I've been getting a lot of grief with a dual G4 Gigabit Ethernet lately.

Its Power Management Unit seems to have gone flaky and I regularly have
to reset it, reset the PRAM, and reset nvram and other values in open
firmware just to keep it stable for a few days at a time.

It has an unpleasant tendency to shut down unprovoked, sometimes in the
middle of a startup, other times after hours of deep sleep, as it wakes
up. Occasionally, it refuses to start up without extra resetting /
unplugging of USB devices, etc. The battery has already been changed.
The Mac may (I'm really unsure, just surmising) have grown
ultra-sensitive to lousy Houston power despite a good surge protector.

The worst abuse I remember submitting the machine to has been to install
a new PCI card with the power cord still plugged in. If that is enough
to damage the PMU, Apple might extend warranties to cover that for a
reasonable fee, as no clear warning about that vulnerability is present
in the user manual.

In article <3EDBE70C.3000309[at]KaNine_University.edu>,
"Fetch, Rover, Fetch" <Fun_Fur[at]KaNine_University.edu> wrote:

> try:
> unplug everything
> open the machine
> near the battery there is a button (power reset)
> push it
> put it all back together again
>
> cardinal wrote:
> > mac-guru's
> >
> > I have a 800MHz Quicksilver running OS X 10.2 that is randomly
> > powering down. Doesn't seem to be app related as it's happened in lots
> > of different apps and many times when the screen saver is running.
> >
> > Seems to happen less when I have the case open which leads me to
> > believe that it *may* be heat related, but at this point that is just
> > a guess.
> >
> > Has anyone seen or heard of this problem before? It's driving me nuts
> > :-)
> >
> > thanks in advance
>

> >
> > cardinal wrote:
> > > mac-guru's
> > >
> > > I have a 800MHz Quicksilver running OS X 10.2 that is randomly
> > > powering down. Doesn't seem to be app related as it's happened in lots
> > > of different apps and many times when the screen saver is running.
> > >
> > > Seems to happen less when I have the case open which leads me to
> > > believe that it *may* be heat related, but at this point that is just
> > > a guess.
> > >
> > > Has anyone seen or heard of this problem before? It's driving me nuts
> > > :-)

The Quicksilver G4 has a CPU cooling arrangement that is VERY vulnerable
to dust. My friend had one, started giving her problems after a few
weeks. It kept getting worse and worse until she just bought a new
one. After several people pronounced the MoBo on her Quicksilver as
being dead, it made it's way to me, I was going to mod the case for
other purposes.

All I had to do to revive this "dead" Mac was to clean out the huge
accumulation of dust in between the CPU heatsink and the heat sink fan.
The design of the CPU cooling system draws in fresh air from outside the
case and blows it over the CPU heatsink. This air is not filtered in
any way. At the area of the interface between the fan and the heatsink,
dust coming in through the fan will tend to accumulate between the
heatsink fins, cutting off airflow to the heatsink. Remember that an
overheated CPU tends to generate seemingly random errors.

Lisa