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    toshiba u400

    I have a toshiba u400 that turns on for 1 sec and immediately off . When you connect the power adapter, battery seem to charge (charge light is on) . I took apart everything and found that if I remove the processor laptop power stays on . Tried different processor , problem the same . It doesn't have any nec/tokin caps on cpu socket . Any ideas ?

    #2
    Re: toshiba u400

    check cpu vcore power area...

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      #3
      Re: toshiba u400

      Originally posted by pctek View Post
      I have a toshiba u400 that turns on for 1 sec and immediately off . When you connect the power adapter, battery seem to charge (charge light is on) . I took apart everything and found that if I remove the processor laptop power stays on . Tried different processor , problem the same . It doesn't have any nec/tokin caps on cpu socket . Any ideas ?
      Remove CPU and measure resistance to CPU coils if resistance is low there is short circuit on motherboard.

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        #4
        Re: toshiba u400

        Found 2 shorted capacitors . Removed both but when tested out of board seemed ok .

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          #5
          Re: toshiba u400

          Originally posted by pctek View Post
          Found 2 shorted capacitors . Removed both but when tested out of board seemed ok .
          Have you got the schematic for this Toshiba?
          If you have an external power supply, (regulated and short-circuit capable) you can inject a low voltage to the positive connection of capacitors, (negative to ground) and see if there is something that gets hot. (another cap.)
          The voltage should be as low as possible, and increment in small-steps, if required.
          Good luck.

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            #6
            Re: toshiba u400

            Originally posted by Francisco.s View Post
            Have you got the schematic for this Toshiba?
            If you have an external power supply, (regulated and short-circuit capable) you can inject a low voltage to the positive connection of capacitors, (negative to ground) and see if there is something that gets hot. (another cap.)
            The voltage should be as low as possible, and increment in small-steps, if required.
            Good luck.
            Also limit current to 200ma and increase slowly .

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              #7
              Re: toshiba u400

              What kind of power supply can be used for this and exactly how low should the voltage be?

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