[GLLUG] dell computer

[Richard Houser]

When a power supply first fails, the machine typically WILL boot, but 
will be out of spec and slowly damage the rest of the machine as it's 
condition worsens.  Typically, a low end ($10-20) power supply tester 
will flag the really bad stuff before it starts damaging the rest of the 
hardware.  Out of 6 failed ATX supplies I still have around, 4 did POST 
and show video on some boards but had very unstable power levels below 
the rated specifications.

Testing the power supply takes about 60 seconds after either moving the 
case or the power supply to the tester and doesn't really carry a risk. 
  Pretending that it can't have a problem because the machine still 
boots has a very real risk to it.  The type of test you are referring to 
is useless for this type of determination.  The test is useful if you 
are unable to get the machine to power on but otherwise tells you 
nothing about the health of the power supply.

Often, an unstable power supply will get passed up by an inexperienced 
technician.  When you see a system that blows 4 motherboards, or two 
motherboards and a hard disk, it's a very likely bet (>85%) that the 
power supplied in that system is not clean and is actually causing the 
damage.  If you look at the higher end motherboards, you will notice an 
excess of large capacitors when compared to the cheaper boards that Dell 
uses.  That buys those boards a little more leeway when dealing with bad 
power, but eventually even that will cause a problem.

Fans typically don't just die either.  They are relatively simple bits 
of electronics and just wear out over time.  If you have a fan die on 
you, chances are that it wasn't working smoothly for a long time and was 
just neglected.  If the fan is connected via the motherboard, you are 
back to the possibility of a component feeding that power having failed 
(potentially due to damage from unstable power again).

Caleb Cushing wrote:
> being an ex dell warranty from what she's told me so far it isn't the 
> power supply. but I have to  look further. but generally you don't get 
> anything onscreen if the powersupply is dead. It's either the fan or the 
> mobo. I'm hoping fan. I've seen those die on the job. it worked when I 
> turned it of and wasn't working when I turned it back on.
> 
> On 5/10/07, *Richard Houser* <rick at divinesymphony.net 
> <mailto:rick at divinesymphony.net>> wrote:
> 
>     Dell is known for putting a lot of junk components into it's systems.
>     Usually, the motherboard and cases are highly proprietary and not worth
>     buying replacement parts for.  However, before you get to that point,
>     there is probably a lot of other stuff in that case worth salvaging even
>     if the motherboard is trashed.  At a minimum, you are probably talking a
>     CPU + heatsink combo, a P4 processor, a little bit of low-end RAM, an
>     optical drive (probably a CD-RW/DVD-ROM combo or a DVD writer), and a
>     hard disk.
> 
>     Could you bring the power supply tonight? (if you can't remove it
>     yourself, just bring the whole tower).  I've got a low-cost power
>     supply
>     tester we can plug into your machine to test the levels and flag any
>     obvious problems with it.  Overall, failed power supplies are probably
>     the single most common failure I've seen on low-end systems, and they
>     can cause damage to other electronics in the case.
> 
>     After you've tested the power supply, your second task needs to be
>     taking the cover off the case and powering it on where you can see the
>     CPU fan.  If it's spinning quickly and evenly, and the heatsink is
>     firmly attached to the board, you aren't going to be in any major risk
>     of damaging other components.  From there, you need to run a memory
>     tester like memtest86 overnight, then try to install an OS on it.  You
>     can download memtest ISO images from the Internet, but some Linux
>     distros like Mandriva 2006.0 (in 2007, memtest didn't work for me)
>     contain a copy of memtest86 off the initial cd/dvd boot menu.
> 
> 
> 
> 
>     Julie Code wrote:
>      > Hi guys,
>      >        Today when I went to take the trash out, there was a computer
>      > sitting in the dumpster.  A dell Demension desktop P4 4500.  I just
>      > plugged it in and the fans are moving and it beeps when i turn it
>     on and
>      > says processor fan not detected.  I think it may say something
>     about a
>      > mboard too but not sure.  I was wondering if anyone had a working
>      > motherboard that they'd be willing to sell me that i could put
>     into this
>      > machine.  I know the LCD monitor works that they threw away because I
>      > just plugged it into my other computer.  I talked to Caleb on the
>     IM and
>      > that is what he thinks is wrong with it.  I wonder if it was
>     someone who
>      > didnt know a whole lot about computers and got mad and just threw
>     it in
>      > the dumpster when it mayt be an easy fix?? Well, thanks for any
>     of your
>      > input you may have.
>      >
>      > Julie
>      >
>      >
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> 
> 
> 
> -- 
> Caleb Cushing