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  1. #1
    Senior Member surreal's Avatar
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    Problem with B&M 4D Lite plus

    Hi.

    I tried searching; the BF search forum yielded very few results (as usual); googling with the "site:www.bikeforums.net" yielded tons of results, but none pertinent to my problem. So yes, I searched, no it didn't yield results, so I'm asking a question:

    Background: I have a Busch & Muller 4d Lite plus taillight mounted to my rear fender. It's been on my main commuter for about a year; maybe a little less. There are 4 LEDs in this light, but the 2 in the middle are no longer lighting. B/c I'm that guy, I have another B&M 4d Lite plus, so I connected the wires to the other light, and all 4 LEDs fired up, so I'm reasonably certain that the problem is in the taillight itself, and not in the dynamo, nor the wires leading from the dynamo to the connectors. Which leads me to my question(s):

    -Is this a common/known problem for this product?
    -How accessible are the guys of these things? I didn't just crack it open to have a look b/c I've never done so before and I wanted to get some background info before I tried.
    -Is this likely an easy fix, for a guy who isn't electronically inclined?

    The 2nd 4d Lite in my possession is intended for another project, but it wouldn't be a big deal to just replace the malfunctioning one, but it seems a wasteful shame to do that without even trying to revive it. Also, 2 of the 4 LEDs are still firing, and the light still basically works, ie, I'm still visible, but I'd like to be maximally lit-up whilst riding, so I wanna have a go at fixing the thing up. I'm just not really clear on how to go about it.....

    TIA,
    -Rob

  2. #2
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    It is probably a bad solder joint. If you open it up just check continuity with a multimeter. Use a magnifying glass and look for anything that may be cracked. The circuit can't be all that complex. Whether you can access it or not is a different story, sometimes you just can't.

  3. #3
    Senior Member surreal's Avatar
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    That's what I was thinking. I might try to crack it open, but I fear I'll do more harm than good. The 2 that work now are definitely "enough"; if I break the whole unit, I'll be SOL, but then I'll just buy another.

    Thanks for your response, Zacster.

  4. #4
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    In the past, if when the electronics of one of their lamps failed, B&M sent the customer a replacement circuit board for DIY installation. These days the lamps cannot be opened anymore, but this one looks like an older type. If you do not succeed on your own, you can email B&M - maybe they will help.

  5. #5
    Randomhead
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    I didn't have any problem opening my Seculite, so I would expect that opening this light shouldn't be much harder
    Randonneuring -- it's touring for people that aren't smart enough to stop for the night.
    It's a wonderful sport when you can make up for a lack of ability with a lack of sleep

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