Problem with laptop: not power on

Discussion in 'General Electronics Chat' started by gldiana, May 19, 2011.

  1. gldiana

    Thread Starter New Member

    May 19, 2011
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    0
    I have a Toshiba Portege r500. When I plug it to power supply, the solid power led swithces on, and if battery is connected starts to be charged regurarly. But when I push power on button, the power led swithces off for a while, and after switches on again, but laptop does not boot-up.

    Rarely the problem disappear, and the laptop boots-up.

    Seems that there's a short on motherboard that stops power supply circuitry when power on button is pushed, that sometimes disappears.. I've tried to unplug all devices (wifi card, ram socket, auxiliary boards, dvd, hd) but problem stays there...

    Any suggestions on how to find the problem??
     
  2. tom66

    Senior Member

    May 9, 2009
    2,613
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    Does it work from AC without the battery?
     
  3. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    If someone dropped the laptop, or hit the power button to hard, it may have cracked a solder joint on the power button.

    The power button is not like a wall switch. It routes power to a few sub-circuits to initiate boot-up.

    The charger changes current, the power management circuit checks temperatures and switches fans, the LEDs change colors, and the main power MOSFET is switched ON.

    If any of these are not communicated with and returned as 'OK' the main power MOSFET does not close.

    Some models of computers will blink out a code on the indicator LED to let you know where the problem is.

    If there is a wiring connector near the switch on the mainboard, make sure it is not loose.

    Check to see if any spilled liquids may have gotten inside.
     
  4. gldiana

    Thread Starter New Member

    May 19, 2011
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    0
    Hi all, thanks a lot for your reply. I can add some infos. Yes, I've tried to boot-up without main battery, and also only with main battery (fully charged and without AC plug), but problem stays there.
    And the laptop has taken a couple of serious hits (also a car accident). On last hit the plastic panel behind LCD has been broken, but laptop did not show any other problem. So I've bought a spare, and to install it removing the broken one, I had to remove and re-install the mainboard. and from that moment in time i got the problem described above.
    I will try today to re-sold the power button and the main power wiring connector, and let you know!
     
  5. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    Its worth a try.
     
  6. gldiana

    Thread Starter New Member

    May 19, 2011
    3
    0
    Hi! Tried to re-sold power button, no success... Any other suggestions (apart to replace the MB!)?
     
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