Application Note

There’s probably not a service
engineer on the planet that
wouldn’t agree that intermit-
tent electrical faults are the
most difficult and frustrating to
trace and solve. Although these
may seem like random disas-
ters sent to test our patience,
invariably they have a sound
physical cause. The trick, of
course, is to discover what this
could be without spending
hours monitoring the offending
equipment until the elusive fault
finally chooses to show itself.
In this article, Henk ter Harm-
sel, Senior Product Specialist at
Fluke Industrial, The Nether-
lands, explains how the service
engineer’s life can be made
infinitely easier with the power-
ful troubleshooting features of
Fluke’s 190 Series II ScopeMeter.
Although usually highly
complex, modern electrical and
electronic equipment is also
incredibly robust, with masses
of protection circuitry to guard
against breakdown induced by,
for example, current and voltage
surges, mains harmonics, EMI…
you name it! This complexity, of
course, also has its down side
when it comes to maintenance.
Intermittent faults in particular,
always the curse of the service
engineer or technician, can
become a major headache to
trace in today’s ultra-sophis-
ticated systems with their fast
and complex control signals.
Fortunately the situation is far
from hopeless since intermit-
tent faults share one infuriating
characteristic—despite their
apparent randomness, they all
fall into several well-defined
categories. This offers an impor-
tant clue to tracing and solving
them; a fact recognized by Fluke
when designing its 190 Series II
ScopeMeter.
Troubleshooting with
the Fluke 190 Series II
ScopeMeter
Any number of factors can lead
to spurious signals that may
cause equipment to suddenly
drop out for no apparent reason.
Some of these are equipment
related, for example, defective
circuitry, dry solder joints, dust
or corrosion, and overheating.
Others, such as mains fluctua-
tions and voltage spikes due to
systems switching on, are
related to the mains supply.
Identifying the most likely cause
requires experience and intu-
ition and, in many instances, a
lot of luck.
Now, however, with the Fluke
190 Series II ScopeMeter, luck
doesn’t have to enter the equa-
tion. This family of handheld
test tools combines the func-
tions of digital multimeter with
a digital storage oscilloscope
in bandwidths up to 200 MHz
and with up to 2.5 GS/s real-
time sampling per channel. The
series also offers highly innova-
tive trouble-shooting features
found in the past only on very
expensive desktop oscilloscopes.
Available for the first time in a
portable instrument, these fea-
tures make the job of a service
engineer much easier, enabling
him or her to trace and solve all
manners of intermittent faults.
Tracking down faulty
wiring
The scope continuously records
the last 100 screens in First-in/
First-out (FIFO) memory. As soon
as you spot an anomaly on the
scope or suspect something has
occurred that you might have
missed, the Replay button can
be pressed to freeze the last 100
screens and allow you to play
them over again. The feature,
in fact, allows two sets of 100
screens with individual time
stamps to be stored for later
recall or downloaded to a PC for
a more detailed analysis.
The last 100 screens are
available for scroll-through pic-
ture by picture, or replayed as a
“live” animation.
Troubleshooting made
simple with the Fluke
190 Series II ScopeMeter
®
The last 100 screens are available for scroll-through picture by
picture, or replayed as a “live” animation.
Application Note
From the Fluke Digital Library @ www.fluke.com/library