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Unknown Fairchild Semiconductor component? Need for a new one.

Discussion in 'Datasheets, Manuals and Component Identification' started by Ville, Apr 30, 2011.

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  1. Ville


    Apr 30, 2011
    Hello everyone!

    I managed to burn this component inside charging controller of the solar panel system by accidentally mixing the battery cables. I now would have a need for a new one. Soldering is not a problem, it seems that everything else is ok inside the controller. As I didn't have opened this device before I do not have a part number but there is still something visible.

    What I have been able to find out this seems to be Fairchild Semiconductor part. Part number seems to start with 753 but that is where I'm stuck.

    Here is couple of high res pictures of the burnt component:

    I have already contacted also the device manufacturer about the component but usually they aren't so helpful when it comes to changing components inside the device they have manufactured.

    I have to say that I was pretty surprised that this device has quite many fuses but none of those seem to protect about the wrong connection. Will have to add a fuse to the battery cable.

    Best regards
    Ville from Finland
  2. davenn

    davenn Moderator

    Sep 5, 2009
    dunno mate, too badly damaged could be anything

    the part # is more likely the one starting with N to the right of the big F
    there's no other Semi's in the unit that look like this one ?

  3. Ville


    Apr 30, 2011
    Thank you for a reply. This is the only one that is attached to the same heatsink:

    There is small scratch which make reading a bit harder. Scratch is from the small clip which held these to heatsink. These were also attached with a thermal tape.

    The readings on this one seem to be:


    On the first component which I'm tracking down next to the big F (Fairchild logo) seems to be only NU3 if I'm correct. Which I have understood to be something like manufacturing factory code.

  4. Resqueline


    Jul 31, 2009
    Those pic's were so big & slow in loading that I cropped them to just the item in interest and attached them here. Maybe you'll get more responses that way.
    Being a TO-220 device in a solar panel charger/regulator it has to be a Schottky diode or a MOSFET transistor. If there's no relay around I'd say it's a MOSFET.
    Straighten up the device and shoot a pic of the whole board from straight above (and below too) so we can see the other parts and the PCB tracks going to it.

    Attached Files:

    Last edited: May 1, 2011
  5. Ville


    Apr 30, 2011
    I took a picture of the board but taking a picture from the other side seems hard. There is two switches which has been installed to device cover and then soldered afterwards to board. So I would need to unsolder those switches to see to the other side. Not a hard thing to do but wouldn't like to as I can solder new components without doing that.

    I however managed to see all the components so I made photo with text to tell which pins belong to what. Hopefully this will give enough info and if not I'll then see how to get more info.

    Here is datasheets of the known components:
    Bourns 3296
    B1645 Schottky Barrier Rectifier


    Attached Files:

  6. Resqueline


    Jul 31, 2009
    Ok, I understand your concerns. Try to draw where the (wide) tracks on the other side are going to & from the tracks marked with red squares then.
    In particular the width & locations of the tracks from the mystery component is of interest.
    I am inclined to believe it's a MOSFET used to switch on & off the charging, since a relay is not mounted on the PCB. Just need to verify, and check if it's an N or a P channel.
    The blue Bourns things are trimmer pot's, probably used to adjust voltage & current levels.

    Attached Files:

  7. TbirdMan


    Apr 17, 2011
  8. WHYSguy


    Nov 2, 2018
    in situations like this where you have a burnt component with some markings semi readable, taking a good high res picture then messing with the contrast/tint/color temp... setting in an image editing program can reveal more of the markings than is able to be seen initially.

    I doubt that you are still hung up on this project so I suppose I'm posting for the benefit of others.
    debe likes this.
  9. kellys_eye


    Jun 25, 2010
    Dragging up a post that's 7 years old?????

    Pretty good assumption......:rolleyes:
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