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Using pc power supply for subwoofer amplifier, almost there NEED HELP

Discussion in 'Power Electronics' started by dereelmatts, Jun 8, 2016.

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  1. dereelmatts

    dereelmatts

    2
    0
    Jun 8, 2016
    I am hooking up a PC power supply to power my 12v speaker amplifier, I hooked all the wires together and managed to get the power supply to turn on and put 12v 30a out but when I hook the positive and ground wire (all the 12v wires so I get all the current) to my amp the power supply ?Short circuits? and turns off. To make it weirder, if I hook it up to my amp through some thin alligator clip wires it works fine, but those wires wont be able to handle the load.

    So why does it work with thin wires but not a full large wire connection?
     
  2. dereelmatts

    dereelmatts

    2
    0
    Jun 8, 2016
    Side note, I think it has something to do with resistance. There are around 10 ground wires, traditionally you are suppose to splice them into one heavy guage wire. If I hook this wire up it doesnt work, but if I hook up a alligator wire from this to the amp it works.
     
  3. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Some power supplies require an additional load on the 5V rail in order to properly regulate the 12V rail. Try sticking a big wattage resistor on there and see what happens.
    The alligator clip vs. using a big gauge wire only makes sense if the current draw is on right on the edge of the PSU safety trigger.
    The thinner wire/alligator clip may introduce just enough resistance to help.. but the amplifier may just compensate by pulling more current if it get's a lower voltage so I can't say for sure.
     
  4. pgib8

    pgib8

    99
    22
    Jul 26, 2015
    can you try to hook up just one of the 12v wires for testing? if that works, then add a second. I think it's OK to have all the black ones together, but I'm not sure if the red ones are supposed to come together. Perhaps these are isolated supplies.
     
  5. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Red typically = 5V rail.

    You bring up a great point though...
    I've known of some PSUs that provide two 12V rails...
    Would be a good idea to bind the black together, and attempt one yellow, then gradually add them on.

    Other option is opening the case, and checking where the yellow wires connect to the board. If they are not internally connected, it could be doing some funny stuff.
     
  6. pgib8

    pgib8

    99
    22
    Jul 26, 2015
    i mixed up red and yellow, but yes you know what i meant. tie all black together and gradually add one positive rail at a time and perhaps also try different combinations.
     
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