Is A 110v PSU Ok On 240v

Discussion in 'NZ Computing' started by Pickles, Jun 26, 2005.

  1. Pickles

    Pickles Guest

    I had told a friend who had two 110v psu's that he could
    use them either directly on 240v in NZ or with them both
    connected in series to the 240v NZ mains. He stated
    that they were good quality psu's and I believed 240v
    shouldn't be a problem, but two connected in series to
    the 240v mains would be less likely to blow the caps etc.

    Some other expert friend of my friend told him he'd need
    to buy 240v psu's because the 110v ones won't handle
    240v. Before I take the bull by it's horns and try one of
    these 110v psu's on 240v, could some expert here tell
    me if I'm correct or am I making a big mistake?

    Pickles, Jun 26, 2005
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  2. *DON'T DO IT!* Doing so would be stupid - Stupid - STUPID - *STUPID*
    You are risking your life and safety, and may possibly cause a fire. And
    that's just the start.
    Nicolaas Hawkins, Jun 26, 2005
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  3. Pickles

    Daver Guest

    You can't use then in series as for a start you can't guarrantee they will
    be handling the same load. Any difference in load is going to result in one
    or other getting more than half. If they are 110v supplies then its also
    unlikely they will survive 230v unless stated. Unlike power supplies
    intended for the international market which may handle 230 down to 110 ones
    that originate in the US tend to be dedicated to 110.
    Daver, Jun 26, 2005
  4. Pickles

    Pickles Guest

    Why???? Please explain Nicolaas.
    Pickles, Jun 26, 2005
  5. Pickles

    Pickles Guest

    But there should be similar impedance into either psu if they are the same
    make/model and if the components such as capacitors are at least the
    specified rating, one on it's own, or both in series should work ok.

    Pickles, Jun 26, 2005
  6. Pickles

    Murray Symon Guest

    If the PSU has been designed specifically for 110V, then the components
    will have been selected with maximum ratings that give a safety margin
    according to the rated input.

    The designer will never have intended that input limit to be exceeded.
    If he did, then the PSU would be rated for 110/220/230V or for a maximum
    of 230V.

    Also, by ignoring the voltage limit, you may be invalidating your
    Murray Symon, Jun 26, 2005
  7. Pickles

    Pickles Guest

    Hello Murray, *smile*
    I doubt whether a blown 240v fuse on the household fuse board
    would have much impact on anyones insurance policy, and I'm sure
    most atx psu's these days are built using components that will handle
    well in excess of their rated voltage. (Unless the psu in question is of
    poor quality and low cost)

    Pickles, Jun 26, 2005
  8. Pickles

    Murray Symon Guest

    No, they're built to minimise cost - so the cheapest, lowest-spec parts
    that will meet the design specificiations will be used.
    Also, you cannot consider all PSU's as being designed and/or built the
    same. What you may get away with for one model may cause another to
    fail catastrophically.

    As Nicolaas has pointed out, you shouldn't be considering such things.

    That is, unless you are a qualified engineer with experience in such
    circuits - but then you wouldn't have had to ask the question in the
    first place, would you?
    Murray Symon, Jun 26, 2005
  9. Pickles

    Pickles Guest

    You are onto my game Murray.....heh
    But it's good fun to get the reactions of certain know it all fools
    on a cold Sunday morning.

    Pickles, Jun 26, 2005
  10. Pickles

    Pickles Guest

    Good question Bret.
    What's the answer Chris? heh heh

    Pickles, Jun 26, 2005
  11. No. And I'm getting the impression you are simply trolling.


    .... One often gets much more than one asks for - not all of it necessarily
    Nicolaas Hawkins, Jun 26, 2005
  12. Keeping it simple, for the same sorts of reasons that you wouldn't plug
    your car's 12-volt stereo straight into a bloody great 24-volt Kenworth
    truck. Simply isn't designed to withstand the extra voltage.
    I'll leave others to fill you in with more detailed information once they
    are satisfied you aren't just trolling. I'm not.
    Nicolaas Hawkins, Jun 26, 2005
  13. At the risk of being accused of talking to myself:

    Nicolaas Hawkins, Jun 26, 2005
  14. Pickles

    Pickles Guest

    I have the impression you simply don't know what you are
    talking about laddy.

    Pickles, Jun 26, 2005
  15. Pickles

    BTMO Guest

    The most likely thing that will happen is that you will simply burn out the
    primary of the transformer in the power supply, and nothing will happen
    after that. They will simply stop working.

    You *shouldn't* get a fire, and I would be surprised if you blow the house
    fuses (yes, I have read through the thread).

    However, it is a *really* bad idea to try this, because as others have
    pointed out, consumer electronics are made to a price, not a standard. What
    you have in your hands are the two cheapest power supplies (regardless of
    what they cost) that could be made to meet the need they were designed for.
    They *might* catch fire - they will certainly get hot - however, if the
    windings in the transformer get hot enough quickly enough, the wire will
    simply burn through. End of problems.

    If they don't get hot enough quickly enough, the plastic surrounding the
    wire may indeed get hot enough to burn - then you have a problem.
    Potentially a very dangerous one.

    Don't do it.

    Spend the 20 bucks or whatever these things cost now from DSE to get a power
    supply that runs on 240.
    BTMO, Jun 26, 2005
  16. Pickles

    ~misfit~ Guest

    Yeah. I was a bit late on spotting that one. Sorry.
    ~misfit~, Jun 26, 2005
  17. Pickles

    Pickles Guest

    mains input transformers, the 240v goes virtually straight into the
    rectifier which
    turns the ac into a unidirectional current which is then chopped into square
    at the required voltage/s. You can look at the circuit diagram

    Pickles, Jun 26, 2005
  18. Pickles

    BTMO Guest

    Ummm... it has a 240v (well, 230) / 115v switch...

    Just above the bridge rectifier on the diagram.

    My advice is to flick the switch to the appropriate position, and use it as
    BTMO, Jun 26, 2005
  19. Pickles

    ~misfit~ Guest

    LOL!!! The mental midget finally gets called for what he is and proves it by
    trying to pass it off on someone who has him sussed. Stick to playing rugby
    Pickles. Just do what the coach tells you. If you have size 14 boots you
    obviously aren't in the team for your intelligence. Gorillas are big too you
    ~misfit~, Jun 26, 2005
  20. Pickles

    Pickles Guest

    already done that yourself, with a begged or borrowed used psu with
    frayed wires not unlike your nerve endings you say you take the medication

    Old is in your mind. You noticed I'm older than my years. That's what
    and experience does for a young fellow like me. Thankyou for the compliment.

    Pickles, Jun 26, 2005
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