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  1. #1
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    820-00875 A1708 no power stuck on 5V

    Hi community!

    I am back in business with a problem on this board. Found out that PP3.3V_G3H is missing. Found a shorted capacitor C6991 on input voltage of U6990. After i swap the C6991 i got only 2.2V instead of 3.3V on output. I injected 3.3V and 20V were there. Now i dont know what the problem is. If there would be a short i woul not get 20V after injecting 3.3V.

    Any ideas?
    THANKS!

  2. #2
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    Re: 820-00875 A1708 no power stuck on 5V

    I am not very familiar with these boards, but you are essentially saying that the PP3.3V_G3H is now 2.2V. But when you inject 3.3V, you get normal 20V..?

    In that case, I would check the resistance to ground on PP3.3V_G3H line, and if checks okay (is not too low), then next, I would check the circuit that is generating it, it could be damaged as it had outputted to a shorted load.

  3. #3
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    Re: 820-00875 A1708 no power stuck on 5V

    Thank you mitchW!

    i meassured the resistance in diode mode and got 0.362. Donīt know if it is to low in this case. I will now check the other components of the circuit

  4. #4
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    Re: 820-00875 A1708 no power stuck on 5V

    0.362 is probably okay. I would compare this to a known good board.
    Do a measurement in ohms.

  5. #5
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    Re: 820-00875 A1708 no power stuck on 5V

    Hi! I was checking the whole circuit with no result. I even changed the U6990 and checked all the FB lines etc.. All good! Still only 2.2V on output.

    No ideas anymore.

    Someone with a good idea?

  6. #6
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    Re: 820-00875 A1708 no power stuck on 5V

    Check U6990 (which you already did), D6901, R6991, U7000.

  7. #7
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    Re: 820-00875 A1708 no power stuck on 5V

    I had the exact same problem with 3.3v only being 2v and it was the U7000 , ISL9240 and in the end it couldn't repaired as the parts not available.

 

 

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