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Identify blown IC without circuit diagram

Discussion in 'Datasheets, Manuals and Component Identification' started by Ridgeau, Nov 17, 2018.

  1. Ridgeau

    Ridgeau

    6
    0
    Nov 17, 2018
    Hi all,
    I am new here so let me start with, Hello.

    I have a friend who dropped off a LG receiver Model w3-2, the unit will not power up and or display wireless ready LED.

    I have opened the unit and done some fault finding which has lead me to a blown IC, it seems a bug has crawled across the pins and blown the chip.

    My dilemma is I am unable to locate any circuit diagrams for the board, and the chip is blown in such a way that it no longer has identifiers visible on it.

    Is anybody familiar with this board, or know how to identify a chip which is blown.

    I have attached a couple of photos.

    Any help will be much appreciated.

    With thanks:)
     

    Attached Files:

  2. Bluejets

    Bluejets

    3,452
    698
    Oct 5, 2014
    Sadly I doubt it was a bug crawling around, more likely a short somewhere to blow the complete top off the ic like that.
    Looks like a smps chip but just which one would probably be a guess at best without a schematic.
    You don't say what sort of "receiver" either.
     
  3. kellys_eye

    kellys_eye

    4,284
    1,145
    Jun 25, 2010
    That device is indeed a high side SMPS controller with its own MOSFET switching transistor in an 8-pin DIP package.

    You could use the parametric search facilities at a component supplier site (like Digikey) and search using those factors to get the list down to a 'few' potential replacements.

    Then you'd need to compare the actual circuit layout and component parts against the datasheets for those devices and (hopefully) any schematics they include - quite often the devices are used exactly as the datasheet recommends, right down to the component values, and you'll have your answer.

    Someone on here may be inclined to assist further with this method but we'd need to see the track side of the component board in order to go any further.
     
    Ridgeau likes this.
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,178
    2,690
    Jan 21, 2010
    If you're really lucky, the top of the IC will be rattling around in the case somewhere. You may be able to read some markings.
     
    Ridgeau likes this.
  5. davenn

    davenn Moderator

    13,260
    1,748
    Sep 5, 2009
    tho you can see a bug, looks like the remains of an ant, between 2 of the pins ;)


    yes he did :)
     
    Last edited: Nov 17, 2018
    Ridgeau likes this.
  6. Ridgeau

    Ridgeau

    6
    0
    Nov 17, 2018
    Thanks all for the replies, I am thinking with the time involved to find the correct IC and the age of the unit, that I have advised he upgrade his system.
    I did mention if he knows of anybody with the same unit we can use that for a Schematic.

    davenn, thanks for the observation with the insect still stuck there, first time I have seen this, Ant nests yes but single little bug Hmm.

    Cheers all , back to my next job.:)
     
  7. Bluejets

    Bluejets

    3,452
    698
    Oct 5, 2014
    Yes, did see that but when one considers the damage to the chip, do you really think the bug bits would still be there in any way shape or form? Have yet to see a bug that can conduct that amount of fault current.
     
  8. 73's de Edd

    73's de Edd

    2,677
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    Aug 21, 2015
    Sir Ridgeau . . . . .


    If you will give a good photo of the foil paths of the other side of the board . . . I am HEAVILY thinking that is going to be a cheap and easily available VIPer22 series of unit .
    Usually the other manufacturers like type of units mechanically drop out a pin for high voltage physical isolation at that corner of the PCB and sometimes even cut out an isolative slot in the pcb.
    That corner of the board is where that ant wouldn't want to stop and pee, as that is where he would catch the FULL FURY of the high voltage feeding into that chip.
    The only other thing to confirm, is that if that IC's internal FET failure might also have taken out the line fuse up near the AC input plug and the black, rectangular FWB rectifier, that is right beside input line surge thermistor TH902.

    PROBLEM AREA . . . . .
    Your afflicted area is being within and is being responsible for the systems standby power supply section , which, if the unit is plugged into and AC outlet . . .is then running 25 hrs a day !.


    PRELIMINARY HINT . . . . .

    Before I even get to see the requested info . . . .
    Of the 8 pins on the IC, CO-JOINED pins 1 and 2 will be going to the main power filter Negative.
    while pins 3 and 4 will be receiving individual circuitry components.
    AND THEN, WITH THEM BEING VERY VISIBLE, is that all of the IC's other sides pins of 5-6-7-8 will be co-joined and going to a primary winding terminal on the smaller JELLO AND BLACK switch mode power transformer.



    73's de Edd
    ...................

    HEY ! . . . . I'm not losing my hair . . . . . . I'm just getting more head !
     
    Last edited: Nov 18, 2018
  9. Ridgeau

    Ridgeau

    6
    0
    Nov 17, 2018
    Thanks 73's de Edd,

    Mains too both sides of Fuse was all good.

    I will pull the board out and upload some photos.

    Bluejet:"We make our creatures tough here in Australia" It probably died because it was stuck...:):)

    Ridgeau
     
  10. Ridgeau

    Ridgeau

    6
    0
    Nov 17, 2018
    Okay 73's de Edd,

    Track side of board as requested.

    [​IMG]

    X marks the spot.

    Let me know what you think.

    With Thanks

    [mod edited to include pic inline]
     

    Attached Files:

    Last edited by a moderator: Nov 20, 2018
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