer digital model Fluke 8100A. See
ing power to the proper place. However, the
figures 9-8 and 9-9.
voltmeter won't identify what is wrong. An
ohmmeter is a better instrument for identifying
Ohmmeter
the problem. With the ohmmeter, you can find
Use an ohmmeter to measure circuit continuity
opens, shorts, grounds, or incorrect resistance
values. With schematics you can trace circuits
and total or partial circuit resistance. An ohm-
meter is shown in figure 9-10. The ohmmeter's
until you isolate the trouble.
Figure 9-8.-Standard multimeter.
9-14
