LED panel lights from china

Discussion in 'General Electronics Chat' started by Mr.Beard, Feb 1, 2015.

  1. Mr.Beard

    Thread Starter New Member

    Jan 23, 2015
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    0
    Has anyone purchased and played around with these lights?:
    http://www.ebay.com/itm/36110704764...49&var=630448321372&ssPageName=STRK:MEBIDX:IT
    Just one example.

    You can buy them everywhere from all kinds of different sellers and they all look like they were made in the same factory somewhere in china. I think they may be like what was being talked about on this thread:
    http://forum.allaboutcircuits.com/threads/led-panel-light.100786/
    Each is a ring of LEDs, a diffuser and reflector that attach to a driver that takes a huge range of AC voltage. I have been using them all over my renovation. They are really neat when you think about the simplicity.

    Does anyone know how the drivers are designed to be so small and take such a huge input range? I assume the driver consists of a voltage rectifier circuit and transform with some other capacitors and voltage regulation thrown in. I have opened one up and poked around but I am not sure what all I am looking at.

    Also I had one malfunction on me. When powered on the fixture slowly fades in while flickering and continues to flicker at a pretty slow (respectively) frequency for a long time (hours) before finally fully illuminating. What could be failing in the driver to cause this? I have been theorizing that it might be a bad capacitor but like I said before I am not sure what they consist of.
     
  2. #12

    Expert

    Nov 30, 2010
    16,343
    6,828
    It's called a switching power supply. I'd say you have no chance of repairing one because half the people that are good at electronics would find it difficult. They are fast, they are picky, and they often do what I call a cascade failure where one part shorts and takes out a few more. They should be fairly inexpensive, especially compared to the week it would take you to understand and troubleshoot one.

    However, capacitors are cheap and you are free to experiment if that's what you like to do.
     
  3. MikeA

    Member

    Jan 20, 2013
    125
    17
    I bought a few of them, 18W ones. Took apart both the lights and the power supplies of course. :D
    All the insides were marked with 12W. Counted the number of LEDs, multiplied by 0.5W = 12W. :rolleyes: Power supply marked 12W inside too.

    Real power between the power supply and the lights 9-10W. Terrible power supply soldering job. Redid a few points. But they all worked out of the box, and no trouble from them at all. They are not UL listed as far as I know and quality control is bad. I don't know if I'd like to have dozens of them hard wired inside a house.

    Plastic enclosure of the power supply is flammable. :eek:
     
  4. snav

    Active Member

    Aug 1, 2011
    100
    10
    I've been playing with the components and LEDs for a year or so, lately I've noticed they are coming through with a pigtail fuse soldered at the input at least. 10w drivers can be had for under a buck if you are patient.
     
  5. Lundwall_Paul

    Member

    Oct 18, 2011
    220
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    My guess is that they were not UL marked because they either didn't pass UL certification or they knew that it wouldn't pass.
     
  6. JWHassler

    Member

    Sep 25, 2013
    201
    33
    ... or they didn't care
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    When I made my living servicing PC monitors - I got the impression that the more safety symbols printed on the back, the more likely it was to catch fire!
     
  8. Mr.Beard

    Thread Starter New Member

    Jan 23, 2015
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    Thanks for all the leads on information #12 and MikeA. The first thing I did when I got my first fixture was to dismantle it too. Everything seemed straight forward enough and knowing where I was going to put them there was little fear in using them. After the one began to malfunction I never dreamed I would be able to fix it. I was mainly curious about how the circuit worked and to figure out how the effect was being created. I didn't know the drivers were called switching power supplies so getting that piece of info really helped me understand what is going on. Thanks. Though I still don't have a theory for why the driver was doing the fading/flickering but I am working on it in my limited free time. Now I am thinking that maybe the output rectifier failed making it like a false half wave with just enough juice to charge the filter/capacitor and light the LED array in a flicker state. And that over time it is able to "catch up" to the full capacity of the capacitor enough so that the array is always powered. How does that sound to anyone? Just some pondering that usually is accompanied by a pitcher of beer in the middle of the table.

    The company agreed to send me a new driver as this is a common problem for these kinds of mass made non-UL products from child factories in China. Fun.
     
  9. johnma33

    New Member

    Jul 23, 2015
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