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ATX Computer Power Supply Wiring Question

Discussion in 'Electronic Basics' started by Searcher7, Dec 15, 2007.

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  1. Searcher7

    Searcher7 Guest

    I am putting an ATX computer power supply into an arcade video game
    cabinet, and I want to make sure that all of the cabinet's harness'
    power/ground pins are used. The harness has four pins designated for
    +12V, but the power supply's main 20-pin output connector has only one
    +12V pin.

    So I intend to use the two +12V pins from the square 4-pin output, and
    one more +12V pin from one of the 4-pin peripheral power connectors.

    Do I need to use the grounds on these same connectors also?

    I already have enough(eight) grounds on the main 20-pin connector(if I
    include the 3.3V sense), but I wanted to be sure.

    Any advice would be appreciated.

    Thanks a lot.

    Darren Harris
    Staten Island, New York.
     
  2. Baron

    Baron Guest

    All the grounds are common as are the +12 volts. Its your choice ! But
    I would use all the wires if possible. That way you get less volts
    drop.
     
  3. None of those +12v lines are separate. They all come from the same
    point in the power supply, and the multiple lines are there either for
    better current capacity (it's sometimes easier to have a number of smaller
    wires in parallel than one big bulky wire that is too stiff to do much
    with), or to bring power to different places (as in the case of the power
    connectors for the drives.

    It really depends on the current you demand from the power supply. The
    more current the game uses, the more there will be a need for multiple
    wires so the voltage drop across them is not problematic.

    The ground wires are the same thing, if what you are using can't handle
    the current needs of the game, then there will be voltage drop.

    But in the case of the ground lines, the issue isn't just the +12v lines,
    but the +5v lines too, since the ground lines are common to both supplies.


    Michael
     
  4. Searcher7

    Searcher7 Guest

    Thanks Micheal and Baron.

    The Game's harness has two power connectors. One with four +12V pins
    and four Grounds. The other with two +3.3V, four +5V, and four Grounds.
    (Then of course there is the Hot, Neutral, and ground input
    connector).

    I'll make sure all of these power pins and grounds are being used.
    (With all the output leads/connectors the power supply has this of
    course will not be a problem).

    Since this is an ATX power supply I will have to connect one "power
    on" pin to one of the grounds.
    I assume that the +3.3V sense can be treated like any of the other
    grounds. And the only two pins I won't bother with are the "Power
    Good" and +5V Standby", whatever that is.

    Thanks a lot.

    Darren Harris
    Staten Island, New York.
     
  5. Sparkfish1

    Sparkfish1 Guest

    As most have said all the ground ( black) wires are common and go back
    to one point
    To minimise the voltage drop and ensure the current carrying capacity
    it is best to use all the ground wires

    I have made some bench power supplies from salvaged Computer PSU and
    found this source informative, instructive and useful
    http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply

    I found searching other "conversion" articles a useful way of
    understanding the wiring

    I hope this helps
     
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