Magicshine LED failure- Mtbr.com
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  1. #1
    Drinkin' the 29er KoolAid
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    Magicshine LED failure

    I decided to use my Magicshine for a city ride the other day and noticed that it didn't seem as bright as I remembered. At first I figured that was due to my eyes having gotten used to my lumen whore collection of 7up and 3up XPG lights. But then I noticed that the light would do this little flicker and dim slightly within about a second of being turned on from cold. Figured it was the driver, perhaps the sense resistors going bad, but after checking all that out and find nothing wrong I decided to put it all back together and when I powered it back up I realized that 1 of the 4 dies of the P7 was considerably brighter than the others. So it turns out that flicker is the 3 other dies dimming down.
    [Edit: It turns out that basically I was running on a single die at that point. Powering the LED with less current and examining closely I realize that the other 3 are not lighting up at all and it appears like the bond wires are partly detached from the dies]

    So what I think happened is the screws holding the P7 LED to the pill were loose, probably because the screw holes in the pill got stripped out during assembly, and this allowed the LED star to pull away and overheat enough to damage it permanently.

    So others might want to check those two little screws that are supposed to hold the LED tight against the pill. If they are loose, tighten them down carefully or replace with an appropriate size self-tapping screw as I had to do.
    Last edited by kwarwick; 12-10-2010 at 07:48 PM.

  2. #2
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    Sooo, what you're saying is that my Magicshinee might suddenly volunteer to be a host for an XM-L implant? That seems like a good thing.

    gerG

    edit: sorry, didn't mean to make fun of your misfortune. It does suck that your light gave out, and thanks for the useful tip. I am just looking for an excuse to tear my MS apart.
    Last edited by g3rG; 12-09-2010 at 08:23 PM.
    ...uphill uphill uphill DOWNHILL! uphill uphill uphill uphill DOWNHILL! uphill ...

  3. #3
    Drinkin' the 29er KoolAid
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    Quote Originally Posted by g3rG
    Sooo, what you're saying is that my Magicshinee might suddenly volunteer to be a host for an XM-L implant? That seems like a good thing.

    gerG

    edit: sorry, didn't mean to make fun of your misfortune. It does suck that your light gave out, and thanks for the useful tip. I am just looking for an excuse to tear my MS apart.
    No worries, I had a spare P7 star kicking around from a previous flashlight I upgraded to a SST-50 or something. Yeah, I've been eyeing the Magicshine as a potential host for a variety of emitter upgrades... was thinking a 3up XPG board even before the P7 bit the big one.

  4. #4
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    You know, it just occurred to me. "Magic-shine" is almost a synonym for "spontaneous-combustion". In retrospect that really explains a lot.

    Hopefully you will bring it back to life in an improved form.

    gerG
    ...uphill uphill uphill DOWNHILL! uphill uphill uphill uphill DOWNHILL! uphill ...

  5. #5
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    kwarwick,

    If you know what a sense resistor is, the rest of this may be old news to you.

    If you gonna open it up, do yourself a favor and upgrade some of the driver components.

    Replace the tiny 0805 sense resistors with some larger higher wattage 1206 parts. I'd look at two 0.15 ohm ones. The two resistors in the MS are the equivalent of a 0.08 ohm resistor and the two 0.15s will be 0.075 ohms. The MS never ran the P7 at 2.8 amps, 0.075 will run it at around 2.7 amps.

    Upgrade the diode to a 4 amp one (20 or 30 volt). The 2 amp one won't handle higher input voltages to the MS.

    Upgrade the input caps to some reasonably high voltage (30 volts?).

    If you have the older driver that uses an 8 pin SOIC mosfet, replace that as well with something decent. Look for a n channel mosfet with low gate charge, low Rds, a Vds of at least 30 volts, and able to handle at least 8 amps. If this description is greek to you, search for some of MtbMcGuyver's postings on the MS, I think he had suggestions for a good fet to use.

    By doing the above you can raise the voltage you drive the MS from. The SM5241 driver chip (6 pin SOT) is rated at 36 volts, but I'd never push it beyond 16 or so, it gets less efficient at higher voltages.

    If you have the version of the driver with 2 6 pin SOTs on it (one the driver, the other the mosfet), then I'd leave the mosfet alone, unless you are sure which one it is.

    If you do all the above, you should wind up with a MS than can run on any battery from 7.2 up to 14.8 volts, which is pretty handy. Of course the low voltage warning LED will only work right for 7.2 volt batteries.

    Mark
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  6. #6
    recognize the slowness
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    or you just rip out the driver and put in a h6flex. ;>)

    wish I had the skill to perform those kinds of changes...I can barely solder wires together
    "mountain biking and flyfishing, what more do you want?" - Yeah, I said it

  7. #7
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    Quote Originally Posted by jbflyfshr
    or you just rip out the driver and put in a h6flex. ;>)

    wish I had the skill to perform those kinds of changes...I can barely solder wires together
    lol I know what you mean.

    People talk about replacing those tiny components like it's nothing. I need glasses just to see them well.

  8. #8
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  9. #9
    www.hahntronix.com
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    kan3,

    I've never used a magnifier that large, but I often wear clip-on magnifiers, clipped to magnifying reading glasses. Everything beyond 12 inches is a blur, but it sure helps soldering down the legs on small smt chips

    I wouldn't recommend replacing current sense resistors in a magicshine if it's your first experience soldering. If you've done a bit of soldering and want to learn more about soldering small parts, the folks at http://www.sparkfun.com have a bunch of good tutorials on surface mount soldering. It's where I learned the hillbilly skillet reflow soldering technique.

    Mark
    Nimium est melior!

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