Power Supplies

Discussion in 'A+ Certification' started by lizzieb, Mar 1, 2006.

  1. lizzieb

    lizzieb Guest

    Hi

    I got a PC in to repair and all that was happening was the fans were coming
    on and nothing else. It is a Packard Bell Imedia celeron 1.3ghz. So I
    thought I would try changing the power supply. It had a 215watt supply so
    tried it with a new 400watt PSU. Still just the fans
    coming on. So just in case the new PSU was duff I tried it with an old 100w
    PSU from an old Time machine and it worked perfectly! Tried it with a couple
    of other PSUs and none worked - only this old 100watt one!

    What am I do do? Puzzled too.

    Lizzieb
     
    lizzieb, Mar 1, 2006
    #1
    1. Advertising

  2. lizzieb

    lizzieb Guest

    I have just done what you suggested but the situation is just the same. I
    ran PC-Check through it and motherboard, ram and processor all passed. I
    can't see any blown caps either. I really don't like to give it back as
    repaired!!! But maybe I will have to with a warning.

    Lizzieb
    "Jeremy" <> wrote in message
    news:iQhNf.51739$%...
    > Check the motherboard for blown caps. If any are present replace
    > motherboard. If not, remove the motherboard from the case, place it on
    > something non-conductive, and power it on with just the power supply,
    > processor, and RAM. You can use a pen or other small metal object to turn
    > it on by shorting the power header. If the system power on, run memtest86
    > overnight just to be sure, the RAM is probably not your problem but it
    > never hurts to be sure.
    >
    > This is not the behavior of a properly working motherboard. I would
    > suspect strongly that the board is bad or something in the case is causing
    > a short. Are there any components that you forgot to hook up when you
    > used the 100W?
    >
    > Selling the customer the 100W PS may seem like an easy out but it is not
    > really a good fix.
    >
    > Thanks,
    >
    > Jeremy
    >
    > lizzieb wrote:
    >> Hi
    >>
    >> I got a PC in to repair and all that was happening was the fans were
    >> coming
    >> on and nothing else. It is a Packard Bell Imedia celeron 1.3ghz. So I
    >> thought I would try changing the power supply. It had a 215watt supply so
    >> tried it with a new 400watt PSU. Still just the fans
    >> coming on. So just in case the new PSU was duff I tried it with an old
    >> 100w PSU from an old Time machine and it worked perfectly! Tried it with
    >> a couple of other PSUs and none worked - only this old 100watt one!
    >>
    >> What am I do do? Puzzled too.
    >>
    >> Lizzieb
    >>
    >>
     
    lizzieb, Mar 1, 2006
    #2
    1. Advertising

  3. You mentioned "blown caps," so I'm thinking you're only looking for caps
    leaking electrolyte. Check the caps for bulging from expansion,
    particularly the tops of the caps. The tops of the caps should be flat,
    not dome shaped. *Be sure to remove the power supply and look at the
    caps underneath it.*

    I agree with Jeremy, that it sure sounds like a bad motherboard, and I
    definitely would NOT give it back with a warning and a 100W power supply.

    John


    lizzieb wrote:
    > I have just done what you suggested but the situation is just the same. I
    > ran PC-Check through it and motherboard, ram and processor all passed. I
    > can't see any blown caps either. I really don't like to give it back as
    > repaired!!! But maybe I will have to with a warning.
    >
    > Lizzieb
    > "Jeremy" <> wrote in message
    > news:iQhNf.51739$%...
    >
    >>Check the motherboard for blown caps. If any are present replace
    >>motherboard. If not, remove the motherboard from the case, place it on
    >>something non-conductive, and power it on with just the power supply,
    >>processor, and RAM. You can use a pen or other small metal object to turn
    >>it on by shorting the power header. If the system power on, run memtest86
    >>overnight just to be sure, the RAM is probably not your problem but it
    >>never hurts to be sure.
    >>
    >>This is not the behavior of a properly working motherboard. I would
    >>suspect strongly that the board is bad or something in the case is causing
    >>a short. Are there any components that you forgot to hook up when you
    >>used the 100W?
    >>
    >>Selling the customer the 100W PS may seem like an easy out but it is not
    >>really a good fix.
    >>
    >>Thanks,
    >>
    >>Jeremy
    >>
    >>lizzieb wrote:
    >>
    >>>Hi
    >>>
    >>>I got a PC in to repair and all that was happening was the fans were
    >>>coming
    >>>on and nothing else. It is a Packard Bell Imedia celeron 1.3ghz. So I
    >>>thought I would try changing the power supply. It had a 215watt supply so
    >>>tried it with a new 400watt PSU. Still just the fans
    >>>coming on. So just in case the new PSU was duff I tried it with an old
    >>>100w PSU from an old Time machine and it worked perfectly! Tried it with
    >>>a couple of other PSUs and none worked - only this old 100watt one!
    >>>
    >>>What am I do do? Puzzled too.
    >>>
    >>>Lizzieb
    >>>
    >>>

    >
    >
     
    WinXP_Powered, Mar 1, 2006
    #3
  4. lizzieb

    J. Clarke Guest

    lizzieb wrote:

    > I have just done what you suggested but the situation is just the same. I
    > ran PC-Check through it and motherboard, ram and processor all passed. I
    > can't see any blown caps either. I really don't like to give it back as
    > repaired!!! But maybe I will have to with a warning.


    I'm sure you've tried this, but, just in case you haven't, what happens if
    you power it up, let it sit for a few minutes, and then press reset or
    short the reset pins?

    > Lizzieb
    > "Jeremy" <> wrote in message
    > news:iQhNf.51739$%...
    >> Check the motherboard for blown caps. If any are present replace
    >> motherboard. If not, remove the motherboard from the case, place it on
    >> something non-conductive, and power it on with just the power supply,
    >> processor, and RAM. You can use a pen or other small metal object to
    >> turn
    >> it on by shorting the power header. If the system power on, run
    >> memtest86 overnight just to be sure, the RAM is probably not your problem
    >> but it never hurts to be sure.
    >>
    >> This is not the behavior of a properly working motherboard. I would
    >> suspect strongly that the board is bad or something in the case is
    >> causing
    >> a short. Are there any components that you forgot to hook up when you
    >> used the 100W?
    >>
    >> Selling the customer the 100W PS may seem like an easy out but it is not
    >> really a good fix.
    >>
    >> Thanks,
    >>
    >> Jeremy
    >>
    >> lizzieb wrote:
    >>> Hi
    >>>
    >>> I got a PC in to repair and all that was happening was the fans were
    >>> coming
    >>> on and nothing else. It is a Packard Bell Imedia celeron 1.3ghz. So I
    >>> thought I would try changing the power supply. It had a 215watt supply
    >>> so tried it with a new 400watt PSU. Still just the fans
    >>> coming on. So just in case the new PSU was duff I tried it with an old
    >>> 100w PSU from an old Time machine and it worked perfectly! Tried it with
    >>> a couple of other PSUs and none worked - only this old 100watt one!
    >>>
    >>> What am I do do? Puzzled too.
    >>>
    >>> Lizzieb
    >>>
    >>>


    --
    --John
    to email, dial "usenet" and validate
    (was jclarke at eye bee em dot net)
     
    J. Clarke, Mar 1, 2006
    #4
  5. lizzieb

    lizzieb Guest

    Wow it worked! What does this mean? There is no reset switch on the PC
    case.

    Lizzieb

    "J. Clarke" <> wrote in message
    news:...
    > lizzieb wrote:
    >
    >> I have just done what you suggested but the situation is just the same. I
    >> ran PC-Check through it and motherboard, ram and processor all passed. I
    >> can't see any blown caps either. I really don't like to give it back as
    >> repaired!!! But maybe I will have to with a warning.

    >
    > I'm sure you've tried this, but, just in case you haven't, what happens if
    > you power it up, let it sit for a few minutes, and then press reset or
    > short the reset pins?
    >
     
    lizzieb, Mar 1, 2006
    #5
  6. lizzieb

    J. Clarke Guest

    lizzieb wrote:

    > Wow it worked! What does this mean? There is no reset switch on the PC
    > case.


    This is the classic symptom of a "Power good" problem.

    Pin 8 on the ATX power supply connector is called "PWR_OK" and serves the
    same function at "Power Good" on the earlier AT power supplies. It is
    supposed to go high once the power supply voltages have stabilized and the
    motherboard isn't supposed to initiate the boot process until PWR_OK goes
    high.

    Some motherboard designers, for reasons known only to themselves put their
    own PWR_OK timer on their boards which causes the board to initiate the
    boot process on its schedule and not the power supply's schedule. If the
    power supply voltages come stable fast enough then it's not a problem, if
    they don't then the board doesn't boot. Sometimes the values of the
    components in the timer circuit drift and shorten the delay provided by the
    onboard timer, which sounds like it may be what happened in this case.

    If you've got the docs for the motherboard or if the jumpers are well
    marked, see if you can find a jumper that lets the board use the power
    supply's PWR_OK signal instead of the onboard signal--sometimes there is
    one. If not then you're going to have to swap power supplies until you
    find one that provides sufficient wattage to drive the board and stabilizes
    its voltages fast enough to make the board happy. Trouble is if the timer
    continues to drift eventually the machine will be unable to boot from the
    new power supply.

    A workaround is to wire a relay to the power-good pin such that the board is
    held in reset until power good becomes active. That doesn't always work
    though and I'd talk to the owner about it before I did it.

    Once I reverse engineered a board to the point that I could increase the
    timer delay, however I realized later that unless you're a starving student
    in desperate need of a working machine or just want to do it for jollies
    that is not a productive use of time--if I was being paid any kind of
    reasonable wage I could have gotten a new machine for the hours I put into
    fixing that one.

    > Lizzieb
    >
    > "J. Clarke" <> wrote in message
    > news:...
    >> lizzieb wrote:
    >>
    >>> I have just done what you suggested but the situation is just the same.
    >>> I ran PC-Check through it and motherboard, ram and processor all passed.
    >>> I can't see any blown caps either. I really don't like to give it back
    >>> as repaired!!! But maybe I will have to with a warning.

    >>
    >> I'm sure you've tried this, but, just in case you haven't, what happens
    >> if you power it up, let it sit for a few minutes, and then press reset or
    >> short the reset pins?
    >>


    --
    --John
    to email, dial "usenet" and validate
    (was jclarke at eye bee em dot net)
     
    J. Clarke, Mar 1, 2006
    #6
  7. lizzieb

    lizzieb Guest

    Many many thanks. It is so great to get these problems solved and feel I
    can tell my customer with some authority what is wrong with her computer.
    She did say she was planning to get a new one soon.

    Lizzieb

    "J. Clarke" <> wrote in message
    news:...
    > lizzieb wrote:
    >
    >> Wow it worked! What does this mean? There is no reset switch on the PC
    >> case.

    >
    > This is the classic symptom of a "Power good" problem.
    >
    > Pin 8 on the ATX power supply connector is called "PWR_OK" and serves the
    > same function at "Power Good" on the earlier AT power supplies. It is
    > supposed to go high once the power supply voltages have stabilized and the
    > motherboard isn't supposed to initiate the boot process until PWR_OK goes
    > high.
    >
    > Some motherboard designers, for reasons known only to themselves put their
    > own PWR_OK timer on their boards which causes the board to initiate the
    > boot process on its schedule and not the power supply's schedule. If the
    > power supply voltages come stable fast enough then it's not a problem, if
    > they don't then the board doesn't boot. Sometimes the values of the
    > components in the timer circuit drift and shorten the delay provided by
    > the
    > onboard timer, which sounds like it may be what happened in this case.
    >
    > If you've got the docs for the motherboard or if the jumpers are well
    > marked, see if you can find a jumper that lets the board use the power
    > supply's PWR_OK signal instead of the onboard signal--sometimes there is
    > one. If not then you're going to have to swap power supplies until you
    > find one that provides sufficient wattage to drive the board and
    > stabilizes
    > its voltages fast enough to make the board happy. Trouble is if the timer
    > continues to drift eventually the machine will be unable to boot from the
    > new power supply.
    >
    > A workaround is to wire a relay to the power-good pin such that the board
    > is
    > held in reset until power good becomes active. That doesn't always work
    > though and I'd talk to the owner about it before I did it.
    >
    > Once I reverse engineered a board to the point that I could increase the
    > timer delay, however I realized later that unless you're a starving
    > student
    > in desperate need of a working machine or just want to do it for jollies
    > that is not a productive use of time--if I was being paid any kind of
    > reasonable wage I could have gotten a new machine for the hours I put into
    > fixing that one.
    >
    >> Lizzieb
    >>
    >> "J. Clarke" <> wrote in message
    >> news:...
    >>> lizzieb wrote:
    >>>
    >>>> I have just done what you suggested but the situation is just the same.
    >>>> I ran PC-Check through it and motherboard, ram and processor all
    >>>> passed.
    >>>> I can't see any blown caps either. I really don't like to give it back
    >>>> as repaired!!! But maybe I will have to with a warning.
    >>>
    >>> I'm sure you've tried this, but, just in case you haven't, what happens
    >>> if you power it up, let it sit for a few minutes, and then press reset
    >>> or
    >>> short the reset pins?
    >>>

    >
    > --
    > --John
    > to email, dial "usenet" and validate
    > (was jclarke at eye bee em dot net)
     
    lizzieb, Mar 1, 2006
    #7
  8. lizzieb wrote:
    > I have just done what you suggested but the situation is just the same. I
    > ran PC-Check through it and motherboard, ram and processor all passed. I
    > can't see any blown caps either. I really don't like to give it back as
    > repaired!!! But maybe I will have to with a warning.
    >
    > Lizzieb

    I apologize for jumping in here. From all that was said below, I am
    wondering, if, the connector on the motherboard, for the PSU is defective.

    I am saying this because of no caps being blown and, the original PSU
    being 215w yet, only the 100w PSU gets it powered up.

    Christopher


    > "Jeremy" <> wrote in message
    > news:iQhNf.51739$%...
    >
    >>Check the motherboard for blown caps. If any are present replace
    >>motherboard. If not, remove the motherboard from the case, place it on
    >>something non-conductive, and power it on with just the power supply,
    >>processor, and RAM. You can use a pen or other small metal object to turn
    >>it on by shorting the power header. If the system power on, run memtest86
    >>overnight just to be sure, the RAM is probably not your problem but it
    >>never hurts to be sure.
    >>
    >>This is not the behavior of a properly working motherboard. I would
    >>suspect strongly that the board is bad or something in the case is causing
    >>a short. Are there any components that you forgot to hook up when you
    >>used the 100W?
    >>
    >>Selling the customer the 100W PS may seem like an easy out but it is not
    >>really a good fix.
    >>
    >>Thanks,
    >>
    >>Jeremy
    >>
    >>lizzieb wrote:
    >>
    >>>Hi
    >>>
    >>>I got a PC in to repair and all that was happening was the fans were
    >>>coming
    >>>on and nothing else. It is a Packard Bell Imedia celeron 1.3ghz. So I
    >>>thought I would try changing the power supply. It had a 215watt supply so
    >>>tried it with a new 400watt PSU. Still just the fans
    >>>coming on. So just in case the new PSU was duff I tried it with an old
    >>>100w PSU from an old Time machine and it worked perfectly! Tried it with
    >>>a couple of other PSUs and none worked - only this old 100watt one!
    >>>
    >>>What am I do do? Puzzled too.
    >>>
    >>>Lizzieb
    >>>
    >>>

    >
    >
     
    Christopher Range, Mar 2, 2006
    #8
  9. lizzieb

    lizzieb Guest

    Hi

    If your theory is correct - what could I do to check it out?

    Lizzieb

    "Christopher Range" <> wrote in message
    news:k9wNf.2745$...
    > lizzieb wrote:
    >> I have just done what you suggested but the situation is just the same. I
    >> ran PC-Check through it and motherboard, ram and processor all passed. I
    >> can't see any blown caps either. I really don't like to give it back as
    >> repaired!!! But maybe I will have to with a warning.
    >>
    >> Lizzieb

    > I apologize for jumping in here. From all that was said below, I am
    > wondering, if, the connector on the motherboard, for the PSU is defective.
    >
    > I am saying this because of no caps being blown and, the original PSU
    > being 215w yet, only the 100w PSU gets it powered up.
    >
    > Christopher
    >
    >
    >> "Jeremy" <> wrote in message
    >> news:iQhNf.51739$%...
    >>
    >>>Check the motherboard for blown caps. If any are present replace
    >>>motherboard. If not, remove the motherboard from the case, place it on
    >>>something non-conductive, and power it on with just the power supply,
    >>>processor, and RAM. You can use a pen or other small metal object to
    >>>turn it on by shorting the power header. If the system power on, run
    >>>memtest86 overnight just to be sure, the RAM is probably not your problem
    >>>but it never hurts to be sure.
    >>>
    >>>This is not the behavior of a properly working motherboard. I would
    >>>suspect strongly that the board is bad or something in the case is
    >>>causing a short. Are there any components that you forgot to hook up
    >>>when you used the 100W?
    >>>
    >>>Selling the customer the 100W PS may seem like an easy out but it is not
    >>>really a good fix.
    >>>
    >>>Thanks,
    >>>
    >>>Jeremy
    >>>
    >>>lizzieb wrote:
    >>>
    >>>>Hi
    >>>>
    >>>>I got a PC in to repair and all that was happening was the fans were
    >>>>coming
    >>>>on and nothing else. It is a Packard Bell Imedia celeron 1.3ghz. So I
    >>>>thought I would try changing the power supply. It had a 215watt supply
    >>>>so tried it with a new 400watt PSU. Still just the fans
    >>>>coming on. So just in case the new PSU was duff I tried it with an old
    >>>>100w PSU from an old Time machine and it worked perfectly! Tried it with
    >>>>a couple of other PSUs and none worked - only this old 100watt one!
    >>>>
    >>>>What am I do do? Puzzled too.
    >>>>
    >>>>Lizzieb
    >>>>
    >>>>

    >>
     
    lizzieb, Mar 2, 2006
    #9
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Silverstrand

    Modular Power Supplies @ A True Review

    Silverstrand, Jun 28, 2005, in forum: Front Page News
    Replies:
    2
    Views:
    762
    unholy
    Jun 29, 2005
  2. Silverstrand

    HEC Power Supplies @ ThinkComputers.org

    Silverstrand, Jul 17, 2005, in forum: Front Page News
    Replies:
    2
    Views:
    804
    zachig
    Jul 20, 2005
  3. =?Utf-8?B?SlA=?=

    Power supplies

    =?Utf-8?B?SlA=?=, Nov 9, 2003, in forum: Microsoft Certification
    Replies:
    4
    Views:
    511
    Larry Samuels MS-MVP XP \(Shell/User\)
    Nov 15, 2003
  4. Jeff
    Replies:
    1
    Views:
    539
    Chris Thomas
    Apr 26, 2004
  5. Replies:
    0
    Views:
    361
Loading...

Share This Page