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12vdc power supply problem

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  • 30-07-2012 11:24pm
    #1
    scudster
    Registered Users Posts: 416 ✭✭


    As mentioned above I have a mains run 12VDC power supply which has failed. Its putting out 12v on both terminals and this is the second time its happened. I got the first one replaced under warranty. After they sent the new one I pulled the old one apart and found that one of its capacators had leaked/melted internally.
    The psu is rated at 5amps so it should be capable of running the bunch of LEDs I installed in my parents kitchen. The total draw from the LEDs is about 3.6amps.
    My question is what could cause this to happen?
    Poor wiring on my behalf maybe?


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    #2
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    A short circuit could cause this or it may have over heated. Is there sufficient space around it for cooling? Does it feel hot when powered up and under load ? It may be poor quality.


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    #3
    DublinDilbert
    Registered Users Posts: 5,379 ✭✭✭DublinDilbert


    scudster wrote: »
    As mentioned above I have a mains run 12VDC power supply which has failed. Its putting out 12v on both terminals and this is the second time its happened. I got the first one replaced under warranty. After they sent the new one I pulled the old one apart and found that one of its capacators had leaked/melted internally.
    The psu is rated at 5amps so it should be capable of running the bunch of LEDs I installed in my parents kitchen. The total draw from the LEDs is about 3.6amps.
    My question is what could cause this to happen?
    Poor wiring on my behalf maybe?

    Ummmm how is it putting 12V out on both its terminals? what are you measuring with respect to?

    Do you have a link to the PSU and a link to the LEDs.

    Usually when a cap goes like that, it's cause they used cheap electrolyitic caps in manufacturing. Obviously it won't help if the power supply is running hot and not getting enough cooling.


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    #4
    scudster
    Registered Users Posts: 416 ✭✭scudster


    http://www.oznium.com/ac-adapter

    Its the 5amp one if you look in the photos tab.
    With regards cooling that should not be a problem as its sitting on top of kitchen cabinets with nothing above or around it.
    I'm running 15 x 20" and 4 x 9" tri-chip tubes (warm white). http://www.oznium.com/tri-chip-led-tube

    From their tech info page I calculated that they would pull about 3.6 amps which should be well within its capability.
    There is a junction box splitting these tubes into 3 unequal groups with inline switches. The only possible place for a short to occur would be in the switch box. But even if there was a short the lights shouldnt work at all but they lasted about 4 or 5 months.

    As for it putting out 12v on both terminals I'm not sure how this could happen.


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    #5
    ZENER
    Registered Users Posts: 6,163 ✭✭✭ZENER


    They look fairly cheap tbh. I'd wonder how long they are designed to supply that amount of current for. Pulling over 3.8 Amps from it for a few hours would cause it to heat up drying out any electrolytics inside. Probably using cheap 85 degree caps rather than better quality 105 degree ones.

    Ken


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    #6
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    scudster wrote: »

    As for it putting out 12v on both terminals I'm not sure how this could happen.

    As dublin dilbert said, what do you mean by this?

    You have 2 terminals, and should have 12v between the 2. How do you mean you are getting 12v on both terminals? That sounds like you are measuring between each terminal and a third point??


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    #7
    ZENER
    Registered Users Posts: 6,163 ✭✭✭ZENER


    No offense intended towards the OP but he may not be as technically minded as those of us in the trade, he may simply mean there's 12V on the two wires when he connects a meter to them ?

    Ken


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    #8
    DublinDilbert
    Registered Users Posts: 5,379 ✭✭✭DublinDilbert


    People are only trying to assist. If it is putting out 12v on its output terminals, then it hasn't failed, the issue may ly else where...


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    #9
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    ZENER wrote: »
    No offense intended towards the OP but he may not be as technically minded as those of us in the trade, he may simply mean there's 12V on the two wires when he connects a meter to them ?

    Ken

    Posters need to ask some questions though, in order to assist.

    Maybe they meant there is 12v on the output, and so is asking why it wont work if the 12v is there. Its possibly showing 12v on a multimeter which applies no load to the power supply, but is unable to power the load applied due to failure of the power supply circuitry.


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