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LED strips not lighting up

Discussion in 'Troubleshooting and Repair' started by ChadVanHalen, Nov 22, 2015.

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  1. ChadVanHalen

    ChadVanHalen

    8
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    Nov 22, 2015
    So I bought this amp and the guy I bought it from installed these green LEDs, plugged it in and they were working
    [​IMG]

    He gave me the same 12v power supply and a couple days later the LEDs just didn't light up anymore. Nothing was dropped, nothing smells weird, just doesn't light up. Is there a somewhat simple fix? (I'm a guitarist so I have super basic soldering skills) or point me to a proper replacement strip that will work with the 12v power setup it came with?
    [​IMG]
    [​IMG]
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,482
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    Jan 21, 2010
    Check that you're still getting 12V from the power adapter. Do you have a multimeter to check it?
     
  3. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    It is highly unlikely that there is anything wrong with your LED strip. The connection of the LED strip to the power supply cable, the one covered with shrink tubing, is probably the culprit. Use a single-edge razor blade to carefully cut the shrink tubing off so you can inspect the soldered connections without damaging the underlying insulation on the wires. One or both solder joints has probably failed. As @(*steve*) suggested, if you have a multimeter see if there is 12 V DC between the two exposed connections to the LED strip. You will have to replace the shrink tubing with a few wraps of black electrical tape.
     
    Last edited: Nov 22, 2015
  4. cjdelphi

    cjdelphi

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    Oct 26, 2011
    First confirm you have an out voltage... if it was the led strip, they tend to fade before death unless the copper strip cracked....
     
  5. ChadVanHalen

    ChadVanHalen

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    Nov 22, 2015
    I don't own one, I should get one to have when working on guitars, I'll probably pick one up tomorrow

    And as you can tell by the picture I was attempting to cave man cut where the connections were and electrical tape it back up, but decided to ask for some advice before finishing... I'll continue that way and see if there's a cold solder joint or a dead connection somewhere then
     
  6. swagguy8

    swagguy8

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    Dec 10, 2014
    harbor freight tools has really cheap multi-meters ($5), they aren't that accurate, but works good enough to measure simple voltage.
     
    hevans1944 likes this.
  7. ChadVanHalen

    ChadVanHalen

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    Nov 22, 2015
    Thank you all for the replies

    I've been able to get back to working on it and looking at the two solder joints they don't look cold to my non experienced eyes
    [​IMG]

    So when I pick up a multimeter, likely later today, what do I set it to and what end do I touch where and what am I looking for? Thanks all for the help so far
     
  8. Bluejets

    Bluejets

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    Oct 5, 2014
    Set meter to DC volt range.......any range above 12v (most meters have a 20v range).
    One end of the black probe goes to Common socket on the meter.
    One end of the red probe goes to V socket on the meter

    Connect other end of the red probe to the plus sign on the strip and black probe to the negative.
    If 0 reading, no power getting to your LED strip.
     
  9. ChadVanHalen

    ChadVanHalen

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    Nov 22, 2015
    Very likely this is a stupid question... So I'm touching the multimeter ends to the wires soldered into the strip from the power adapter's socket, correct? Because putting them on the actual solder shows a 0 reading
     
  10. Bluejets

    Bluejets

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    984
    Oct 5, 2014
    If you get a reading of around 12v on the cables but not on the solder joints where the wiring enters the LED strip, then you have a break somewhere between the two.
     
  11. ChadVanHalen

    ChadVanHalen

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    Nov 22, 2015
    Ok, I'll have to strip the wires a bit to get to unsoldered bits...

    But while the supply is plugged in I noticed touching a small black thing labelled "151" every 3 LEDs lights up 3 LEDs while pressed, but not when the supply is unplugged. I can get a picture if that's too vague

    EDIT: I stripped away from the joint a bit and touching the red lead to the red wire and the black lead to the black wire while in DC voltage I get a reading of 0 as well
     
    Last edited: Dec 1, 2015
  12. Martaine2005

    Martaine2005

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    May 12, 2015
    The 151 things, are resistors.
    I think as already pointed out, no power to led strip, adapter is faulty.
    But I will add that sometimes boards are covered with varnish/resin.
    So you may have to use your probes to 'prick' the covering material to get a connection.

    If you push your meters red and black sharp ends into the soldered joint and still no meter reading.
    You either have a break in the cable from adapter to led strip or adapter is faulty!!

    Try another adapter, any 9v to 14v will confirm this.

    Martin
     
  13. ChadVanHalen

    ChadVanHalen

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    Nov 22, 2015
    Oh man, I tried a couple of my pedal board power supplies earlier and it didn't light up, didn't think to measure the voltage when I got the multimeter...

    So using a spare 9v my multimeter shows a reading of 8.87-8.91 on the bare wires where with the 12v the guy gave me it shows it fluctuating around zero... This means the fault is in the 12v adapter because while the 9v shows voltage in the wires it's not enough to power the strip... Correct?
     
  14. Martaine2005

    Martaine2005

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    May 12, 2015
    It seems you have discovered the wire to the leds is ok! So that only leaves the adapter itself. 9v wont power the strip. It is a little on the small side, if each led is 3.2v or 3.5v x 3. (9.6v or 10.5v)..
    I think you need to get your soldering iron out and a new 12v adapter.
    Have a look in charity/thrift stores for the box full of wires!!! You can probably get three or four adapters for $4.
    Get some that have a higher milli-amp output than the one you have. That might be what caused yours to fail..

    Martin
     
  15. ChadVanHalen

    ChadVanHalen

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    Nov 22, 2015
    Ok thank you... I checked the solder joint with the 9v and I got readings so that's good

    The one I was given is 500 mA, what mA should I be shooting for?
     
  16. Martaine2005

    Martaine2005

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    May 12, 2015
    Actually, 500 mA should be adequate for LEDs
    But without knowing the LEDs specifications it's hard to say.
    Just get anything with higher milli-amp output. 600, 700, 800 etc. The strip has current limiting resistors so no harm can be done.

    Martin
     
  17. ChadVanHalen

    ChadVanHalen

    8
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    Nov 22, 2015
    [​IMG]

    Thanks for the help everyone, I couldn't thrift shop since I have a big show Thursday, so I just got whatever 12v adapter Best Buy had and it has something like 1300mA... And, as you can see, voila! Up and running
     
    Martaine2005 likes this.
  18. Martaine2005

    Martaine2005

    3,331
    910
    May 12, 2015
    Glad you got it going...
    Have a read of post #2....:)

    Martin
     
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