Hard Part to find for such a simple solution

Discussion in 'The Projects Forum' started by Juan Pablo, Dec 23, 2014.

  1. Juan Pablo

    Thread Starter New Member

    Dec 22, 2014
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    Hi All! Juan Pablo.

    It's been a while since I've had to track down a hard to find part to fix a circuit. I know someone here has the answer! I'll get right into it.

    Circuit: Black Diamond storm headlamp (some rain got in)

    Part [known]: It is a diode. It is a tiny rectangle. It is an on-board design. It has three prongs--two on one side, one on the other. Written in large letters and horizontally is 'KL1'. Written adjacently and vertically in smaller letters is 'Y9'. I went to my local store. We couldn't identify the part .

    Part [best guesses]: It's a Schottky diode. It is of SOT-23 packing. The device name BAT45 comes up a lot in my web searches.

    It's a three second solder job if I can get exactly the right part. I hope someone on here can shine some light on this issue.

    Thanks so much!!!!
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,421
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    Sounds like a transistor. You will have to post a clear well focused photo of the circuit board.
     
  3. KJ6EAD

    Senior Member

    Apr 30, 2011
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    Last edited: Dec 23, 2014
    MrChips likes this.
  4. Juan Pablo

    Thread Starter New Member

    Dec 22, 2014
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    Last edited: Dec 24, 2014
  5. KJ6EAD

    Senior Member

    Apr 30, 2011
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    I started by knowing that those types of headlight circuits are usually buck converters that incorporate a Schottky diode so I was biased in that direction.

    I looked up the marking code you gave us on a few websites that have listings of SMD marking codes and many of the references matched the KL1 portion to a BAT54.

    I then looked up some of the BAT54 data sheets from common manufacturers of diodes such as Vishay, MCC and Diodes Inc., knowing that companies like Princeton Tec and Black Diamond make large margins on their high quality products and won't source parts from unreliable sources.

    I scanned said data sheets for marking codes that coincided with the complete format of your code.

    That's all there is to it; a synergistic combination of prior knowledge, educated guesswork, research and luck that sometimes succeeds.
     
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