Gemini Duo died - get a Nitefighter BT21, BT40S, or.....?- Mtbr.com
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  1. #1
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    Gemini Duo died - get a Nitefighter BT21, BT40S, or.....?

    My setup for the past 2 years has been a Gemini Duo on the bars and an original Yinding on the helmet. I am running 4 cell 18650 Hunk Lee battery packs, standard non-threaded Magicshine type connectors.

    The Duo recently died on me. While I've been generally satisfied with the setup -- and the Yinding is still going strong -- I think I may go with a whole new setup. I want to switch to lights with warmer/neutral tints, I'm tired of the cold tints. (I could still keep the Yinding in service, but I don't want to mix cold and warm tints.)

    I haven't been looking at lights for the past 2 years, so I've been out of the game. Looking at the current threads, the Nitefighter BT21 and BT40S seem to be the top budget lights these days.

    Any recommendations for a new setup - BT40S on the bars, BT21 on the helmet (or vice versa), or two BT40s, or two BT21s? Something else?

    Will the Magicshine connectors on my Hunk Lee packs fit the Nitefighter lights? If not, any source for Nitefighter-compatible female cables or adapters?

  2. #2
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    Quote Originally Posted by zuuds View Post
    The Duo recently died on me.
    Just curious: what namely happened? Is it damaged beyond repair?

  3. #3
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    Quote Originally Posted by -Archie- View Post
    Just curious: what namely happened? Is it damaged beyond repair?
    Actually I don't know. The Duo turns on and off, both LEDs illuminate equally, the low/mid/high function works, the programming function works, but the output of the light has dropped dramatically, it is only about 10% of normal. During a ride, it was working normally, but then all of a sudden the light output was almost nothing. When this happened the light was cool to the touch, so it was not the heat protection circuit kicking in. I ruled out overheating, the battery, and accidental programming as being the cause, so I'm guessing something went bad on the circuit board?

    I may still send it to Action LED to see about repairing it, but it's two years old, and is the older version with XM-L (not XM-L2) emitters, so it may be "totaled" from a financial standpoint - i.e. if it's going to cost $40-50 to fix I'm probably better off just getting a new light.

  4. #4
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    Yes, that seems like driver failure indeed...

  5. #5
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    MJ808 lights do this when one of the leads on the inductor breaks. Possibly the same on your Duo
    GoPro adapters for bike lights http://www.pacifier.com/~kevinb/index.html

  6. #6
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    If you get a Yinding with Neutral white and the 10-step KD driver you basically have a Gemini Duo.

  7. #7
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    Quote Originally Posted by Ofroad'bent View Post
    If you get a Yinding with Neutral white and the 10-step KD driver you basically have a Gemini Duo.
    Hmm, maybe I should just pick up two of those driver boards to fix the Duo and upgrade the Yinding.

  8. #8
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    Quote Originally Posted by zuuds View Post
    Actually I don't know. The Duo turns on and off, both LEDs illuminate equally, the low/mid/high function works, the programming function works, but the output of the light has dropped dramatically, it is only about 10% of normal. During a ride, it was working normally, but then all of a sudden the light output was almost nothing. When this happened the light was cool to the touch, so it was not the heat protection circuit kicking in. I ruled out overheating, the battery, and accidental programming as being the cause, so I'm guessing something went bad on the circuit board?

    I may still send it to Action LED to see about repairing it, but it's two years old, and is the older version with XM-L (not XM-L2) emitters, so it may be "totaled" from a financial standpoint - i.e. if it's going to cost $40-50 to fix I'm probably better off just getting a new light.
    I had the exact same symptoms with one of the first Gen Xera's as you are having. All the functions worked perfectly but at very low output. It's been a few years but if I remember correctly Gemini told me it was a failed driver. All other Xera's and my Duo are still working fine.

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