- Macintosh System Troubleshooting - Relative
Success and Failure
- Apple Engineers did an in-depth report of
troubleshooting methodologies and their effectiveness.
This sample covers cases with more than four support
calls on the same issue during an 8-week period, where
the issue was crashing and freezing.
- Extensions troubleshooting worked 56% of the times
it was tried.
- Clean Installs worked 28% of the time they were
- Disconnecting SCSI Devices worked 21% of the time
that it was tried.
- These are all valid troubleshooting steps (they
have a higher percentage of fixing a customer's
- Extensions Conflict, Corruption, or
- Extensions troubleshooting is the most widely
applicable troubleshooting step. It is appropriate for
any error type 1, 2, 3, 10, 11, 25 or freezing in
addition to miscellaneous wierd behavior. If the issue
occurs on startup or in multiple applications, this is
the best bet.
- Clean Install:
- When all third-party hardware and software have
been eliminated and the issue persists on startup or
in multiple applications. Reinstalling system software
may be appropriate. A clean install is not necessary
if a custom-install or easy install will fix it. If
you have narrowed down the issue to a certain file or
the issue seems only to affect a certain component of
the system software, you should be able to quickly
custom-install that item and fix the issue. A
custom-remove is also not, strictly speaking,
necessary before a custom-install. There is a lot of
recovery reqiured after a clean install. Many
customers do not understand how to recover from a
clean install and this can cause multiple callbacks.
It's good to avoid unless simpler steps don't fix it.
At times it is appropriate, but other times, it's
overkill. You can save a lot of time here by doing the
quickest thing to solve the customer's issue, not the
easiest. This will be easier to judge as you gain
- Disconnecting SCSI devices.
- This step is appropriate when a computer starts
with a gray screen and a pointer only and goes no
further. Random, hard freezes and recurring directory
corruption can also be signs of SCSI chain problems.
Many customers do not realize that ALL SCSI devices
must ALWAYS powered on BEFORE the computer is started
and then left on at all times while the computer is
being used. There are no exceptions to this rule. This
is explicitly stated in every CPU manual put out for
the last two years. Customers often miss this point
and have chronic problems because of it.
- In contrast, the following troubleshooting
steps were shown to be tried way TOO OFTEN:
- Rebuilding the Desktop worked 0% of the time that
it was tried. It was tried 54% of the time.
- Deleting Preferences worked 3% of the time that it
was tried. It was tried 38% of the time.
- Zapping the PRAM worked 5% of the time that it was
tried. It was tried 77% of the time.
- From this we conclude that time spent
telling/helping customers to do these things is, for
the most part, wasted. In an effort to provide
relevant troubleshooting to customers, please try to
limit the use of these steps to the following
- Rebuilding the Desktop should only be tried to
resolve generic file icons (but not the generic
chooser icon in Mac OS 8.1). A single generic icon is
often a file level problem (such as a bundle bit),
that rebuilding the desktop won't fix. In rare cases,
application/document connection problems can be fixed
by rebuilding the desktop. (For example, you
double-click on a document and it opens the wrong
application. However, this Mac OS Easy Open does this
same thing by design.). This can easily waste several
minutes on a call, especially on the large drives in
- Moving Preferences should only be tried when an
issue is isolated to a specific item (Finder, control
panel, application). Usually, the program will crash
on startup or the application-specific settings fail
to "stick" when you quit the application. It is not
necessary to actually delete the preferences, just
- Resetting the PRAM should only be tried in
cases where PRAM-resident settings are not "sticking".
These settings include startup disk, keyboard control
panel settings (repeat rate, delay until repeat),
sound level, memory control panel settings (RAM Disk,
Virtual Memory, Disk Cache, 32-bit Addressing), mouse
control panel settings (double-click speed, tracking
speed), selected AppleTalk port, highlight color,
default printer, Date & Time Control Panel (Time
Zone, Daylight Savings Time ONLY), General Controls
(Folder Protection, Insert Blink, Menu Bar blink
ONLY), plus undocumented features. Keep in mind that
resetting the PRAM resets ALL of those settings to
their defaults and causes the customer to have to
reset any that he customized. The following control
panels are not affected by zapping PRAM: Energy Saver,
File Sharing, Text, Numbers, Speech, PPP, TCP/IP and
- Resetting PRAM can affect ADB and serial port
issues and little else.
- As a reminder (and as I mentioned previously)
reformatting the hard drive should never even be
attempted unless Disk First Aid reports problems that
it cannot fix. Unless a bad hard drive is suspected, a
low-level format should also NEVER be tried. Zeroing
all data should also NEVER be tried if the customer
doesn't specifically ask how to totally prevent data
- Hopefully increased awareness of the futility
of these things will reduce the amount of time wasted
on irrelevant troubleshooting. If logical
troubleshooting fails, it is probably better to
consult with a outside technician.