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Date:      Sun, 15 Jan 2012 13:29:45 -0000
From:      "Dave" <dave@g8kbv.demon.co.uk>
To:        FreeBSD Mailing List <freebsd-questions@freebsd.org>
Subject:   Re: Probable Hardware Failure
Message-ID:  <4F12D4C9.29852.83B51E@dave.g8kbv.demon.co.uk>
In-Reply-To: <C5188F60-2B7B-4AA7-8270-A2153925AD2B@lafn.org>
References:  <C5188F60-2B7B-4AA7-8270-A2153925AD2B@lafn.org>

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On 14 Jan 2012 at 16:12, Doug Hardie wrote:

> I have a pretty old desktop that has been around quite awhile.  It has
> started periodic crashes.  No log messages.  However, the core status
> files all show "double fault".  I am confident this is a hardware
> issue, but is there any easy way to determine if its power or memory
> related?  Those are the primary candidates although memory is also
> possible.  We really need to replace the entire unit, but that might
> be a bit more salable if I can present convincing evidence of the
> cause of the problem.
> 

Doug.

First check the Power Supply voltages are correct, and not too noisy.  
You'll need a good DMM, and 'scope for that.

Then, Visually examine the motherboard.  Are any of the round can 
electrolytic cap's "Bulging" at the top, or showing some brown or green 
gunk leaking out from where they sit on the board.

Likewise, it's often worth checking the low voltage caps in the PSU too.  
CAUTION!  Lots of volts exist in places inside them, take care, leave it 
a few mins after unplugging before taking it apart.

If so, it's not uncommon, you'll need to re-cap the Mobo, and or the PSU.  
Chances are, it's just one particular make/type that has failed, so if 
the others look OK, just change the failed ones.  Get the same value and 
voltage, but if you can from a reputable manufaturer, Panasonic or some 
such.

NOTE!  It's not uncommon either, for some parts to be installed at 
manufature the wrong way round.  It's amazing they last as long as they 
do before letting go.  Also, at least one Mobo maker had the wrong 
polarity markings on the board.  In those cases, you'll need to "buzz 
out" the associated power rail, comparing the polarity of the suspect 
part, with it's copanions on the same power rail.

For some common Mobo's, if you google the model number, you'll find 
websites selling complete re-cap kits, or offering an exchange service.

This is A LOT more common, than failing RAM, but can present itself in 
many and varied ways, from corrupted display's, to systems that wont 
boot.  Laptops are not immune to this either.

Also, Hard Drives can "go funny" with age, not failing as such, but the 
surface getting corrupted so that the drives own logic cant always 
unscramble the mess to the OS's satisfaction.

Then, there is the situation (I had one recently) where a failing PSU, 
caused Hard Drive data corruption.

Mr Gibson's product "Spinrite" is the tool to use to fix that (and it 
did!)  Not free, but more than worth the weight of a CD, Floppy or USB 
stick in Gold!  But you'll need to make sure the Mobo and everything else 
is OK.   It also works on Floppy drives, if you "Just HAVE" to recover 
that data.   If you have a fleet of machines, you should have your own 
copy.   No affiliation, just a more than happy long term owner/user of 
that tool.   (www.grc.com)

I've resurected more than one "Sick" PC by following some or all of the  
above, there again, I can wield a soldering iron with the best of them, 
and have the test gear to hand to fault find these things, and a source 
of parts.   But it saves a shed load of money if you can afford the time 
to do it...

Hope something helps.

Best Regards.

Dave B.




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