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Re: Laptop randomly reboots

From: rhkramer@gmail.com
To: debian-user@lists.debian.org

On Tuesday, September 05, 2017 12:46:58 AM Sam Smith wrote:
> Well I guess I really spoke too soon.... Just got a random reboot a
> minute ago... Pretty much at a loss now. The only thing that hasn"t been
> replaced now is the CPU, battery, and power adapter. I do have a spare
> battery and power adapter. Guess I"ll try running with those for a month
> or so and see what happens. Though not really sure how either one of
> those would make the computer reboot randomly once a month. Laptop is
> mounted in a docking station. At least for the last 6 months, every
> reboot was while it was docked. But I do remember times last year
> sitting at the kitchen table undocked and getting a reboot so I don"t
> think the docking station is the issue.. But have no idea now :/

I haven"t paid much attention to this before today, but, if I had a problem
with unexplained reboots, the first area I"d look at is the power supply
"chain"--that is, the battery, the connections between the battery and the
laptop, power "glitches" to the house,etc.

I run a laptop with a known bad battery--if I disconnect the power supply it
crashes in seconds. OTOH, if your battery is good, it serves as a (long
lived) UPS--you should be able to ride out hours long power glitches.

If I had a known good battery, I might try examining the contacts between the
battery and the laptop--are they clean / shiny, is the "springy side" still
"springy", does the battery fit snugly in the case or is there enough clearance
for it to possibly move and break contact with the laptop? I might even try
picking up the laptop and reasonably gently shaking it (while running) to see
if it reboots. (You don"t want to shake it so hard that you damage something

If you have a known bad battery, I"d look at the chain from the power outlet
through the various cords and contacts on both sides of the power adapter.
Try shaking the power adapter.

Is the power to your house reliable--is there any chance you"ve had brief
power outages overnight? (In the US, most electric utilities have automatic
reclosers on the power line circuit breakers--if they detect a fault they
open, then try closing again after a few seconds (in hopes that either the
fault has cleared (maybe a shorting tree branch has either blown or burned),
away, open again if there is still a fault, again try to reclose, after a few
seconds. In most cases, they try this something like 3 times, with a somewhat
longer delay before the last retry.

Oh wait, you have (presumably known good) spare battery and power adapter--try

Power is not the only thing that will shutdown a laptop, but rebooting automatically
sounds a bit strange in itself.  Most I have seen take your input to power-up unless
a specific instruction is given to reboot.
Are you sure you have not set a hot-key for reboot?
Is it possible a fan or an overheating alarm is not shutting it off? But then again, you
are talking about a reboot not a shutdown.
Anything else from the manufacturer that is triggering a reboot?
If the operating system is at fault for ordering a reboot that will be in the logs.
If it is a mechanical shutdown it may be instant and not giving enough warnings
to the system to log anything.
So why is it rebooting?  Maybe it goes through an interruption that is not a shutdown
so instantly the system is trying to recuperate from the interruption.  Possibly insufficient
or too much voltage is going through a self protected circuit which causes the interruption
and then allows current back through again, giving you the illusion of a reboot.
Sometimes disk drives on their way out draw too much current, or cd/dvd drives, which
the power supply can't keep up with which cause an interruption till enough juice is
built up to get the motor rolling again.  It could be as simple a small capacitor in one of
the drives.  Do your drive/s go to sleep in some state to preserve power?  Look at your
power settings and turn off the energy conserving options.
Maybe boot from usb into a live system, disable the drives from the bios and run a
usb stick or drive.  If the problem comes up again then it is not drive related or operating
system related.  Operating systems are much more likely to freeze up than to order
an anauthorized shut/reboot.  I am willing to bet it is a mechanical/electric glitch and
not an OS problem.

Unless you have discovered a new black-hole in systemd  (rust never sleeps). ;)

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