Unbelievable, 'sod's law' - power supply blows

Discussion in 'Compaq' started by poachedeggs, Dec 16, 2008.

  1. poachedeggs

    poachedeggs Guest

    I've had assistance here lately with my Deskpro EN SFF 886. I had
    been ignoring a sound like the hard drive switching itself on and off
    for a little while now and tonight it sems the power supply has
    blown. There was a small pop and a smell of burning and the green
    light's out for good, with a fuse change in the plug doing nothing. I
    can see a new supply will cost more than the machine, and there are no
    used ones on ebay at the moment that fit. I will asks the
    refurbishers to replace it but they are dodgy dealers who don't answer
    emails and I don't expect to get anywhere.

    I see there are 'no user-serviceable parts' inside these power
    supplies - haven't they got a simple fuse in to replace? - and I've
    heard rightly or wrongly that it's dangerous to open power supplies.
    But, is is likely that the power supply blowing has taken anything out
    with it? Like killing the motherboard? Because I've thought of
    moving the hard drive, RAM, DVD rom drive and floppy drive to
    something else, there being a few shops a short walk away that have
    used and custom systems. What do you think? Should I be hopeful (I
    will see if they have salvaged the same power supply first).

    I was in the middle of giving the machine a new lease of life by
    installing Linux Mint 2.2 (an Ubuntu derivative from only a few years
    back that suited the spec very well), which looked good when viewing
    the live CD and would get me round the problem of not being able to
    use smooth fonts after much googling and experimentation, so I am
    peeved after getting round a few problems with this machine that it
    has blown. Worse, a cheque I've been waiting for for sixteen months
    arrived this morning and is now probably earmarked for other things...
    sigh.

    Thanks in advance for any opinions, advice, suggestions, non-malicious
    laughter, etc.
     
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  2. Ben Myers

    Ben Myers Guest

    poachedeggs wrote:
    > I've had assistance here lately with my Deskpro EN SFF 886. I had
    > been ignoring a sound like the hard drive switching itself on and off
    > for a little while now and tonight it sems the power supply has
    > blown. There was a small pop and a smell of burning and the green
    > light's out for good, with a fuse change in the plug doing nothing. I
    > can see a new supply will cost more than the machine, and there are no
    > used ones on ebay at the moment that fit. I will asks the
    > refurbishers to replace it but they are dodgy dealers who don't answer
    > emails and I don't expect to get anywhere.
    >
    > I see there are 'no user-serviceable parts' inside these power
    > supplies - haven't they got a simple fuse in to replace? - and I've
    > heard rightly or wrongly that it's dangerous to open power supplies.
    > But, is is likely that the power supply blowing has taken anything out
    > with it? Like killing the motherboard? Because I've thought of
    > moving the hard drive, RAM, DVD rom drive and floppy drive to
    > something else, there being a few shops a short walk away that have
    > used and custom systems. What do you think? Should I be hopeful (I
    > will see if they have salvaged the same power supply first).
    >
    > I was in the middle of giving the machine a new lease of life by
    > installing Linux Mint 2.2 (an Ubuntu derivative from only a few years
    > back that suited the spec very well), which looked good when viewing
    > the live CD and would get me round the problem of not being able to
    > use smooth fonts after much googling and experimentation, so I am
    > peeved after getting round a few problems with this machine that it
    > has blown. Worse, a cheque I've been waiting for for sixteen months
    > arrived this morning and is now probably earmarked for other things...
    > sigh.
    >
    > Thanks in advance for any opinions, advice, suggestions, non-malicious
    > laughter, etc.


    The usual replacement for a power supply is another power supply. A few
    years ago, I opened up a custom power supply and replaced its fan,
    because Compaq (or a 3rd party parts house) would charge over $US100 for
    one... Ben Myers
     
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  3. Hi!

    > There was a small pop and a smell of burning and the green
    > light's out for good, with a fuse change in the plug doing nothing.


    In a word, "oops".

    Changing the fuse won't fix it--you've probably lost one of the switching
    transistors in the power supply.

    It's probably time to start looking for another system.

    > I see there are 'no user-serviceable parts' inside these power
    > supplies - haven't they got a simple fuse in to replace?


    Yes and no. I'm sure there is a protective fuse in the supply itself, or
    something very similar in function. But the fuse isn't what will be wrong,
    and replacing may only lead to more spectacular failures. You need to find
    out why the fuse blew. Some of this will be obvious--burnt and obliterated
    parts will show up. What caused those parts to fail may not be easy to find,
    as the truly defective part may not have blown up.

    As to the no-user-serviceable parts...well, the parts inside are serviceable
    if you can find replacements and know how to solder without making a mess
    and hurting yourself. You might actually stand a pretty fair chance of
    getting parts like capacitors, diodes and maybe even the main switching
    transistors. If you've lost a transformer, some coils, strange looking
    unmarked parts that you have no idea what they are, or the controller IC is
    fried...then you're probably out of luck. PC power supplies aren't
    particularly easy to fix, mainly because service literature isn't usually
    available in detailed enough form. Compaq most likely replaced these
    supplies as a whole unit and I doubt they ever did any repairs on bad ones
    that came back. If you have some experience, can find the controller IC
    datasheet, don't mind spending a few bucks on the most likely to be bad
    parts and can accept the fact that you might not be able to fix it...sure,
    why not? Should you try to fix it, don't go plugging it into the computer to
    test it. Rig up a dummy load that is made of things you won't feel bad about
    if they get blown up!

    There's not much to be afraid of in a dead PSU, so long as it isn't plugged
    in. You can certainly look inside without hurting yourself. The only thing
    to really be careful of are the (usually two) main filter capacitors in the
    supply. They can hold a charge, although it should dissipate within a few
    hours to a few days.

    > But, is is likely that the power supply blowing has taken anything out
    > with it? Like killing the motherboard? Because I've thought of
    > moving the hard drive, RAM, DVD rom drive and floppy drive to
    > something else, there being a few shops a short walk away that have
    > used and custom systems. What do you think?


    PC power supplies are supposed to shut down (hopefully nonviolently!) in the
    event of a fault. They have controllers inside that should see to this, if
    they've been properly designed and specified. This doesn't always
    happen--sometimes because the power supply was poorly designed, and
    sometimes because the failure was so catastrophic that nothing would have
    stopped other parts from being fried. In all likelihood, the remaining parts
    you have are fine. I wouldn't be surprised if the system came right back to
    life immediately with a replacement power supply.

    William
     
  4. poachedeggs

    poachedeggs Guest

    I don't know dangerous this was, but a visitor just now says the pink
    voltage switch on the psu isn't in the right position and then pointed
    at my very long guitar nails. Could I have knocked it with them while
    replacing the cord, we wonder in mild horror. In which case, maybe
    the rest of the pc's fine? I've been looking at generic power
    supplies, though their wattage is two or three times higher - are
    these no good? Some are very affordable to me, ten quid. Is the odd
    size of the Compaq EN SFF a factor or should a generic one fit?

    Thanks for more feedback you two. (I've naively or otherwise asked in
    a pc-building group about whether I can transplant everything into a
    new case/psu too.)


    On Dec 17, 12:30 am, "William R. Walsh"
    <> wrote:
    > Hi!
    >
    > > There was a small pop and a smell of burning and the green
    > > light's out for good, with a fuse change in the plug doing nothing.

    >
    > In a word, "oops".
    >
    > Changing the fuse won't fix it--you've probably lost one of the switching
    > transistors in the power supply.
    >
    > It's probably time to start looking for another system.
    >
    > > I see there are 'no user-serviceable parts' inside these power
    > > supplies - haven't they got a simple fuse in to replace?

    >
    > Yes and no. I'm sure there is a protective fuse in the supply itself, or
    > something very similar in function. But the fuse isn't what will be wrong,
    > and replacing may only lead to more spectacular failures. You need to find
    > out why the fuse blew. Some of this will be obvious--burnt and obliterated
    > parts will show up. What caused those parts to fail may not be easy to find,
    > as the truly defective part may not have blown up.
    >
    > As to the no-user-serviceable parts...well, the parts inside are serviceable
    > if you can find replacements and know how to solder without making a mess
    > and hurting yourself. You might actually stand a pretty fair chance of
    > getting parts like capacitors, diodes and maybe even the main switching
    > transistors. If you've lost a transformer, some coils, strange looking
    > unmarked parts that you have no idea what they are, or the controller IC is
    > fried...then you're probably out of luck. PC power supplies aren't
    > particularly easy to fix, mainly because service literature isn't usually
    > available in detailed enough form. Compaq most likely replaced these
    > supplies as a whole unit and I doubt they ever did any repairs on bad ones
    > that came back. If you have some experience, can find the controller IC
    > datasheet, don't mind spending a few bucks on the most likely to be bad
    > parts and can accept the fact that you might not be able to fix it...sure,
    > why not? Should you try to fix it, don't go plugging it into the computerto
    > test it. Rig up a dummy load that is made of things you won't feel bad about
    > if they get blown up!
    >
    > There's not much to be afraid of in a dead PSU, so long as it isn't plugged
    > in. You can certainly look inside without hurting yourself. The only thing
    > to really be careful of are the (usually two) main filter capacitors in the
    > supply. They can hold a charge, although it should dissipate within a few
    > hours to a few days.
    >
    > > But, is is likely that the power supply blowing has taken anything out
    > > with it?  Like killing the motherboard?  Because I've thought of
    > > moving the hard drive, RAM, DVD rom drive and floppy drive to
    > > something else, there being a few shops a short walk away that have
    > > used and custom systems.  What do you think?

    >
    > PC power supplies are supposed to shut down (hopefully nonviolently!) in the
    > event of a fault. They have controllers inside that should see to this, if
    > they've been properly designed and specified. This doesn't always
    > happen--sometimes because the power supply was poorly designed, and
    > sometimes because the failure was so catastrophic that nothing would have
    > stopped other parts from being fried. In all likelihood, the remaining parts
    > you have are fine. I wouldn't be surprised if the system came right back to
    > life immediately with a replacement power supply.
    >
    > William
     
  5. Ben Myers

    Ben Myers Guest

    poachedeggs wrote:
    > I don't know dangerous this was, but a visitor just now says the pink
    > voltage switch on the psu isn't in the right position and then pointed
    > at my very long guitar nails. Could I have knocked it with them while
    > replacing the cord, we wonder in mild horror. In which case, maybe
    > the rest of the pc's fine? I've been looking at generic power
    > supplies, though their wattage is two or three times higher - are
    > these no good? Some are very affordable to me, ten quid. Is the odd
    > size of the Compaq EN SFF a factor or should a generic one fit?
    >
    > Thanks for more feedback you two. (I've naively or otherwise asked in
    > a pc-building group about whether I can transplant everything into a
    > new case/psu too.)
    >
    >

    <SNIP>

    Well, if the voltage setting was incorrect, then the PSU was receiving
    220-240v when it was expecting 110-120v. That would burn it out for
    sure, and with double the voltage, I do not hold much hope for the
    motherboard either. The Compaq EN SFF uses a VERY much custom PSU.
    Different shape and different power connector than the usual 20-pin ATX
    PSU used with a Pentium 3... Ben Myers
     
  6. Guest

    On Dec 16, 8:17 pm, poachedeggs <> wrote:
    > I don't know dangerous this was, but a visitor just now says the pink
    > voltage switch on the psu isn't in the right position and then pointed
    > at my very long guitar nails.  Could I have knocked it with them while
    > replacing the cord, we wonder in mild horror.  


    If a switch was in 220, then a 220 supply was only getting 120
    volts. That would not harm the supply; would only cause a supply to
    not power. 120 volts does not harm 220 volt electronics. However, if
    the switch was changed when the supply was connected to AC mains, then
    damage may result.

    Switch is not easily changed by accident.

    If smoke came out, a fuse will not correct the defect.
     
  7. Hi!

    > Could I have knocked it with them while replacing
    > the cord, we wonder in mild horror. In which case,
    > maybe the rest of the pc's fine?


    Such a mishap would be unlikely, but possible. The voltage selector
    switches are generally not that easy to move. The number that is
    visible should be the voltage that the supply is set to operate on.

    If the supply was set to 110/120 volts and got 220/240, then the
    results are usually impressive and the supply will be burnt.

    Chances for survival are much better if the supply was set to 220/240
    and got 110/120 volts, although I have seen one supply die from that
    in a PS/2 Model 25 286 some years back.

    > I've been looking at generic power supplies, though
    > their wattage is two or three times higher - are
    > these no good?


    If they're truly capable of the specified wattage, they'll be fine.
    (See below.) However, the Compaq Deskpro SFF systems do not use a
    standard ATX connector.

    You might get it running if you can figure out the pinout and splice
    wires, but the PSU you find probably won't fit in the case (unless you
    get a small one, which can be done). It would have been much easier to
    do this with the power supply working, although wire color can
    sometimes give a hint.

    > Some are very affordable to me, ten quid.


    You should look for something better. Let's see what a cheap power
    supply looks like inside:

    http://greyghost.mooo.com/psuthoughts/

    > (I've naively or otherwise asked in a pc-building
    > group about whether I can transplant everything
    > into a new case/psu too.)


    I don't think it will work...the fullsize Deskpro parts might make the
    transition because they are more or less ATX shaped. The Deskpro SFF
    parts are engineered to work in just one case--the Deskpro SFF case.
    They're not a standard shape or size.

    If you want to build a computer at a low cost, I would recommend
    looking at an inexpensive case and something like the motherboards I
    reviewed in the links below if you don't need lots and lots of
    computing power:

    http://greyghost.mooo.com/intelatom/
    http://greyghost.mooo.com/d201gly2/

    The current generation of the Intel D945GCLF2 board is the D945GCLF2,
    which has an improved processor. I bought one recently. I still need
    to review it.

    William
     
  8. Ben Myers

    Ben Myers Guest

    William R. Walsh wrote:
    > Hi!
    >
    >> Could I have knocked it with them while replacing
    >> the cord, we wonder in mild horror. In which case,
    >> maybe the rest of the pc's fine?

    >
    > Such a mishap would be unlikely, but possible. The voltage selector
    > switches are generally not that easy to move. The number that is
    > visible should be the voltage that the supply is set to operate on.
    >
    > If the supply was set to 110/120 volts and got 220/240, then the
    > results are usually impressive and the supply will be burnt.
    >
    > Chances for survival are much better if the supply was set to 220/240
    > and got 110/120 volts, although I have seen one supply die from that
    > in a PS/2 Model 25 286 some years back.
    >
    >> I've been looking at generic power supplies, though
    >> their wattage is two or three times higher - are
    >> these no good?

    >
    > If they're truly capable of the specified wattage, they'll be fine.
    > (See below.) However, the Compaq Deskpro SFF systems do not use a
    > standard ATX connector.
    >
    > You might get it running if you can figure out the pinout and splice
    > wires, but the PSU you find probably won't fit in the case (unless you
    > get a small one, which can be done). It would have been much easier to
    > do this with the power supply working, although wire color can
    > sometimes give a hint.
    >
    >> Some are very affordable to me, ten quid.

    >
    > You should look for something better. Let's see what a cheap power
    > supply looks like inside:
    >
    > http://greyghost.mooo.com/psuthoughts/
    >
    >> (I've naively or otherwise asked in a pc-building
    >> group about whether I can transplant everything
    >> into a new case/psu too.)

    >
    > I don't think it will work...the fullsize Deskpro parts might make the
    > transition because they are more or less ATX shaped. The Deskpro SFF
    > parts are engineered to work in just one case--the Deskpro SFF case.
    > They're not a standard shape or size.
    >
    > If you want to build a computer at a low cost, I would recommend
    > looking at an inexpensive case and something like the motherboards I
    > reviewed in the links below if you don't need lots and lots of
    > computing power:
    >
    > http://greyghost.mooo.com/intelatom/
    > http://greyghost.mooo.com/d201gly2/
    >
    > The current generation of the Intel D945GCLF2 board is the D945GCLF2,
    > which has an improved processor. I bought one recently. I still need
    > to review it.
    >
    > William


    Surprise! Some of the desktop models of the Compaq Socket 370 DeskPros
    use a custom 24-pin power supply, a forerunner of the newer 24-pinners,
    no doubt. Standard ATX size, though.

    If someone is really in love with a Compaq DeskPro desktop case, I
    suppose another motherboard could be put inside, along with another
    power supply and a rewiring of the leads to the front panel (on-off
    switch, power LED, HDD LED). It's not a bad looking case, but beige has
    fallen out of favor lately... Ben Myers
     
  9. Hi!

    > Surprise! Some of the desktop models of the Compaq
    > Socket 370 DeskPros use a custom 24-pin power supply,
    > a forerunner of the newer 24-pinners, no doubt.


    I wasn't sure, but I figured something like that might be happening.
    Still, I'd have to think (and maybe one of these days I'll find out)
    that a person inclined to take the time could rearrange the pins in a
    standard ATX supply to make it work. Compaq couldn't have been too
    creative with the voltages.

    > If someone is really in love with a Compaq DeskPro
    > desktop case


    It's a nice case...they actually used fairly decent steel for it. The
    SFF Deskpro systems are not quite as sturdy, but they'll do. I see
    things getting cheaper (thinner metal) into the Evo D500 and D510 SFF
    boxen, up to the later "HPaq" models where they became almost totally
    generic.

    I got a Compaq Presario S4020WM tower that came to me with a blown
    Bestec PSU and motherboard. It seemed like too nice of a case to throw
    away, so I slapped a Biostar P4M900-M4 motherboard and a Socket 478
    Northwoods P4 into it along with a working power supply. It needed
    some wiring adaptation for the power LED, HDD LED and the power button
    to be functional.

    William
     
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