More broken hardware

Declan. Moriarty declan.moriarty at ntlworld.ie
Tue Mar 4 01:51:43 PST 2003


On Tue, Mar 04, 2003 at 03:33:41PM +1100, Chris Jensen enlightened us thusly
> Sorry, a bit OT again, but people here seem to know their hardware so I'm not 
> sure where else to go.
> So now it seems I've solved the lockups, but now I've got a new problem. My 
> computer is suddlenly very sensitive to vibrations.
> I have a desk with one of those draws for the keyboard and the front of the 
> draw folds down. It's made of wood, so sometimes it folds down with a bit of 
> a thump, this thump is enough to lock the computer up.
> I know computer + vibrations = bad, but isn't my computer over reacting a bit?
> At first I thought anything could have a loose connection, but that doesn't 
> seem quite right as a reboot (by the reset button) fixed the machine fine, 
> surely a loose connection would still be a problem even after the reboot if 
> the vibration dislodged it?
> So where do I look for this one? I'm thinking power supply maybe, but I'd like 
> to be a bit surer before I start replacing hardware willy nilly.
> 
Try these. If it takes a thump, the offender is probably held in
position by gravity. 

Are all the cards fully in? Sometimes the cards can't get fully in
because the m/b is poorly positioned in the box. Ditto simms, dimms, or
whatever.

Second, ide cables: What happens here is that the Insulation
Displacement connectors loosen up or such like. Solution: Put them in a
vice (with parallel sides, and squeeze GENTLY to press it down and
tighten.

Third, dry joints. The problem is that poorly made or wrong temprature 
solder joints develop an internal resistance, and become poorly
conductive. The leg of a device (usually a device that is heat cycled)
becomes loose in the joint, and insulated from the solder, which is
insulated from it. I have been able to pull out 'soldered in' devices
because of dry joints. Cure - remove solder, scrape wire a bit and replace 
the solder with fresh. Adding fresh solder often suffices.

Find them by tapping around with the reverse(plastic) end of a screwdriver. 
Try this sort of thing: Unbolt your power supply, leave it connected, and
switch on. It's earthed, before everyone yells at me! You would need an
earth on your box, however. BTW, don't hot plug anything this way. With the 
power supply in your hand, you can thump it with the screwdriver, and see if 
your pc goes awol. Also tap around your m/b for a bit to try to narrow down 
the fault. Examine carefully any discoloured joint. 

At a guess, it's the power transistors/fets in the power supply.
The things on the heat sink to the uninitiated ;-)
-- 

	With best Regards,


	Declan Moriarty.
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