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Sequential Tail Light

Discussion in 'LEDs and Optoelectronics' started by Rustyroof, Dec 2, 2016.

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  1. Rustyroof

    Rustyroof

    13
    1
    Dec 2, 2016
    IMG_0163.JPG Hi,
    I am working on a little project and wanted an led arrow. I found an led trailer light assembly, this is exactly what I was looking for. I looked on the company's website and the answer to a question was..... this is not sequential....... again... just what I wanted. I started hooking this up and found out that this is sequential. Is there an easy way to make this not sequential. I can't return it, as I already cut a wire, I just want all leds to light and stay on when power is on.

    Thanks
     
  2. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Well... that black IC on top. Can you provide a part number on it?
    You may be able to simply jumper a couple pins together and call it done, but I can't suggest what pins without identifying the parts on the board, and potentially where the traces go.
     
  3. Rustyroof

    Rustyroof

    13
    1
    Dec 2, 2016
    CDT7350-02
    1421
     
  4. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    It's hard to find english resources for that...
    But pin 3 is labelled as 'ALLON' and accepts a logical high voltage to enable.
    This sure *sounds* like it will turn all of the LEDs on, but without one to test with I can only provide this is generic advice.

    How many wires to the lamp? 2, or 3?
    You may be able to short pins 1 and 3 together which should simply turn all the LEDs on at once... but if the designer grounded pin3 instead of letting it float you will short out your supply. Alternatively, you may actually need to disconnect pin 2 and move the connection to pin 3... unsure at the moment.
    If you are able, grab a multi-meter and keep the black probe on the negative wire.
    Set it to resistance, and poke and prod at pins 2, 3, 7 and 9.
    If you have a 3-wire setup, keep the black probe on the 3rd wire (signal) and poke/prod the same pins again.
     
  5. Rustyroof

    Rustyroof

    13
    1
    Dec 2, 2016
    Thank-you very much for your help. It may take me a couple day to revisit this, but there are 3 wires to this unit, but one does nothing. I think they have a similar assembly that looks similar but has other lights in it, and that's why there is the extra wire. I have tried supplying the 12v to this wire and nothing happens, and I have supplied 12v to both at the same time and nothing changes. This is a sealed unit, and I will need to open it, without destroying it, and being able to re-attach the lens. I will try to open it and check the resistance on those pins.

    Sort of a newbie here, how do I know the number of the pins?
     
  6. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Take care opening that thing up.
    As far as pin numbers are concerned, take a close look at the chip and look for a 'dot' or marking.
    These packages have a little notch cut out of one end of the chip, if not you should find a small dot. Start at this mark, and begin counting pins moving counter clock-wise.
    In this case, pin one is the closest pin to the U1 marking on the board.
     
  7. Rustyroof

    Rustyroof

    13
    1
    Dec 2, 2016
    I was able to remove the cover and use a multimeter. I attached black to ground wire, and at each probe of the ic I got.....
    1- 640
    2-804
    3-805
    4-779
    5-783
    6-816
    7-630
    8-1.5
    9-795
    10-806
    11-806
    12-806
    13-805
    14-805
    15-761
    16-761
     
  8. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Excellent!
    Looks like pin 8 is tied to ground, which is as expected.
    This also means that the pin we want to manipulate is *not* connected to ground so we should not have to worry about about accidentally shorting out the power supply.

    Next step is to repeat the process (but much less steps).
    Put the black probe on the 'power' wire of your lamp and check pins 1, 2, 3, 7, 9.
    Pin 1 should read something tiny.
    Pin 3 'might' vary if you leave the probe on long enough...

    After this set of measurements, the next step *might* be shorting pin 3 to pin 1. (hopefully)
     
  9. Bluejets

    Bluejets

    4,596
    975
    Oct 5, 2014
    Given this short video, possible to change by pin selection.


    Japanese but possibly follow parts of the below pdf.
     

    Attached Files:

  10. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    That's the hope.
    Pin 3 is an 'ALL_ON' mode selection pin, that appears to over-ride the function of the other pins.
    As long as the pin is not externally grounded, it would be incredibly easy to put a dab of solder or a small jumper wire on it to connect it to 12V...
    That being said... I'm still incredibly curious what the third wire is for...

    I should have verified that the only two wired used is Ground and Power and the sequencing happens automatically.
     
  11. Rustyroof

    Rustyroof

    13
    1
    Dec 2, 2016
    Thank-you all for helping me on this. Yes, there are 3 wires, but as far as I can see the third wire does nothing. Also as soon as I apply 12vdc to the red power wire the lights flash automatically.

    I put the black lead on the power wire, but there is absolutely no reading on any probes 1-16 of the ic.:confused:
     
  12. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Hrm.. well, not as simple as I thought but let's keep going.
    Now that you have it open, are there any other parts on the back-side of the board?
     
  13. Rustyroof

    Rustyroof

    13
    1
    Dec 2, 2016
    This is a pic of the back side
    IMG_0164.JPG
     
  14. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Well. I see diodes back there.
    That may have been our problem.
    Put the red lead on the power wire and repeat the last step ;)
    Do you have a soldering iron?
     
  15. Rustyroof

    Rustyroof

    13
    1
    Dec 2, 2016
    There was no difference. Absolutely no reading when I put the red probe on power wire and used black on the leads of the ic.

    Yes I do have a soldering iron.
     
  16. Bluejets

    Bluejets

    4,596
    975
    Oct 5, 2014
    Meter on diode test?
     
  17. Rustyroof

    Rustyroof

    13
    1
    Dec 2, 2016
    I am not sure I know how to do that.
     
  18. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Well. If set to measure resistance Ω, your meter should have shown something on the pins of that IC...
    Can you please snap a picture of your meter and the current setting you used so we can confirm what you used?
     
  19. Rustyroof

    Rustyroof

    13
    1
    Dec 2, 2016
    IMG_0906.JPG
    It doesn't matter if I have it on 200, 2000......all the way to 20M. I have tried red from meter on red (power on light) and used black from meter to probe the pins of ic, and I have tried black from meter on red (power on light) and used red from meter to probe the pins and all have no reading, also yes my meter is working as when I touch my red and black together I get 1.2 ohms.
     
  20. Bluejets

    Bluejets

    4,596
    975
    Oct 5, 2014
    Red angle banana plug looks like its almost broken off...
    perhaps intermittent..??
    could be wrong but it looks like the 2000 scale is for diode test
    also you have the red test lead connected to the common........
     
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