Helpful Tips
What
to Do When Your Macintosh Won’t Boot and Other Horrors
What
did you do right before it broke all by itself? Sometimes you know what happened.
Did you install new
software or hardware shortly before the problem developed?
Did you throw away any “mystery” files from your system folder (OS
9)? OS X users, did you start up in
OS 9 and see weird files in the root directory and relocate or trash them?
Check the Easy Stuff First (sometimes
you get lucky)
-
Remove ALL external devices (even keyboard and mouse), and try booting
again. A USB or SCSI device gone
bad can cause the boot failure. Check
power cord and connections.
-
Do you see a happy Mac icon at startup?
This means that the computer has found a bootable hard drive — a good
sign. If the boot process fails
after you see the happy Mac icon it is likely to be a software issue (not
always).
-
Will the computer boot with extensions turned off (OS 9) or in Safe Mode
(OS X 10.2 or later)? (Hold down
the shift key on startup.) If yes,
problem is due to an Extension conflict or corruption (OS 9) or corruption of a
kernel extension (OS X). This is a
software problem. Diagnosis of this
type of problem can be very tedious, so at this point I usually perform a clean
reinstall of system software (it usually saves time in the long run).
-
Will computer boot from system CD (put system CD into drive and boot
computer holding down the “C” key)? If
it will boot and run normally, the problem is likely to be a software problem.
We have ruled out most hardware problems; it could still be a failed (or
failing) hard drive (unfortunately this is more common than any of us would
like) or a bad ribbon cable to the hard drive.
-
Do you see a flashing question mark with everything else being normal? This
means that the computer cannot find a bootable disk. This symptom can be caused by corrupted system software or a
failing hard drive. Especially if you have recently reset the PRAM or replaced
the battery, try this (it is easy and it can’t hurt anything).
Boot from a CD, go to the “Startup Disk” control panel or preference
pane and select your hard drive or boot partition, then reboot.
If
the Computer Will Boot From a CD, But Not From the Hard Drive
-
A disk-repair utility, such as Disk
First-Aid which can be found on all pre-OS-X installation CD’s, or Disk
Utilities which can be found on all OS X installation CD’s, can be very
helpful. They can sometimes repair
a damaged file structure. There are
third-party utilities which are available; Norton Utilities, Tech Tools and Disk
Warrior can all be useful, they all fix different things.
The utilities which Apple provides are quite effective.
-
Re-install system software.
-
Reformat the hard drive and
reinstall the system software (this is a last resort because reformatting the
drive destroys ALL of your data).
-
If all of this fails to fix the
problem, replace the hard drive (check ribbon and power cables to hard drive
before doing anything drastic).
If the Computer Will Not Boot From a CD
– Diagnosis of Hardware Problems
-
Is the power light on?
If not, the problem is likely to be failure of the power supply.
The computer’s components are not receiving any power.
-
Is
there a startup tone?
A single startup tone indicates that the computer has successfully
completed its internal tests. If
the startup tone is heard as several tones instead of one, test for bad RAM.
This can be caused other things, but failure of the RAM test at startup
is the only one that is easy for the user to test.
If your macintosh has DIMM’s (all G3 and G4’s), test RAM by removing
one DIMM and rebooting. If the problem is resolved you have found the problem.
If your mac has SIMM’s they must be removed in pairs.
-
Monitor
remains black, but there is a normal
startup tone, you hear the usual fan and hard disk noises. This could be caused by a bad video card (make sure that the
display is plugged into the computer and has power). In many Mac models this can be caused by a dead back-up
battery.
-
Do
you hear any noises?
Normal noises.
Do you hear the hard drive spinning and making normal clicking noises?
You may need to open the case to tell.
There are also fans inside the case which add to the internal noise.
If the hard drive is not spinning, make certain that its connections are
secure; if there is no loose connection you will need to replace the hard drive.
Unusual noises.
Screeching or loud clicking noises can be caused by a hard drive head
crash. This probably means that you
will be replacing the hard drive, and that you have lost all of your data.
Other sources of unusual noises are the fans (in the power supply, and
often on the video card); a bad fan bearing can cause a loud squealing noise.
A failing fan will not cause boot failure.
No noises.
The power light on the front of your G4 is on, but you don’t hear
anything; no fans, no hard drive noises, the monitor remains black.
This can be caused by an internal power management problem.
Reset the PMU (Power Management Unit), a small integrated circuit which
controls power distribution to all of the computer’s components. There is a similar power management reset switch in G3
computers (and some G4’s) it is called the CUDA.
Kernal Panics (OS X)
You are happily
working at your computer when, suddenly white lettering on a black background
appears right on top of what you have been working on, and your computer
freezes. This is called a kernel
panic. It happens when the
operating system receives an unknown command or a command that has been executed
incorrectly. Since the advent of
version 10.2.4 the white letters on a black background do not always appear, the
only visible symptom is that the computer freezes or you see a blue screen (the
blue screen can also be displayed at startup if a kernel panic occurs then).
The text logged by the kernel panic can sometimes be useful to the Apple
technicians if they are trying to diagnose a problem, but it is not usually very
informative to the average user. If
kernel panics occur frequently on your mac, try to recall when they started; had
you just installed some new software or hardware (a printer, a new video card)?
If you have recently installed something new, that installation is likely
the cause of the problem. Uninstall
the device. If you have not
recently installed something new, the problem is often solved by a
reinstallation of the OS X software (archive and install).
This will replace system software which has become corrupted.
Hardware Problems That Can be Fixed by
the (non-nerd) User
-
A user can replace a hard drive, a CD/DVD drive, ribbon or power cables,
RAM, backup battery, keyboard or mouse.
-
Reset CUDA or PMU (Power Management Unit)—This procedure varies
depending on the model of Macintosh; for detailed instructions go to http://www.info.apple.com/
and search on “reset PMU”. Remember
that the PMU is a static-sensitive micro chip; be sure that you have grounded
yourself before touching the reset switch.
Reset NVRAM (Non-Volatile RAM) or PRAM
(Parameter RAM) (these are the same thing)
PRAM keeps track of things like startup disk,
time zone, and network preferences. Occasionally
PRAM becomes corrupted which can cause unpredictable results and general
flakiness. To reset, restart the
computer; as soon as you hear the startup tone, hold down the Command, Option,
“p” and “r” keys. You
should hear the startup tone again. Keep
holding until you have heard the startup tone a total of three times.
Repairing
Permissions (OS X 10.2 and later) –This
repair fixes a problem which results in the user being unable to do common
things, like open certain files or print (often the first symptom noticed).
OS X is UNIX; in a UNIX system each file has a list of permissions
associated with it, occasionally these become corrupted.
To repair permissions, boot from an OS X installation CD.
Instead of running the installer run “Disk Utility” (this is a menu
item). Select the your hard drive in the list of drives, click on the “First
Aid” tab, then click the “Repair Permissions” button.
This often fixes a multitude of mysterious problems.
Bad
RAM or Not Enough RAM
If your computer performs as expected most
of the time but crashes when you
have ten applications open, the cause could be insufficient RAM available for
what you are trying to do. If this
occurs often, test your RAM and replace any found to be unreliable.
If your RAM proves to be reliable, install more RAM in your computer.
Shortcuts that sometimes work (OS 8 and
9)
-
Throw the file called “Finder Preferences” into the trash then
reboot. This file is always open
when the computer is running and occasionally becomes corrupted.
It is a likely culprit especially when the computer boots almost
completely and then freezes.
-
Start up from an installation CD, throw the files called “System” and
“Finder” into the trash (both are inside the System Folder), then run the
installer. Sometimes this trick can
save you having to do a clean reinstall of the system software.
What You Can Do to Help Prevent Problems
-
Run “Software Update” regularly.
-
Check the manufacturer’s web site for updates and bug reports BEFORE
installing anything. Make sure that
the product is compatible with the version of the system software that you are
using.
-
If you are running OS X, create an additional user with administrative
privileges.
Preference
files and other system-necessary components in the individual user library
occasionally become corrupted, causing problems like an internal optical drive
not mounting, jumping cursors, and overall sluggish operation.
If there is a second account which is not corrupted, you can log on and
make repairs (although this takes quite a bit of arcane knowledge).
Or you can transfer your files to that user.
Don’t
rename, relocate to throw away system-installed files or folders while started
up in OS 9 or in OS X while logged on as the root user.
Shortcut Keys
Macintosh OS Modifier keys
Keyboard Shortcut Commands
Modifier keys are the Shift, Command (Apple key), Option, and Control keys. A modifier key (or combinations of
modifier keys) must be pressed continuously before clicking a letter, number or symbol to complete a command.
Reminders of the shortcuts appear to the right of pull down menu selections.
Modifier keys can be understood by using Key Caps.
Key Caps - select from the Apple menu
