OT: vexing hw issue

Tim ignored_mailbox at yahoo.com.au
Sat Nov 13 00:15:26 UTC 2010


On Fri, 2010-11-12 at 13:24 -0800, Dave Stevens wrote:
> Any ideas? I mean ANY ideas, I'm out of clues on this one. References welcome.

Well, I'd start by careful disassembly and inspection for any loose
parts.  Then careful reassembly with the minimum of parts, turn on, and
observe.

Take anti-static precautions.  If you're not familiar with how and why,
here's a brief synopsis.

Electronic components are sensitive to static discharge.  It can damage
them instantly, or significantly weaken them that they will fail in a
few weeks, months, or years later.  By that time, you will not associate
the failure with what you did, some time ago.  It's not that they've
developed some charge, that's a problem; it's a sudden (enough) change,
that is.  So the key is to keep things at the same potential as
everything else.

If you ever wear clothes that cause static charges when you move about
(most of us have taken off a wooly jumper, and noticed that sort of
thing, at some stage in our life), those are exactly the sort of thing
that you don't want to be wearing while working with static-sensitive
parts.

If you do not have anti-static gear (slow discharge conductive desk mats
and floor mats, and wrist bands), then take the following sort of
precautions outlined below.  The anti-static gear is poorly conductive,
it will slowly drain away charges, all the time, so they can't build up.
And whenever something with a charge comes in contact, it doesn't
rapidly discharge.

Ground your computer.  Not by plugging it into the power, so you're
working on a live box, but by connecting it to something else that's
grounded.  e.g. The video monitor.

Do not ground yourself, ever.  It makes it very hard for you to break a
connection if you get an electric shock.  The anti-static wristbands
only have a poor conductive path, it discharges static, slowly, but
shouldn't be able to carry enough current to electrocute you if you put
your hands on something faulty, or in places that you shouldn't.  Though
tethering yourself to the desk does have the problem that if you move
away without unplugging, you can drag things off the desk.

Discharge yourself by touching your desk, it'll be the safest way to
rapidly discharge yourself without upsetting any static-sensitive parts.
Then touch your computer chassis, so that you're at the some potential
as your computer, and the parts.  Lean against it while you work on it,
so you stay with the same charge.  If you walk away, or move away
enough, you'll build up a charge.  Go through the discharge procedure
again before touching any electronics.

Leave your computer bits in their anti-static bags.  Put them in touch
with your computer before you take them out of their anti-static bags
(rest them on the case, somewhere).  While handling the parts, stay in
contact with your computer.  That keeps everything to the same
potential.

When it comes to removing parts, do something the same.  Take a board
out, rest it against the computer casing.  Put it in an anti-static bag
if you have one.  Hang onto these anti-static bags whenever you get any.

-- 
[tim at localhost ~]$ uname -r
2.6.27.25-78.2.56.fc9.i686

Don't send private replies to my address, the mailbox is ignored.  I
read messages from the public lists.





More information about the users mailing list