Re: Help T-shooting boot problem

Melodious Thunk <thunk.melodious@xxxxxxxxx> wrote:

System is a dual G4 450 MHz, OSX 10.4.11. I think the system is called
the "gigabyte ethernet."

For future reference: GigaBIT Ethernet. :-)

The symptom is, normal chime on power-up, normal load screens, but
login screen never appears. Instead, I get a blue screen with a <
1sec. flash of cursor every ten seconds or so; the system is failing
at the point the cursor *should* reappear on the screen and the login
screen should appear. At that point, it keeps re-trying (the flash of
cursor reappears every ten seconds) indefinitely.

By "cursor" do you mean the mouse pointer?

So far, not enough information to identify what is going on, but I can
think of some things you could try to reduce the scope of the problem.

Machine would not boot with all external connections, except monitor,
removed. I think that isolates it down to the cpu. Monitor (&
presumably video card) appear normal, I see all this on its normal
monitor. Only unusual symptom before this failure was, about two days
ago, a Darwin "dump" appeared onscreen.

Kernel panic? Screen greyed out with a multi-language message saying you
must restart the computer, or the text-based variant of it which shows
register contents.

Made me think there might be some memory problem... except for that
"normal" chime, that is. Doesn't the chime indicate hardware test passed?

Yes. The startup chime means that the basic power on self-test has
passed, including RAM.

Unfortunately it isn't a very comprehensive RAM test and some types of
fault can pass undetected. You get a more reliable RAM test using the
Apple Hardware Test CD that was supplied with the computer, or an even
better one (which can take hours to run) using the memtest utility in
Single User mode (difficult to set up if your computer isn't able to
boot).

A kernel panic doesn't necessarily mean a hardware fault. It could be
corrupted system software or a bug in kernel-level software (either
Apple or third party).

Have tried pulling the battery & pressing the internal reset switch.
(I thought there were two switches internal, but only found one; maybe
it was later systems that had two.)

There is usually only one - Power Management Unit reset.

Some models have no internal reset button and do the PMU reset with a
special key and/or button combination.

When I inserted a Tiger install disc (retail version) & pressed "C" on the
keyboard, I got the same symptoms, as if it never tried to boot from the
DVD (combo drive).

Two possibilities occur to me: either your USB (or keyboard) is not
working, or your computer thinks it has an Open Firmware password.

Try holding down the Option key while starting up. Does it go into the
startup disk selector, or ask you for a password?

If it tries to boot from the hard drive (Apple logo and spinning
pinwheel), then I suspect your USB interface is dead or there is a
problem with the keyboard.

Any ideas? It there a tech note that describes the sequence of events
*after* OSX has loaded & *before* the login screen appears?

If your keyboard is working you can start up in Verbose mode by holding
down Command-V at startup. This displays progress information in text
form. Some of it is difficult to interpret but it might give some clues.
--
David Empson
dempson@xxxxxxxxxxxxx
.