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LED power supply thermal fuse blown

Discussion in 'Troubleshooting and Repair' started by davidjk, Oct 22, 2014.

  1. davidjk

    davidjk

    5
    0
    Oct 2, 2014
    hi again,
    i have a 12v 6amp LED power supply that does not work. i opened it up and i can see that what appears to be a thermal fuse that appears to have blown
    The LEDS are a 5 meter 5050 300 LED and apparently draw 2 amps.
    i am happy to replace the fuse, but i do not know what rating to get. the glass surround is shattered and unreadable
    could you if possible let me know what rating thermal fuse to get

    the power supply is an ly 1206
    http://www.pchub.com/uph/laptop/659-130555-27361/PCH-OEM-Power-AC-Adapter-Compatible.html

    This is the Fuse i mentioned
    IMG_0083.JPG
    and the power supply
    IMG_0085.JPG

    Many thanks
     
    Last edited: Oct 22, 2014
  2. Bluejets

    Bluejets

    3,532
    716
    Oct 5, 2014
    Says 1.6A on the back cover photo.
     
  3. davidjk

    davidjk

    5
    0
    Oct 2, 2014
    that is the input, the output is 6A
     
  4. Bluejets

    Bluejets

    3,532
    716
    Oct 5, 2014
    Fuse to me looks to be located very close to the input.
    Output is down the other end.
    Other than that, what is you query about then..? i.e. you already seem to know your answer
     
  5. davenn

    davenn Moderator

    13,345
    1,774
    Sep 5, 2009
    OK so you want a fuse rated at 240VAC and ~ 1.5A
    it isn't a thermal fuse, as you have already stated its glass encapsulated and also it isn't in contact with any components

    Be aware that replacing the fuse may see its instant demise as well because of a fault further into the circuit
    possibly the bridge rectifier which appears to be located between the heatsink and that large electrolytic capacitor towards the top left corner of pic 2

    Dave
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,213
    2,695
    Jan 21, 2010
    Yeah, I'd replace the fuse and then measure the resistance across the mains pins. (with some experience you can do this before replacing the fuse, but measuring across the correct points on the board.)

    If the resistance is very low (and stays that way) then a failed bridge rectifier is one option. It's also possible that the mosfet has failed. Both of these are relatively easy to diagnose.
     
  7. davidjk

    davidjk

    5
    0
    Oct 2, 2014
    thank you , i will give it a try.
     
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