Wiring question.

Discussion in 'NZ Computing' started by ~misfit~, Jul 17, 2006.

  1. ~misfit~

    ~misfit~ Guest

    Hi folks,

    I have an old Commodore external power supply that I was about to throw out,
    then realised it could be useful for powering external drives etc. I have a
    wee PSU that terminates in a molex for powering one drive but it gets quite
    warm and doesn't have a switch on it. The Commodore one has a switch (and is
    eight times the size).

    My question:

    The PSU has 5 pins, +12V, -12V, +5V, Shield ground and signal ground. Which
    of the 'grounds' should I use for the -5V when I wire it to a Molex?

    Thanks.
    --
    Shaun.
    ~misfit~, Jul 17, 2006
    #1
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  2. ~misfit~

    PeeCee Guest

    "~misfit~" <> wrote in message
    news:...
    > Hi folks,
    >
    > I have an old Commodore external power supply that I was about to throw
    > out, then realised it could be useful for powering external drives etc. I
    > have a wee PSU that terminates in a molex for powering one drive but it
    > gets quite warm and doesn't have a switch on it. The Commodore one has a
    > switch (and is eight times the size).
    >
    > My question:
    >
    > The PSU has 5 pins, +12V, -12V, +5V, Shield ground and signal ground.
    > Which of the 'grounds' should I use for the -5V when I wire it to a Molex?
    >
    > Thanks.
    > --
    > Shaun.



    Shaun

    **at your risk**

    (assuming -5V means +5V)

    There is likely little difference between them, they should be all tied back
    to the same ground point anyway.

    The size is no guarantee of current capability, the Commodore supply is
    probably hitting 20+ years old and used the technology of the time. If I
    remember right they are 'potted' supplies ie filled with epoxy, supposedly
    for 'reliability' but in practice to make it difficult for a local radio /
    tv tech to repair, meaning Commodore sold 1 new overpriced power supply.
    Heaps of them were tossed simply because the fuse had broken with age.

    Best
    Paul.
    PeeCee, Jul 17, 2006
    #2
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  3. ~misfit~

    ~misfit~ Guest

    PeeCee wrote:
    > "~misfit~" <> wrote in message
    > news:...
    > > Hi folks,
    > >
    > > I have an old Commodore external power supply that I was about to
    > > throw out, then realised it could be useful for powering external
    > > drives etc. I have a wee PSU that terminates in a molex for
    > > powering one drive but it gets quite warm and doesn't have a switch
    > > on it. The Commodore one has a switch (and is eight times the size).
    > >
    > > My question:
    > >
    > > The PSU has 5 pins, +12V, -12V, +5V, Shield ground and signal
    > > ground. Which of the 'grounds' should I use for the -5V when I wire
    > > it to a Molex? Thanks.
    > > --
    > > Shaun.

    >
    >
    > Shaun
    >
    > **at your risk**
    >
    > (assuming -5V means +5V)


    I'm talking about the -5V wire to fix to the black wire on the Molex next to
    the red (+5V) wire.

    > There is likely little difference between them, they should be all
    > tied back to the same ground point anyway.


    Ok, thanks.

    > The size is no guarantee of current capability,


    Hehee, but isn't it all about size?

    I know you're right. I've just checked (claimed) ratings of the two supplies
    and the cigarette-packet sized one claims 2A on the 12V rail and another 2A
    on the 5V. The Commadore one only says 1A on the 12V but 4.3A on the 5V.
    Therefore it's probably no good for my needs anyway.

    > the Commodore supply
    > is probably hitting 20+ years old and used the technology of the
    > time. If I remember right they are 'potted' supplies ie filled with
    > epoxy, supposedly for 'reliability' but in practice to make it
    > difficult for a local radio / tv tech to repair, meaning Commodore
    > sold 1 new overpriced power supply. Heaps of them were tossed simply
    > because the fuse had broken with age.
    > Best
    > Paul.


    Cheers,
    --
    Shaun.
    ~misfit~, Jul 17, 2006
    #3
  4. ~misfit~

    jasen Guest

    On 2006-07-17, ~misfit~ <> wrote:
    > Hi folks,
    >
    > I have an old Commodore external power supply that I was about to throw out,
    > then realised it could be useful for powering external drives etc. I have a
    > wee PSU that terminates in a molex for powering one drive but it gets quite
    > warm and doesn't have a switch on it. The Commodore one has a switch (and is
    > eight times the size).
    > My question:
    >
    > The PSU has 5 pins, +12V, -12V, +5V, Shield ground and signal ground. Which
    > of the 'grounds' should I use for the -5V when I wire it to a Molex?


    use both grounds.

    what do you need -5 for ? IME drives want +5 and +12

    how much power is available on the 12V?

    Bye.
    Jasen
    jasen, Jul 18, 2006
    #4
  5. ~misfit~

    jasen Guest

    On 2006-07-17, ~misfit~ <> wrote:
    > PeeCee wrote:


    >> Shaun
    >>
    >> **at your risk**
    >>
    >> (assuming -5V means +5V)

    >
    > I'm talking about the -5V wire to fix to the black wire on the Molex next to
    > the red (+5V) wire.


    you want 0V (ground) on both black wires.

    > I know you're right. I've just checked (claimed) ratings of the two supplies
    > and the cigarette-packet sized one claims 2A on the 12V rail and another 2A
    > on the 5V. The Commadore one only says 1A on the 12V but 4.3A on the 5V.
    > Therefore it's probably no good for my needs anyway.


    yeah, probably not, unless it's a notepad drive.

    Bye.
    Jasen
    jasen, Jul 18, 2006
    #5
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