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  1. #1
    mtbr member
    Join Date
    Jun 2008

    Magicshine Voltage question


    I am now on my 2nd Magicshine MJ808-E. I purchased this last one from GeoMan last year, but see they have gone out of business.

    My light stopped working last night during a ride. The LED for the toggle button still works and is on though.

    I disassembled the light head, and measured voltage at the circuit board where the white LED is soldered.

    I believed the LED was dead. I desoldered the LED and tried powering it with 3V, and nothing.

    I measured voltage across the 2 terminals where the LED was soldered, and toggled through all 3 settings.

    I get these voltages:

    Do these seem right, or too high? I was going to buy another CREE XM-L and replace the one that burned out, but I don't want to do that if I'll just burn a new one out.

    Neutral-White Cree XM-L Star LED - LED
    Name:  creexml-nw260_med.jpg
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  2. #2
    mtbr member
    Join Date
    Apr 2010
    With 3V the LED should be very bright, so it's probably dead. If you have DMM set it diode testing and try on the led, it should give a faint glow. Since the current regulator is switching step-down regulator, you can not measure voltage without load. Since you've tried it, you might have ruined the driver too. I'm not sure MS drivers have open circuit protection. Wire a 5W resistor instead of LED and measure the voltage drop over resistor if you don't have spare led. If you're reading strange voltages, then the driver is wonky too, so while you're at it and you're ordering a new LED, order a spare driver with it.

  3. #3
    mtbr member
    Join Date
    Jun 2008
    Thanks Toaster.

    So I guess I should just expect to see 3V if I measured across the LED when it was powered?

    I went ahead and ordered just the new LED + board for $15 after shipping. Hopefully a cheap fix, but it will probably just burn out again knowing magicshine..

    I also ordered a brand new light; Fluxient 1xU2 after reading some reviews because I'm through with Magicshine after this one.

    I've had 2 magicshines over 3 years and every single year something fails. I've had the battery circuit fail, the jacketing on light head melt and short out, and now finally the LED burn out.

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