Hi I have installed a small run of LEDs but they do not work at all unless I reverse the connection that goes directly on to the stip so that it's not lining up with 12v symbol. I tested everything before cutting the strip to length and it worked fine but now it will not switch on with remote. I have changed the controller and remote with different ones but still no go. I would be very greatful for any help. Thanks

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    Hello, and welcome to Stack Exchange. A manufacturer/model number might help, as would a picture or two. – Daniel Griscom Feb 11 '16 at 1:37
  • I'm confused, you can get it to work if you swap the wires? If so, that is the correct orientation, and possibly your supply or the markings are incorrect. LEDs will only work one way, and if they're working at all, that's the way they need to be. If you have a test meter, check the polarity at the strip and the supply. – DaveM May 18 '18 at 2:12

I just received some LED tape from a supplier in the US from ebay. The polarity marked on the tape was incorrect and the factory ends had the red wire to the negative mark. The markings on your strips may also be incorrect.


Look very closely on the cut LED strips and make sure you did not short the + and - sides to each other somewhere, such as where you cut it... if the strip is shorted, the power supply will sense that and shut it down.

Also keep in mind, polarity matters on LEDs - if you hook the wires to the strip backwards, it will refuse to light. Won't do it any damage, just reverse polarity and it should light.

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    An LED hooked up backwards can let the magic smoke out if the supply curent is avaiable, many of the strings do not have reverse polarity protection. – Ed Beal Feb 11 '16 at 14:55

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