Page 25 - Troubleshooting Analog Circuits

12 I. First Things First

Medicine. He recently told the Los Angeles Times, “With the advent of all the new
technology, physicians aren’t all that much interested (in bedside medicine) because
they can order a $300 to $400 test to tell them something they could have found by
listening.” An editorial accompanying the study commented sadly: “The present
trend. . . may soon leave us with a whole new generation of young physicians who
have no confidence in their own ability to make worthwhile bedside diagnoses.”
Troubleshooting is still an art, and it is important to encourage those artists.

The Computer Is Your Helper.. . and Friend.. . ???

I read in the San Francisco Chronicle (Ref. 5) about a case when SAS, the
Scandinavian airline, implemented an “Expert System” for its mechanics:
“Management knew something was wrong when the quality of the work started
decreasing. It found the system was so highly mechanized that mechanics never
questioned its judgment. So the mechanics got involved in its redesign. They made
more decisions on the shop floor and used the computer to augment those decisions,
increasing productivity and cutting down on errors. ‘A computer can never take over
everything,’ said one mechanic.‘Now there are greater demands on my judgment,
(my job) is more interesting.”’ What can I add? Just be thoughtful. Be careful about
letting the computers take over.

No Problems?? No Problem.. .Just Wait.. .

Now, let’s skip ahead and presume we have all the necessary tools and the right re-
ceptive attitude. What else do we need? What is the last missing ingredient? That
reminds me of the little girl in Sunday School who was asked what you have to do to
obtain forgiveness of sin. She shyly replied, “First you have to sin.” So, to do trou-
bleshooting, first you have to have some trouble. But, that’s usually not a problem;
just wait a few hours, and you’ll have plenty. Murphy’s Law implies that if you are
not prepared for trouble, you will get a lot of it. Conversely, if you have done all your
homework, you may avoid most of the possible trouble.
I’ve tried to give you some insights on the philosophy of how to troubleshoot.
Don’t believe that you can get help on a given problem from only one specific
person. In any particular case, you can’t predict who might provide the solution.
Conversely, when your buddy is in trouble and needs help, give it a try-you could
turn out to be a hero. And, even if you don’t guess correctly, when you do find out
what the solution is, you’ll have added another tool to your bag of tricks.
When you have problems, try to think about the right plan to attack and nail down
the problem. When you have intermittent problems-those are the nastiest types-
we even have some advice for that case. (It’s cleverly hidden in Chapter 12.) So, if
you do your “philosophy homework,” it may make life easier and better for you.
You’ll be able not only to solve problems, but maybe even to avoid problems. That
sounds like a good idea to me!

References

1. Dostal, Jiri, Operational Amplifiers, Elsevier Scientific, The Netherlands, 198 1; also, Elsevier
Scientific, Inc., 655 Avenue of the Americas, NY, NY 10010. (212) 989-5800 ($1 13 in 1990).
2. Smith, John I., Modern Operational Circuit Design, John Wiley & Sons, New York, NY, 1971.