Buckpuck gone bad??- Mtbr.com
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  1. #1
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    Buckpuck gone bad??

    I attempted in vain to search for an answer to my question, but I apologize in advance if I missed the obvious.


    I'm having some issues with building a light, and I think the problem is surrounding my driver. It's a Buckpuck 3021-D-I-1000 and I attempted to wire in a couple switches with resistors to vary the light output. Unfortunately, upon powering I was left in the dark. I checked all of my connections (all good) but wasn't getting any power out of the driver despite a healthy input from the power source.

    So I started fiddling around with the wires and somehow managed to get the lights to flicker. I later determined that when I wired a connection directly from Vin+ to Ref and broke the circuit between Ref and Ctrl I could get light. It's very dim, but it's something.

    I can come close to understanding why I get light with voltage going to the Ref, but I'm having a lot of trouble understanding why I don't get light with the circuit wired as the technical documents show. I tried doing a simple power in/power out circuit without connections to the Ref and Ctrl pins, but got nothing.

    So, I guess my questions are: Did I just end up with a bad Buckpuck? And, is there any way to salvage what I have? (Maybe throwing a resistor in somewhere to get more power out?)

    Thank you in advance, I'm having a lot of trouble remembering the circuit courses I took...

  2. #2
    aka RossC
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    It is normal for a buckpuck to be at full power with open circuit between crtl/ref and off when there is a closed circuit with no resistor between crtl/ref.

    Have you checked the output from teh buckpuck.... ie, is it the puck, or is it a bad LED?

    What battery are you using and what are you driving with it? They may be other sources of probs.

  3. #3
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    I tested the LED out puts and got no current when the Ref and Ctrl had an open circuit.

    I'm attempting to drive four K2 Rebels (5.7W each) set in a parallel series of two LEDs. I read on Luxeon's site that my driver should be capable of sending current to six of these LEDs.

    My battery is a 11.7v Li-ion block.


    The LEDs all light up when I form a closed circuit between Ref and Vin+, so I don't think they're the problem. I'll try taking all but one of the LEDs out of the circuit later tonight and see if I'm just trying to do too much with the driver. (Is it possible that by forming a closed circuit between Ref and Vin+ I'm providing an artificially high reference and it's causing my driver to do more than it's supposed to?)


    Thanks for your help.

  4. #4
    aka RossC
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    I just did a quick google as I haven't played with k2's before.

    I saw 3.2 V listed as the Vf.

    so if you are trying to drive 4 in series, that would be 3.2x4 = 12.8 V

    Since you are using a buck driver, you need to have a battery with Vf of 12.8 +2 to get it to stay in regulation. The driver probably could run 6 of them but it would take a big battery to provide enough voltage.

    I think you would have more luck with less LED's in series. Try an experiment with a single LED plus the driver and see if that will light up?

    I don't think the closed circuit across ctrl/ref would cause any probs. I have done so often without any issue.

    Good luck.

  5. #5
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    I saw that too, and have two series of two LEDs in parallel, if that makes sense. So, and correct me if I'm wrong, I need a power source that provides 3.2x2, or 6.4 V.

    That being said, I disconnected two of the LEDs and I still have to connect Ref with Vin+ to get any light, and it's still pretty dim.

    I noticed a note in the technical document stating I would need a capacitor across the power supply leads if my distance between the driver and the source was over 18", which I think mine is. I don't have a capacitor, could this be the issue?

  6. #6
    aka RossC
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    Quote Originally Posted by sotak
    I saw that too, and have two series of two LEDs in parallel, if that makes sense. So, and correct me if I'm wrong, I need a power source that provides 3.2x2, or 6.4 V.

    That being said, I disconnected two of the LEDs and I still have to connect Ref with Vin+ to get any light, and it's still pretty dim.

    I noticed a note in the technical document stating I would need a capacitor across the power supply leads if my distance between the driver and the source was over 18", which I think mine is. I don't have a capacitor, could this be the issue?
    It is sounding more and more like the buckpuck is dead. How much greater than 18 inches is your lead? I have seen people on here use leads longer than 18 inches without any problems before, but if we are talking 6 M then perhaps that is the source.

    The buckpuck doesn't have reverese polarity protection. Is there any chance that your reversed the battery polarity at some point and fried it?

  7. #7
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    It's definitely possible that I inadvertently reversed polarity at some point during my, but I don't recall any specific moment that I had the battery connected and the leads switched around.

    Thanks for your help, I guess it's time to order a new driver and see if that solves the problem.

  8. #8
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    sotak, once in a while you get a dodgy Buckpuck, I got one last year with the same symptoms as yours. I got mine from Ledsupply and after I emailed them they sent me a new one.

  9. #9
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    Thanks for all the help guys! I ordered a new driver from LEDsupply and everything works great now.

    That being said, after reading a little more, I think my K2s are going to be replaced pretty quickly with something a little brighter. Good learning experience though.

    Thanks again.

  10. #10
    aka RossC
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    Quote Originally Posted by sotak
    Thanks for all the help guys! I ordered a new driver from LEDsupply and everything works great now.

    That being said, after reading a little more, I think my K2s are going to be replaced pretty quickly with something a little brighter. Good learning experience though.

    Thanks again.
    Happy Days,

    So where are the photos of the build and the beamshots?????

  11. #11
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    HA! Maybe that will come soon. Living in the city I don't have access to tools right now, so I had to special order a bunch of aluminum pieces pre-cut and am waiting on them to arrive. I just hope I have enough surface area to get rid of the heat. These things are getting dangerously hot really quickly just testing.

    But, I'll definitely post the results....eventually. Maybe a week or so.

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