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LA-7092p (packard bell P5WS6), some advice before wasting time

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    LA-7092p (packard bell P5WS6), some advice before wasting time

    hello guys,

    need some advice
    have to repair a PB laptop, with la-7092p motherboard
    at start : no led, no power, totaly dead
    19v not present after 1st mosfet, short to ground. found upper mosfet on +1.5V that was short (between 19v and 1.5V), lower mosfet between +1.5 and ground is ok

    RAMS are dead too i think : after changed mosfet, short remove without rams and reappears when rams plug in. if i put a new ram, no short at all.

    if i remove rams : i have 19v , 3.3v , 5v but no +1.5v and no 0.75v (that's normal i think cause it cames from +1.5V)
    the regulator that generates +1.5V have 3.3V and senseon present, but no outpout voltage (3 lines of 1.5V)

    so i think Rams AND maybe CPU dead no ?
    i have ordered some regulators to test, but this could be a waste of time.

    what do you think guys ?
    thanx again !

    #2
    Re: LA-7092p (packard bell P5WS6), some advice before wasting time

    CPU could be dead as a result of the high-side MOSFET shorting and sending 19V down the line, but no way to confirm it (it's not fully shorted to ground so that's good at least).
    Usually when replacing a shorted MOSFET in a buck converter circuit it is a good idea to replace the MOSFET driver as well. (you never know if the MOSFET driver caused the MOSFET to die, or if the MOSFET damaged the MOSFET driver while dying)
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

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      #3
      Re: LA-7092p (packard bell P5WS6), some advice before wasting time

      hello
      finally change the mosfet and the driver.
      after change the driver, the mosfet dies ! not understand why.
      when mosfet is in place : 19V rail is short to ground, when mosfet is out, no short anymore on G,S and D. and mosfet short D-S
      i give up this one. to much time. but if someone understand why this fet dies i'll glad to know.

      thx guys

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        #4
        Re: LA-7092p (packard bell P5WS6), some advice before wasting time

        Was the mosfet driver new??

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          #5
          Re: LA-7092p (packard bell P5WS6), some advice before wasting time

          hello,

          yes, new from aliexpress but new.

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