Weird smell from new power supply after power down.

Archived from groups: alt.comp.hardware.homebuilt (More info?)

I just built a new system (A8V motherboard, athlon 3400, 2 gigs ram)
and put in a new 420 watt power supply. (diablotek ATX)

The system works fine, but when I power down and don't turn off the
power switch on the power supply, I get a weird smell after a few
minutes, as if something was overheating. I can't feel anything
giving off heat (but it might be inside the power supply). So, for the
time being, I just turn off the power switch after system shutdown.

Everything works great while running, but this problem has me worried.

I think I hooked everything up ok, but my guess is that I did
something wrong and it's drawing too much 12v power while off. I don't
have a meter to test this, so I'm only guessing.

I did turn off "wake on LAN" in the Bios, but that made no difference.

Anyone have any idea what is going on here?
Thanks!

Chris
10 answers Last reply
More about weird smell power supply power down
  1. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    "Chris J..." wrote:

    > I just built a new system (A8V motherboard, athlon 3400, 2 gigs ram)
    > and put in a new 420 watt power supply. (diablotek ATX)
    >
    > The system works fine, but when I power down and don't turn off the
    > power switch on the power supply, I get a weird smell after a few
    > minutes, as if something was overheating. I can't feel anything
    > giving off heat (but it might be inside the power supply). So, for the
    > time being, I just turn off the power switch after system shutdown.
    >
    > Everything works great while running, but this problem has me worried.
    >
    > I think I hooked everything up ok, but my guess is that I did
    > something wrong and it's drawing too much 12v power while off. I don't
    > have a meter to test this, so I'm only guessing.
    >
    > I did turn off "wake on LAN" in the Bios, but that made no difference.
    >
    > Anyone have any idea what is going on here?

    Perhaps as innocent as something on a HR or power resistor in the +5vsb
    circuit. With no fan (and increased power requirements) the +5vsb often
    gets very hot when the system is powered off.

    BTW, when the unit is powered off, there is NO 12v power - only +5vsb.
  2. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Fri, 04 Mar 2005 21:17:52 -0800, ric <nospam@home.com> wrote:

    >"Chris J..." wrote:
    >
    >> I just built a new system (A8V motherboard, athlon 3400, 2 gigs ram)
    >> and put in a new 420 watt power supply. (diablotek ATX)
    >>
    >> The system works fine, but when I power down and don't turn off the
    >> power switch on the power supply, I get a weird smell after a few
    >> minutes, as if something was overheating. I can't feel anything
    >> giving off heat (but it might be inside the power supply). So, for the
    >> time being, I just turn off the power switch after system shutdown.
    >>
    >> Everything works great while running, but this problem has me worried.
    >>
    >> I think I hooked everything up ok, but my guess is that I did
    >> something wrong and it's drawing too much 12v power while off. I don't
    >> have a meter to test this, so I'm only guessing.
    >>
    >> I did turn off "wake on LAN" in the Bios, but that made no difference.
    >>
    >> Anyone have any idea what is going on here?
    >
    >Perhaps as innocent as something on a HR or power resistor in the +5vsb
    >circuit. With no fan (and increased power requirements) the +5vsb often
    >gets very hot when the system is powered off.

    It could well be something like that; I have not left the system
    powered down without turning off the power manually for more than a
    couple of minutes, so it may just be something that will go away?

    BTW, Could someone explain to me why there is a need for power once
    the system is off? I know the power button circuit would need some,
    but it seems a bit of a waste to have the system using power while off
    if there isn't a reason?

    >BTW, when the unit is powered off, there is NO 12v power - only +5vsb.

    Thanks... I was thinking of the 12v connector on the MB and wrongly
    assumed that meant it was 12v power when off. .

    Thanks!
  3. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Fri, 04 Mar 2005 21:42:14 -0700, Chris J...
    <chris@noadresss.com> wrote:

    >I just built a new system (A8V motherboard, athlon 3400, 2 gigs ram)
    >and put in a new 420 watt power supply. (diablotek ATX)

    Is it a decent unit or a questionable generic?
    I've seen plenty of pseudo-420W PSU that wouldn't be
    sufficient for your system, but the typical decent 420W
    would be fine.

    >
    >The system works fine, but when I power down and don't turn off the
    >power switch on the power supply, I get a weird smell after a few
    >minutes, as if something was overheating. I can't feel anything
    >giving off heat (but it might be inside the power supply). So, for the
    >time being, I just turn off the power switch after system shutdown.

    Perhaps the supply is adequate but note that one pushed ot
    produce more power than the design can sustain long-term,
    will not last for as long a term. Some may run for a few
    days, weeks, months. Hate to plant the seed of doubt but
    "Diablotech" sure it's very inspiring.

    >
    >Everything works great while running, but this problem has me worried.
    >
    >I think I hooked everything up ok, but my guess is that I did
    >something wrong and it's drawing too much 12v power while off. I don't
    >have a meter to test this, so I'm only guessing.
    >
    >I did turn off "wake on LAN" in the Bios, but that made no difference.
    >
    >Anyone have any idea what is going on here?
    >Thanks!

    As Ric mentioned it owuld be 5VSB power being used. Check
    your motherboard manual for the locations of 5VSB jumpers on
    the motherboard. There might be one per PS2 ports and one
    per each pair of USB ports and each USB pin-header. By
    jumpering them to 5V rather than 5VSB you could be
    significantly reducing the 5VSB current during that soft-off
    state of the system.

    You could also take 5VSB voltage readings with a multimeter
    to see if it's at least at 5V.
  4. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Sat, 05 Mar 2005 06:56:20 GMT, kony <spam@spam.com> wrote:

    >On Fri, 04 Mar 2005 21:42:14 -0700, Chris J...
    ><chris@noadresss.com> wrote:
    >
    >>I just built a new system (A8V motherboard, athlon 3400, 2 gigs ram)
    >>and put in a new 420 watt power supply. (diablotek ATX)
    >
    >Is it a decent unit or a questionable generic?

    My best guess is questionable generic. I bought it online with the
    other components, and it was all of $30. What attracted me to it was
    that it was rated as very quiet, had two variable rate fans, and a
    power port on the back like power supplies did before ATX.

    I know I should have done more research before buying, and usually do,
    but this was a no-notice rebuild; my old system died, and I needed the
    new system fast. I had about an hour to pick a CPU, MB, and other
    components before the shipping cut-off time, so concentrated on
    researching motherboards and CPU's. (I needed to get it the next day,
    which was a Friday).

    >I've seen plenty of pseudo-420W PSU that wouldn't be
    >sufficient for your system, but the typical decent 420W
    >would be fine.

    But wouldn't that only be a problem with the system on? This problem
    only occurs after it's off.

    >>The system works fine, but when I power down and don't turn off the
    >>power switch on the power supply, I get a weird smell after a few
    >>minutes, as if something was overheating. I can't feel anything
    >>giving off heat (but it might be inside the power supply). So, for the
    >>time being, I just turn off the power switch after system shutdown.
    >
    >Perhaps the supply is adequate but note that one pushed ot
    >produce more power than the design can sustain long-term,
    >will not last for as long a term. Some may run for a few
    >days, weeks, months. Hate to plant the seed of doubt but
    >"Diablotech" sure it's very inspiring.

    I've had doubts ever since I received it, and it had no instructions
    or literature whatsoever in the box.

    >>I did turn off "wake on LAN" in the Bios, but that made no difference.
    >>
    >>Anyone have any idea what is going on here?
    >>Thanks!
    >
    >As Ric mentioned it owuld be 5VSB power being used. Check
    >your motherboard manual for the locations of 5VSB jumpers on
    >the motherboard. There might be one per PS2 ports and one
    >per each pair of USB ports and each USB pin-header. By
    >jumpering them to 5V rather than 5VSB you could be
    >significantly reducing the 5VSB current during that soft-off
    >state of the system.

    I just checked the manual and the computer;
    all four USB-headers are jumpered to 5v, and the keyboard (PS2) is the
    same. They have been this way all along. Is this how they should be to
    reduce the power load? I don't have any need that I know of for USB
    power while off.

    The power supply is rated at 2A for 5VSB, and looks like
    -5v at .5A

    I'd like to try setting the PS2 to +5VSB so I could try the
    keyboard-on feature, but I'll wait on that if it's going to use more
    power (and I seem to have a power problem as it is).

    >You could also take 5VSB voltage readings with a multimeter
    >to see if it's at least at 5V.

    I'll get a multi meter this weekend (the one I have is dead) and try
    that, thanks!

    Errr, I've got to ask a dumb question here, but where, exactly, should
    the reading be taken? At the jumper pins? Or the USB pins?
    Or somewhere else?

    Thanks!
  5. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    In article <maci215u3gt8iki0tl2i0qvga079unf9jo@4ax.com>, Chris J...
    says...
    > I just built a new system (A8V motherboard, athlon 3400, 2 gigs ram)
    > and put in a new 420 watt power supply. (diablotek ATX)
    >
    > The system works fine, but when I power down and don't turn off the
    > power switch on the power supply, I get a weird smell after a few
    > minutes, as if something was overheating. I can't feel anything
    > giving off heat (but it might be inside the power supply). So, for the
    > time being, I just turn off the power switch after system shutdown.
    >
    > Everything works great while running, but this problem has me worried.
    >
    Possibly the laquer burning off some of the components. New boards
    always seem to have that "new car" smell for a little while.


    --
    Conor

    An imperfect plan executed violently is far superior to a perfect plan.
    -- George Patton
  6. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Sat, 05 Mar 2005 02:14:46 -0700, Chris J...
    <chris@noadresss.com> wrote:


    >>I've seen plenty of pseudo-420W PSU that wouldn't be
    >>sufficient for your system, but the typical decent 420W
    >>would be fine.
    >
    >But wouldn't that only be a problem with the system on? This problem
    >only occurs after it's off.

    Often no, a better power supply would tend to be comprised
    of better sub-circuits including the 5VSB supply portion.


    >I just checked the manual and the computer;
    >all four USB-headers are jumpered to 5v, and the keyboard (PS2) is the
    >same. They have been this way all along. Is this how they should be to
    >reduce the power load?

    Yes

    >I don't have any need that I know of for USB
    >power while off.
    >
    >The power supply is rated at 2A for 5VSB, and looks like
    >-5v at .5A

    -5V is irrelevant, the 5VSB circuit is the one active while
    system is "off" but still plugged to AC.

    >
    >I'd like to try setting the PS2 to +5VSB so I could try the
    >keyboard-on feature, but I'll wait on that if it's going to use more
    >power (and I seem to have a power problem as it is).

    You might as well try it, if that's what you want then
    there's no sense being a slave to a generic PSU that might
    fail in other ways regardless of the 5VSB.

    >
    >>You could also take 5VSB voltage readings with a multimeter
    >>to see if it's at least at 5V.
    >
    >I'll get a multi meter this weekend (the one I have is dead) and try
    >that, thanks!
    >
    >Errr, I've got to ask a dumb question here, but where, exactly, should
    >the reading be taken? At the jumper pins? Or the USB pins?
    >Or somewhere else?

    Reading could be taken at USB pins to troubleshoot USB
    related anomolies but in this case you may as well probe in
    though the back of the ATX connector, while plugged into the
    motherboard, system off (but still plugged into AC of
    course). Ground would ideally be ATX gound connector but
    any (case) metal gound point should suffice for this
    reading, so long as it's not clear-coated or otherwise
    painted and thus there is no voltage reading at all.
  7. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Sat, 05 Mar 2005 11:57:17 GMT, kony <spam@spam.com> wrote:

    >On Sat, 05 Mar 2005 02:14:46 -0700, Chris J...
    ><chris@noadresss.com> wrote:
    >
    >
    >>>I've seen plenty of pseudo-420W PSU that wouldn't be
    >>>sufficient for your system, but the typical decent 420W
    >>>would be fine.
    >>
    >>But wouldn't that only be a problem with the system on? This problem
    >>only occurs after it's off.
    >
    >Often no, a better power supply would tend to be comprised
    >of better sub-circuits including the 5VSB supply portion.

    Thanks... I'm considering replacing it at this point, with one by
    Antek.

    >>I don't have any need that I know of for USB
    >>power while off.
    >>
    >>The power supply is rated at 2A for 5VSB, and looks like
    >>-5v at .5A
    >
    >-5V is irrelevant, the 5VSB circuit is the one active while
    >system is "off" but still plugged to AC.

    So, if I understand right, the only thing using power with all the
    jumpers set to 5V should be the LED and the circuit for the power
    switch?

    >>I'd like to try setting the PS2 to +5VSB so I could try the
    >>keyboard-on feature, but I'll wait on that if it's going to use more
    >>power (and I seem to have a power problem as it is).
    >
    >You might as well try it, if that's what you want then
    >there's no sense being a slave to a generic PSU that might
    >fail in other ways regardless of the 5VSB.

    Good point. I'll try it, thanks.

    >>Errr, I've got to ask a dumb question here, but where, exactly, should
    >>the reading be taken? At the jumper pins? Or the USB pins?
    >>Or somewhere else?
    >
    >Reading could be taken at USB pins to troubleshoot USB
    >related anomolies but in this case you may as well probe in
    >though the back of the ATX connector, while plugged into the
    >motherboard, system off (but still plugged into AC of
    >course). Ground would ideally be ATX gound connector but
    >any (case) metal gound point should suffice for this
    >reading, so long as it's not clear-coated or otherwise
    >painted and thus there is no voltage reading at all.

    Thanks... I'll try it as soon as I get the new multimeter.
  8. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Sat, 5 Mar 2005 11:24:12 -0000, Conor <conor@conorturton.com>
    wrote:

    >In article <maci215u3gt8iki0tl2i0qvga079unf9jo@4ax.com>, Chris J...
    >says...
    >> I just built a new system (A8V motherboard, athlon 3400, 2 gigs ram)
    >> and put in a new 420 watt power supply. (diablotek ATX)
    >>
    >> The system works fine, but when I power down and don't turn off the
    >> power switch on the power supply, I get a weird smell after a few
    >> minutes, as if something was overheating. I can't feel anything
    >> giving off heat (but it might be inside the power supply). So, for the
    >> time being, I just turn off the power switch after system shutdown.
    >>
    >> Everything works great while running, but this problem has me worried.
    >>
    >Possibly the laquer burning off some of the components.

    Ahhh. That is what it smells like. Also, the smell is much fainter
    now, and yesterday I left it on for five minutes and it seemed to be
    going away, plus I couldn't find anything actually warm in the PS...

    If the worst thing I'm looking at is a power supply failure, I'll just
    go ahead and leave it on and see what happens.
    Thanks!
  9. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    "Chris J..." wrote:

    > >Perhaps as innocent as something on a HR or power resistor in the +5vsb
    > >circuit. With no fan (and increased power requirements) the +5vsb often
    > >gets very hot when the system is powered off.
    >
    > It could well be something like that; I have not left the system
    > powered down without turning off the power manually for more than a
    > couple of minutes, so it may just be something that will go away?

    Quite possibly, yes. But NOT 100% certain.
  10. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    Update:

    The problem appears to have solved itself. Thanks to the advice I
    received here, I was fairly sure that all I was risking was the power
    supply, so I went ahead and left it on after system shutdown. The
    smell returned, less this time, but after ten minutes was nearly gone.
    An hour later, nothing. Left it on all night, and booted fine, and no
    problems when i next powered down.

    Thanks everyone!
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