Telos Zephyr, Руководство пользователя

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Section 10 ADVANCED PROBLEM SOLVING 179
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Step 2. Observe collateral behavior to gain as much information as possible about
the problem. Does the LCD's problem correlate to an LED flashing? Try to avoid
studying a problem in isolation, but at the same time be wary of trying to fix too
many at the same time. No one is smart enough to deal with multiple problems all
at once – unless they are all manifestations of something more fundamental. Always
note any messages the Zephyr may present when the problem occurs. Enlist the
help of the users to keep track of these messages and give you this information.
Keep detailed notes.
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Step 3. Round up the usual suspects. At the system level, always suspect the menu
set- up, the cables, the phone company line setup, the punch- blocks, etc. At the
component level, lots of computer problems stem from the same few sources.
Never, never, never forget to check Vcc.
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Step 4. Generate a hypothesis. Before changing things, formulate a hypothesis
about the cause of the problem. You probably don't have the information to do this
without gathering more data.
Sometimes you'll have no clue what the problem might be. Sometimes, when the
pangs of desperation set in, it's worthwhile to try anything practically at random.
You might find a bad plug, an unconnected line, or something unexpected. Look
around, but be always on the prowl for a working hypothesis.
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Step 5. Generate an experiment to test the hypothesis. Change the ISDN connection
to a known good line; call a known good Zephyr at the other end; if long- distance
doesn’t work, try a local call.
NOTE: You should plan your tests to eliminate 50% of the possible problems in one
test, if possible. Just keep careful track so you know what you have eliminated.
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Step 6. Fix the problem.
Other Ideas
Constantly apply sanity checks. Twenty years ago the Firesign Theater put out an album
called "Everything You Know is Wrong". Use that as your guiding philosophy in
troubleshooting a Zephyr set- up. For example, just because you checked the Telco line
last night and it was fine does not mean that it's OK now.
At 3:00 AM when the problems seem intractable and you're ready to give up
engineering, remember that the system has worked and will work. Never panic – you are
smarter than it is.
Diagnostic Aids
Fortunately, your Zephyr has some features which are designed to aid your
troubleshooting effort.
SEND SYNC status LED
In ISDN units, the SYNC LED is illuminated whenever power is applied. It also indicates
that the Zephyr has basic functionality. If not the Zephyr has not completed it’s boot