ATX Power Supply Questions

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

I'm working on a project where I need the ATX power supply to be *on* at
all times.

Some motherboards support power on after power loss, but the board I'm
using does not support this feature.

I know you can turn an ATX power supply on by bridging pin 15 and ground (I
*think it's 15, definitely the green wire on most supplies). My question
is will I do any damage to the board doing this, and will it actually power
on the board?
15 answers Last reply
More about power supply questions
  1. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    Peale wrote:
    > I'm working on a project where I need the ATX power supply to be *on* at
    > all times.
    >
    > Some motherboards support power on after power loss, but the board I'm
    > using does not support this feature.
    >
    > I know you can turn an ATX power supply on by bridging pin 15 and ground (I
    > *think it's 15, definitely the green wire on most supplies). My question
    > is will I do any damage to the board doing this, and will it actually power
    > on the board?
    Pin #14, as shown in this photo...
    http://www.burningissues.net/how_to/power/psu.htm
  2. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    Patrick <pberry26@yahoo.com> scrawled on the wall in
    news:3CCnc.541230$B81.10035992@twister.tampabay.rr.com:

    > Pin #14, as shown in this photo...
    > http://www.burningissues.net/how_to/power/psu.htm

    Yes, thank you. So will it work?
  3. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    Peale <nospam.apeale69@hotmail.com> scrawled on the wall in
    news:Xns94E565878A297nospamapeale69hotmai@130.81.64.196:

    > Patrick <pberry26@yahoo.com> scrawled on the wall in
    > news:3CCnc.541230$B81.10035992@twister.tampabay.rr.com:
    >
    >> Pin #14, as shown in this photo...
    >> http://www.burningissues.net/how_to/power/psu.htm
    >
    > Yes, thank you. So will it work?
    >

    Anyone?

    --
    Bush and Kerry should NOT be in office!
    Vote "None Of The Above" this coming election!
    Make your vote count! Get the clowns out!
  4. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    Peale wrote:

    > Peale <nospam.apeale69@hotmail.com> scrawled on the wall in
    > news:Xns94E565878A297nospamapeale69hotmai@130.81.64.196:
    >
    > > Patrick <pberry26@yahoo.com> scrawled on the wall in
    > > news:3CCnc.541230$B81.10035992@twister.tampabay.rr.com:
    > >
    > >> Pin #14, as shown in this photo...
    > >> http://www.burningissues.net/how_to/power/psu.htm
    > >
    > > Yes, thank you. So will it work?
    > >
    >
    > Anyone?

    As noted, shorting pin 14 of the PSU/MB connector to common *will*
    start the PSU. Whether or not your MB will boot depends on the MB.
    Some MBs have issues with PWR_GOOD timing when configured in this
    manner. Try it and see.
  5. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Wed, 12 May 2004 19:44:35 GMT, Peale <nospam.apeale69@hotmail.com>
    wrote:

    >Peale <nospam.apeale69@hotmail.com> scrawled on the wall in
    >news:Xns94E565878A297nospamapeale69hotmai@130.81.64.196:
    >
    >> Patrick <pberry26@yahoo.com> scrawled on the wall in
    >> news:3CCnc.541230$B81.10035992@twister.tampabay.rr.com:
    >>
    >>> Pin #14, as shown in this photo...
    >>> http://www.burningissues.net/how_to/power/psu.htm
    >>
    >> Yes, thank you. So will it work?
    >>
    >
    >Anyone?

    What do you mean, "will it work"?
    That was kinda the whole point of the link and modification, no?

    It's not particularly difficult to do, try it and see for yourself. The
    main problem might be if there's a very brief power disturbance, long
    enough to crash the system but short enough to not reset it, then the
    system will be stuck, crashed, instead of rebooting. If you really need
    always-on then consider using an UPS too, but of course NOT the UPS
    software since it can't very well turn the machine off if the power supply
    is rigged to stay on.
  6. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    kony <spam@spam.com> scrawled on the wall in
    news:ji65a0d8bahaudrm4r9ldtr10elruqg0v6@4ax.com:

    > On Wed, 12 May 2004 19:44:35 GMT, Peale <nospam.apeale69@hotmail.com>
    > wrote:
    >
    >>Peale <nospam.apeale69@hotmail.com> scrawled on the wall in
    >>news:Xns94E565878A297nospamapeale69hotmai@130.81.64.196:
    >>
    >>> Patrick <pberry26@yahoo.com> scrawled on the wall in
    >>> news:3CCnc.541230$B81.10035992@twister.tampabay.rr.com:
    >>>
    >>>> Pin #14, as shown in this photo...
    >>>> http://www.burningissues.net/how_to/power/psu.htm
    >>>
    >>> Yes, thank you. So will it work?
    >>>
    >>
    >>Anyone?
    >
    > What do you mean, "will it work"?
    > That was kinda the whole point of the link and modification, no?

    I know that it will turn the PS on. My question was if it would do any
    damage to the board if I did so.

    > It's not particularly difficult to do, try it and see for yourself.
    > The main problem might be if there's a very brief power disturbance,
    > long enough to crash the system but short enough to not reset it, then
    > the system will be stuck, crashed, instead of rebooting. If you
    > really need always-on then consider using an UPS too, but of course
    > NOT the UPS software since it can't very well turn the machine off if
    > the power supply is rigged to stay on.

    It's going into an arcade cabinet running MAME. I *can* use an AT board
    and power supply, but am very limited to how much speed I can use since
    very few AT boards are made these days. Hence, I have to use an ATX
    board.

    The system will be running DOS. It's also wired to a central switch
    which will turn on all the other things in the cabinet (marquee, arcade
    monitor, coin door lights) so if the PS is wired so it is on all the
    time, it won't matter.

    The cabinet is done with the exception of this one last piece, and I just
    want to get it right the first time, and not fry anything in the process.


    --
    Bush and Kerry should NOT be in office!
    Vote "None Of The Above" this coming election!
    Make your vote count! Get the clowns out!
  7. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Thu, 13 May 2004 14:12:07 GMT, Peale <nospam.apeale69@hotmail.com>
    wrote:


    >> What do you mean, "will it work"?
    >> That was kinda the whole point of the link and modification, no?
    >
    >I know that it will turn the PS on. My question was if it would do any
    >damage to the board if I did so.
    >


    No damage

    >> It's not particularly difficult to do, try it and see for yourself.
    >> The main problem might be if there's a very brief power disturbance,
    >> long enough to crash the system but short enough to not reset it, then
    >> the system will be stuck, crashed, instead of rebooting. If you
    >> really need always-on then consider using an UPS too, but of course
    >> NOT the UPS software since it can't very well turn the machine off if
    >> the power supply is rigged to stay on.
    >
    >It's going into an arcade cabinet running MAME. I *can* use an AT board
    >and power supply, but am very limited to how much speed I can use since
    >very few AT boards are made these days. Hence, I have to use an ATX
    >board.

    Is MAME really needing that much performance? Lower performance setups
    may also mean less heat, easier to cool, less airflow/dust/fan wear. I
    suppose it's irrelevant though, since you already have the parts you want
    to use.

    >
    >The system will be running DOS. It's also wired to a central switch
    >which will turn on all the other things in the cabinet (marquee, arcade
    >monitor, coin door lights) so if the PS is wired so it is on all the
    >time, it won't matter.
    >
    >The cabinet is done with the exception of this one last piece, and I just
    >want to get it right the first time, and not fry anything in the process.

    It won't fry anything. You can test this youself though, by attaching a
    load to the power supply (like a hard drive) then shorting the PS-On pin
    you can confirm that the voltage levels are correct... that's all a power
    supply is meant to do, supply those voltages within spec at varying
    load... after you get the whole thing setup you ought to again measure
    voltage levels to confirm that they're acceptable but it shouldn't be a
    problem, just being extra cautious.
  8. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    kony <spam@spam.com> scrawled on the wall in
    news:dh57a05c3om4gjpav0rl7fkli8g63aouao@4ax.com:

    >>It's going into an arcade cabinet running MAME. I *can* use an AT
    >>board and power supply, but am very limited to how much speed I can
    >>use since very few AT boards are made these days. Hence, I have to
    >>use an ATX board.
    >
    > Is MAME really needing that much performance? Lower performance

    I'm guessing you've never used Mame before.

    It depends on the game. Something like Pac-Man doesn't require much
    effort. A game like Mortal Kombat does.

    > setups may also mean less heat, easier to cool, less airflow/dust/fan
    > wear. I suppose it's irrelevant though, since you already have the
    > parts you want to use.

    I'm building a classics cabinet as well that houses a 486. But that one
    has an AT PS ;-)

    >>
    >>The system will be running DOS. It's also wired to a central switch
    >>which will turn on all the other things in the cabinet (marquee,
    >>arcade monitor, coin door lights) so if the PS is wired so it is on
    >>all the time, it won't matter.
    >>
    >>The cabinet is done with the exception of this one last piece, and I
    >>just want to get it right the first time, and not fry anything in the
    >>process.
    >
    > It won't fry anything. You can test this youself though, by attaching
    > a load to the power supply (like a hard drive) then shorting the PS-On
    > pin you can confirm that the voltage levels are correct... that's all
    > a power supply is meant to do, supply those voltages within spec at
    > varying load... after you get the whole thing setup you ought to again
    > measure voltage levels to confirm that they're acceptable but it
    > shouldn't be a problem, just being extra cautious.

    I know what they do, but since I only have just the one power supply, I
    wanted to make sure I wasn't going to screw anything up.

    Thanks for your replies!

    --
    Bush and Kerry should NOT be in office!
    Vote "None Of The Above" this coming election!
    Make your vote count! Get the clowns out!
  9. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    Might be easier to build a little adapter. I have seen an extension
    for the ATX 20 pin Plug like they use in taller Server Towers. Might
    be possible to just take one and rewire it a bit.

    There might be a power supply company that sells such a power supply
    or a kit to modify it.

    Might also be possible to rewrite the BIOS of a motherboard so it can
    never tun off. Maybe a BIOS with no special power features.


    >Peale wrote:
    >> I'm working on a project where I need the ATX power supply to be *on* at
    >> all times.
    >>
    >> Some motherboards support power on after power loss, but the board I'm
    >> using does not support this feature.
    >>
    >> I know you can turn an ATX power supply on by bridging pin 15 and ground (I
    >> *think it's 15, definitely the green wire on most supplies). My question
    >> is will I do any damage to the board doing this, and will it actually power
    >> on the board?
    >Pin #14, as shown in this photo...
    >http://www.burningissues.net/how_to/power/psu.htm
    >
  10. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Sun, 16 May 2004 22:48:27 -0500, Charles <LastBoyScout@whitehouse.gov>
    wrote:

    >Might be easier to build a little adapter. I have seen an extension
    >for the ATX 20 pin Plug like they use in taller Server Towers. Might
    >be possible to just take one and rewire it a bit.
    >
    >There might be a power supply company that sells such a power supply
    >or a kit to modify it.
    >
    >Might also be possible to rewrite the BIOS of a motherboard so it can
    >never tun off. Maybe a BIOS with no special power features.

    If easiest is the goal, easiest would be buying a tap splice at the local
    hardware store, using that to connect PS_On wire to ground near the PSU
    casing end of the wiring harness.

    http://www.trickcableandswitch.com/mall/flagtapsplice.asp
  11. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    Peale <nospam.apeale69@hotmail.com> scrawled on the wall in
    news:Xns94E4E49E29D13nospamapeale69hotmai@130.81.64.196:

    Thanks to everyone that responded.

    The solution turned out to not be bridging pin 14 and ground. That would
    turn on the power supply, but not make everything run correctly.

    I asked an electrical engineer friend, and he said to take a capacitor,
    about 16v and 10uf or so, and put it on the power on pins on the
    motherboard.

    Since a capacitor is shorted when not charged, and becomes open when it
    is, it is a perfect solution. Everything powers up instantaneously.

    And because the cap is so small, it discharges very quickly, so you can
    power cycle quickly, if you have to.


    --
    Bush and Kerry should NOT be in office!
    Vote "None Of The Above" this coming election!
    Make your vote count! Get the clowns out!
  12. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    > Bush and Kerry should NOT be in office!
    > Vote "None Of The Above" this coming election!
    > Make your vote count! Get the clowns out!

    So what clown should we replace them with? By law we must have some clown
    running things.
  13. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Sat, 26 Jun 2004 23:07:27 -0500, Bob Davis wrote:

    >> Bush and Kerry should NOT be in office!
    >> Vote "None Of The Above" this coming election!
    >> Make your vote count! Get the clowns out!
    >
    > So what clown should we replace them with? By law we must have some clown
    > running things.

    Actually, we have to have a bunch of clowns. And we do.:-)

    --
    Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
    http://mysite.verizon.net/res0exft/cpu.htm
  14. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    Is the collective noun for a bunch of clown a clot? - A clot of clowns
    sounds better than a bunch!

    "Wes Newell" <w.newell@TAKEOUTverizon.net> wrote in message
    news:pan.2004.06.27.07.57.42.908196@TAKEOUTverizon.net...
    > On Sat, 26 Jun 2004 23:07:27 -0500, Bob Davis wrote:
    >
    > >> Bush and Kerry should NOT be in office!
    > >> Vote "None Of The Above" this coming election!
    > >> Make your vote count! Get the clowns out!
    > >
    > > So what clown should we replace them with? By law we must have some
    clown
    > > running things.
    >
    > Actually, we have to have a bunch of clowns. And we do.:-)
    >
    > --
    > Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
    > http://mysite.verizon.net/res0exft/cpu.htm
  15. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Sun, 27 Jun 2004 07:56:23 GMT, Wes Newell
    <w.newell@TAKEOUTverizon.net> wrote:

    >On Sat, 26 Jun 2004 23:07:27 -0500, Bob Davis wrote:
    >
    >>> Bush and Kerry should NOT be in office!
    >>> Vote "None Of The Above" this coming election!
    >>> Make your vote count! Get the clowns out!
    >>
    >> So what clown should we replace them with? By law we must have some clown
    >> running things.
    >
    >Actually, we have to have a bunch of clowns. And we do.:-)


    What's important that OUR clowns do unto other clowns before they do
    unto us.


    Not exactly the golden rule is it ?

    ..... it's a beautiful thing ;)
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