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  1. #1
    CrazyJarhead
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    Need some LED help!

    I need some of everyone's expert help out there..! I have been building my LED bike light, it seems forever. Here are the stats:

    2 - 20 mm Triple CREE XP-G R5 boards in series
    1 Luxor - Endor Star Triple board
    2 - 1000mA 3023 Buckpucks

    14.4v 5500 MaH battery pack.

    I am using the CopperHead design that I have found on a number of sites.

    I have the two CREE boards wired in paralell and the Endor star wired on it's own buck. The problem I am having is that I have full power to the Cree board closest to the buck and only 9.6v to the one farthest away (2").

    Can anyone give me some input as to how to remedy my situation? I am getting to the point of chucking everything......However, the wife wouldn't be happy with that.

    Any help or advice is greatly appreciated

  2. #2
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    some pictures of your setup would be most helpfull .

    are the triples them selves series or paralell and in series with each other

    the more info the better the helpfull solutions

  3. #3
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    Quote Originally Posted by CrazyJarhead
    2 - 20 mm Triple CREE XP-G R5 boards in series

    I have the two CREE boards wired in paralell and the Endor star wired on it's own buck. The problem I am having is that I have full power to the Cree board closest to the buck and only 9.6v to the one farthest away (2").
    9.6V is the Vf for a triple XP-G in series. That's what your buckpuck is outputting while holding the current at 1000mA. Describe the symptoms displayed by the second triple and show a wiring diagram and some pictures if possible.

    If the second triple is not lighting at all and the first one is bright, here are some possibilities...
    an open LED in the second triple.
    second triple was wired backward.
    second triple has a mis-mounted LED in the string.

  4. #4
    fuggansonofahowa
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    Quote Originally Posted by Vancbiker
    9.6V is the Vf for a triple XP-G in series. That's what your buckpuck is outputting while holding the current at 1000mA. Describe the symptoms displayed by the second triple and show a wiring diagram and some pictures if possible.

    If the second triple is not lighting at all and the first one is bright, here are some possibilities...
    an open LED in the second triple.
    second triple was wired backward.
    second triple has a mis-mounted LED in the string.
    I concur....check your +'s & -'s....many times this ends in a self-imposed slap to the forehead (at least in my case).

  5. #5
    CrazyJarhead
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    Led Advice

    Gentleman I appreciate your response.

    Both PCB's are suppose to be wired in Series and then I originally had them wired in series as well. However after conversing with Troutie previously I found out that I was not getting enough power from the Buckpuck to run both of them this way and that I would have to wire them in paralell . So after re wiring them in paralell I was getting one to light at full brightness and the other only two of the led's light up and then one not at all. The second one is dim enough you can look directly at it. I've included a couple of pics. This is my first attempt at a light with mostly hand-tools....bare with me.

    As you can see in the picture I am using the CopperHead Design (Troutie has one on his homepage too).

    Wiring is straight fowward....following the outputs on the Buckpuck, except I added an on/off switch to the power wire.

    Any magical words of advice?? Also what would be the best way to tell if all of the LED are in the correct +/- orientation?
    Attached Thumbnails Attached Thumbnails Need some LED help!-100_1335.2.jpg  


  6. #6
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    From your picture the LEDs look like they are on the PCB the right way round but you can make sure as the XP-G has a small dot in the corner for the +
    Attached Thumbnails Attached Thumbnails Need some LED help!-xpg.png  


  7. #7
    fuggansonofahowa
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    Are you measuring +9.6V on both the good and bad one?

  8. #8
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    Can you post a pic of the connections from the buck puck to the stars? I am curious since the one on the left has a yellow line going to it (which would normally be blue IIRC). I think yellow on the Buckpuck is normally ref or ctrl which would only be 5v. Normally a 5k ohm linear taper pot would be placed over the ctrl and ref lines to control the brightness. Is the yellow line to the star on the left an added jumper or does it go directly into the buckpuck?

    Are you running each star to one buck and then have the bucks paralleled with the battery or are the stars in parallel on the output of one buckpuck?

    Here is the datasheet for the buckpuck:
    http://www.luxdrive.com/download.php...3-BuckPuck.pdf

    I'd suggest connecting one buckpuck to one star at a time per the datasheet and test the output. Simplest would be to just connect the Vin +/ and - from the battery, and the LED+ and - to one star at a time, then test (you could connect a pot to the ctrl and ref lines if it is already and you want to test those too). See figure 3 in the diagram on the datasheet for the simplest method of hookup to test.

  9. #9
    CrazyJarhead
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    Thanks for the sharp eye Huffy, the two wires on the left one are wired correctly. The yellow and white wire are from an old computer I tore apart....waste not want not.

    I wired both buckpucks up seperately to the triple's and I get one to light and the other not at all (one puck is only putting out 3v....the new one). I then wired each triple seperately and they lit.....however the one with the none lighting led was dimmer. Could that be the resistance causing it to not light all the way?

    The setup is the same as the one Troutie just posted....except for the driver. Is there something I'm missing?

  10. #10
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    Cool, just making sure about the yellow line

    So this is how I am understanding this (calling the triple stars A and B):

    New Buckpuck = 3v out with the 14.4V battery and connected to Triple A - No light
    Old Buckpuck + Triple B = OK
    Old Buckpuck + Triple A = Lights, but LEDs dimmer

    Does this sound correct?

  11. #11
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    I can't be sure from the picture, but it almost looks like you did some cutting or grinding on the MCPCBs to make them fit into the copper housings? If so, it's possible you caused some shorting between the PCB traces and the metal core of the MCPCBs. The insulation layer between the traces and the metal core is extremely thin.

    If this is what's happened, you may be able to fix it if you clean up all the edges of the MCPCB with something like a high speed Dremel tool with a fine grinding stone. Only grind parallel to the plane of the MCPCB. If grind perpendicular, you'll cause shorts because the grinding action will pull tiny burrs across the thin insulation layer into contact with the metal core.

  12. #12
    CrazyJarhead
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    Quote Originally Posted by HuffyPuffy
    Cool, just making sure about the yellow line

    So this is how I am understanding this (calling the triple stars A and B):

    New Buckpuck = 3v out with the 14.4V battery and connected to Triple A - No light
    Old Buckpuck + Triple B = OK
    Old Buckpuck + Triple A = Lights, but LEDs dimmer

    Does this sound correct?

    That is correct. The new buck is basically no good. Old buckPuck + Triple B and A you have 16 v at A and only 9.6v at B.

  13. #13
    CrazyJarhead
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    Quote Originally Posted by MtbMacgyver
    I can't be sure from the picture, but it almost looks like you did some cutting or grinding on the MCPCBs to make them fit into the copper housings? If so, it's possible you caused some shorting between the PCB traces and the metal core of the MCPCBs. The insulation layer between the traces and the metal core is extremely thin.

    If this is what's happened, you may be able to fix it if you clean up all the edges of the MCPCB with something like a high speed Dremel tool with a fine grinding stone. Only grind parallel to the plane of the MCPCB. If grind perpendicular, you'll cause shorts because the grinding action will pull tiny burrs across the thin insulation layer into contact with the metal core.
    First off......Gorgeous light work. I looked at your light history page. Very nice.

    The silver mark you see on the upper right of the triple is actually Arctic SIlver, the triples actually have about 2 mm all the way around them inside the copper cap.

  14. #14
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    Quote Originally Posted by CrazyJarhead
    That is correct. The new buck is basically no good. Old buckPuck + Triple B and A you have 16 v at A and only 9.6v at B.
    That sux, it sounds like you could have a messed up board too then. When you measured these, they were tested with the old buckpuck and one star at at time connected, right? Is "Triple A" totally dead now or do you still get something out of it?

  15. #15
    CrazyJarhead
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    Quote Originally Posted by HuffyPuffy
    That sux, it sounds like you could have a messed up board too then. When you measured these, they were tested with the old buckpuck and one star at at time connected, right? Is "Triple A" totally dead now or do you still get something out of it?
    Yes, I tested them individually with the old one and they were fine. Triple A was still not as bright as Triple B. Triple is not completely dead. I get the bottom two LED's to light, they're bright but not so bright you can't look directly at them.....with no spots in the eyes.

  16. #16
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    Sorry to hear that, not that getting spots in your eyes is a good thing usually

    I am about out of easy ideas, but I think I'd clean off all the arctic silver, esp around the edges just in case. I read that although it is not really very conductive, it is slightly capacitive - just best to get rid of anything that could be a problem to test.

    Then if it is still a problem you could try cleaning up the solder contacts a bit to make sure there is nothing close to bridging anything. Some flux may help with this to get the solder flowing again.

    I'd test the star outside the enclosure, just sink it to a flat bit of aluminum or copper, with a small dab of thermal compound on the back of the star, not enough to seriously ooze out. Aside from that it sounds like a new star may be needed - I hope if anyone has other ideas they will post them up though, cause I'd hate for you to give up based on my advice, if there is hope to save it.

    Other more difficult options would be to test each LED in the board individually but that would be a big PITA and and could damage the board or LED's depending on how it is done. The suspected bad LED could also be bypassed, but then it would be a 2 LED star and that would probably not be so great. If you need to salvage the board or LED's and have a spare XP-G, the boards can be reflowed but it is tricky. There was a thread where Troutie did that with a heat gun sometime ago. I have used a jet lighter in the past with XR-E without a problem (just to remove LED's not replace) but I think for these I'd use a hotplate if I were gonna attempt a repair by replacing one of the LED's.

  17. #17
    CrazyJarhead
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    I think I am going to rebuild the whole thing.....much to my wife's dismay....Except this time I am going to run a buckpuck for each triple..

  18. #18
    CrazyJarhead
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    Oh and order a new triple to replace the one that only has two lighting up

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