LED dimmer question/problem

Discussion in 'Lighting' started by rakabos, 9 Aug 2011.

  1. rakabos

    rakabos

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    I bought some LED strips on Ebay and they arrived the other day, I wanted to use them as moonlights. The problem is they are a bit bright. So i bought a dimmer and connected it but the lights do come on at all now. Im no electrical ghuru and advice would be appreciated.

    Here is a pic of the dimmer:
    34494e40fa4fef086.jpg



    Here is a pic of the power supply for the LED strips:
    34494e40fa708dfef.jpg
     
    Last edited: 9 Aug 2011
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  3. Loki

    Loki cable tie ninja

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    if you have a multimeter you could check if you actually seeing voltage on the output side of the dimmer.
    maybe the pot is broken?
     
    Last edited: 9 Aug 2011
  4. OP
    rakabos

    rakabos

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    I will have to borrow one, so the two units would work together in theory at least?
     
  5. Loki

    Loki cable tie ninja

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    I'm no guru but i don't see why not.. only visible diff is the amperage.
    Your adapter is pushing more than the dimmer can..
    unless i'm reading it wrong and the dimmer can handle 8A not .8A
     
    Last edited: 9 Aug 2011
  6. viper357

    viper357 Admin MASA Contributor

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    Have you got your positives and negatives the right way around? On both ends.
     
  7. viper357

    viper357 Admin MASA Contributor

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    Or it could be the dimmer switch is too powerful, because the LED's are hardly drawing anything the dimmer could just be absorbing the milliwatts from the LED's and not pushing anything out, well that's my technical explanation. :p

    What I did was bought one of those cheap multi-voltage adaptors, then I just dropped the voltage to either 4.5v or 6v I think. That reduced the brightness perfectly.
     
  8. lIghty

    lIghty

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    Rakabos, It could be several things.

    Things to check:

    1 - If you connect the lights directly to the power supply, do they still lights work?

    2 - Try establish the polarity of the cables coming out of the supply, if you don't have a multimeter, you can just tie up a piece of old wire to the supply's low voltage output wires and put the wires into some salt water, the negative wire will be the one fizzing. use a separate piece of wire, as it will cause the wire to oxidise and damage the cable. from this test you can find the polarity of the LED wire, as + goes to +.....

    3 - Now try connecting it up again making sure that the polarities are connected correctly.

    4 - If this still doesn't work, the dimmer unit may be damaged or it may not have enough load on it for it to work correctly? it is a bit confusing with the .8A or 8A?

    5 - If you can open the unit and submit pictures of the board and components I might be able to get an idea of the circuit used, there should be a small screw holding the knob onto the shaft, just remove the know and then loosen the 4 screws to open (I think)

    Hope this helps!
     
    Last edited: 9 Aug 2011
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  9. OP
    rakabos

    rakabos

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    The + and - are the right way around :p

    I can try the above, that should also work, but already dropped cash on the dimmer....
     
  10. OP
    rakabos

    rakabos

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    Comments above
     
  11. lIghty

    lIghty

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    Ok, let me know.

    its quite possible to be 8A, most likely the ciruit is a 555 with a driving transistor.
     
  12. OP
    rakabos

    rakabos

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  13. viper357

    viper357 Admin MASA Contributor

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    Test the dimmer with a light bulb from your car.
     
  14. OP
    rakabos

    rakabos

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    Gonna test it with a coffee table light quickly
     
  15. lIghty

    lIghty

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    Aggghhhhh, itsn't that 220V volt??????

    Don't otherwise you going to K@k yourself when it goes BANG :whistling:
     
  16. lIghty

    lIghty

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    Ok,

    U1 is a NE555. can you see the part numbers on U2 and the big transistor at the top, the black thing with the 3 legs facing down and a metal tab facing up.
     
  17. OP
    rakabos

    rakabos

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    The 3 legged: DG32AD / FDP / 6670AL

    What else you need?

    I found this in my toolbox, what should i set it to, to test the output?

    34494e4114158e939.jpg
     
  18. lIghty

    lIghty

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    3924e41159aa52d2.jpg

    Test voltage between the input pins and the output pins, but while testing the output, turn the knob.

    will come back to you in 5.
     
  19. OP
    rakabos

    rakabos

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    The freaking power just went off arrghghhhhhhhhhhhh!!!!
     
  20. OP
    rakabos

    rakabos

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    So i must plug in the LED Power supply, run it to the input on the dimmer and test the output with the multimeter?
     
  21. lIghty

    lIghty

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    Ok,the mosfet is rated for 80A, but the board would fry by then, so its more likely designed for 8A.
     

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