computer power supply

Discussion in 'The Projects Forum' started by hobbyist, Nov 6, 2008.

  1. hobbyist

    Thread Starter Distinguished Member

    Aug 10, 2008
    764
    56
    Hi,
    Does anyone know how I can get a computer power supply to turn on.
    This is the kind with the soft off feature.

    labeling shows:

    +3.3v 24A orange
    +5v 35A Red
    +12v 12A yellow
    +5vSB 2A purple
    -5v 0.5A white
    -12v 0.8A Blue
    PS-ON Green
    P.G Grey

    I'm assuming P.G means Power Ground.
    and PS-on is to turn it on.

    Do I connect the green wire with one of the +volts?

    Thankyou...
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    Connect the green wire to ground. Wikipedia has a pretty decent article on these units.
     
    Last edited: Nov 7, 2008
  3. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    P.G means power good
     
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,680
    900
    Most ATX supplies also require a load on the 5V line to work well. Here is an Instructable on it. The same information can be found in other places too. John
     
  5. hobbyist

    Thread Starter Distinguished Member

    Aug 10, 2008
    764
    56
    Thanks guys
    I will look at those links, you gave me...
     
    Last edited: Nov 7, 2008
  6. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    In the Instructable, the author says he snipped off all but one of the ground wires close to the PCB.

    I don't recommend doing this, as a single wire won't support the current that the supply can put out. I used solder lugs to attach the wires to banana jacks.

    Note that many banana jacks have low amperage ratings. I used a pair of 10A rated jacks for my +5v and +3.3v supplies, as otherwise the voltage drop across them would have been too high when powering heavy loads.
     
  8. hobbyist

    Thread Starter Distinguished Member

    Aug 10, 2008
    764
    56
    Thanks for the excellent advise.

    Thanks for the links Bertus.
     
  9. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    Actually you can reduce the number of ground wires if you are not powering something as complex as a computer.

    The plethora of black wires is not to do with total curent handling, if you think about it there need be no more black wires than rail voltage wires, since they are generally all the same gauge.

    The reason for the extra ground wires is that they are taken to a star grounding point within the psu to prevent the large circulating currents causing small ground potential differences in different parts of the circuitry and upsetting the logic levels etc.
     
Loading...