STAR*TECH Journal
Ju Ly 19 87 ( 6)
The "OCTOPUS" Analyzer
(Part 2)
By William F.aton
Nickels and Dimes, Inc.
Laguna Hills, califomia
In part 1, the "Octopus" analyzer was
assenbled and discussed. Part 2 continues
with the actual testing of components.
Since each basic component being tested
projects a different display, the
component analyzer operation is the utnost
in si.nplicity. Figure 2 illustrates the
rrost comrron displays on the oscilloscope.
Because the component analyzer is an a-c
device, we are able to observe reactive
components, Lissajous and front-to-back
ratios of junction components. It is,
therefore, unnecessary to reverse the
leads.
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To become proficient in testing components
in circuit, it is only necessary for you
to recognize the conbination patterns
arising from the grouped components. If
the diode and capacitor shown in figure 4
were under test, the display shown in that
figure \\Ould be the result. The
oscilloscope presents both a Lissajous (Xe
reactance) and a 90 degree junction step,
informing us that the components are
neither shorted nor open.
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If the transistor in figure 5 contained an
electrical short between the base and
collector, the display shown would result
during testing from the base to the
collector.
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When testing transistors, check first from
the base to collector and then from the
base to emitter. A collector-to-emitter
test would have to pass through two
junctions in series and, therefore,
usually does not produce a usable result.
An ideal single junction check will
produce a 90 degree step display,
indicating a very high front-to-back
ratio. This means an open in the reverse
direction and a short in the forward
direction. A display that is open rrore
than 90 degrees is somewhat less than
perfect. The wider the angle, the less the
merit of the junction. Refer to figure 3.
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