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Short somewhere Toshiba C660-18C

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    #1

    Short somewhere Toshiba C660-18C

    Hello there guys, it's my second post on the forum

    Well I have a problem on the Toshiba C660-18C with ref PWWHA LA-7202P Rev 1.0.

    The problem is on the capacitors PC414 and PC415, they have blown away it's guts, so i suppose there's a short in some place.
    There is also no video or some light indicator.

    I haven't tried to power the board again as it can blow some more components.

    Could you guys help getting the problem solved or help me troubleshooting it?

    Thanks you all!
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    #2
    Re: Short somewhere Toshiba C660-18C

    Why would a short in some place blow away caps in another? Overvoltage can do that to caps (bad powersupply maybe). Maybe too much heat. Remove the caps and clean the pads. Then measure resistance on their pads. Then measure resistance from PL402 to gnd. Inspect full board visually, because the caps where in B+ rail, this goes everywhere.If all seem ok, then replace the caps and try to power on and hope for the best.

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      #3
      Re: Short somewhere Toshiba C660-18C

      So after removing the Caps (PC414,PC415,PC413) i've measured their pads for continuity and theres 0 resistance / continuity.

      I've measured the PL402 pads (both of them) and both have continuity to GND.

      Can't really understand what the problem is.
      Should i replace the caps and try to power it?
      There's no visual damage in any component.

      Thanks

      Comment

        #4
        Re: Short somewhere Toshiba C660-18C

        Originally posted by khaahk View Post
        Why would a short in some place blow away caps in another? Overvoltage can do that to caps (bad powersupply maybe). Maybe too much heat. Remove the caps and clean the pads. Then measure resistance on their pads. Then measure resistance from PL402 to gnd. Inspect full board visually, because the caps where in B+ rail, this goes everywhere.If all seem ok, then replace the caps and try to power on and hope for the best.
        Well, one thoery could be that there was an overvoltage, the caps blew, then the full overvoltage shorted out some semiconductor or other device...
        Muh-soggy-knee

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          #5
          Re: Short somewhere Toshiba C660-18C

          As long as you have 0 resistance on B+ rail, there is no point in powering it up. If you have lab power supply then you can try to isolate the shorted component.
          Try to remove PL401 and see if B+ has still 0 ohms to GND.
          If not then you can concentrate on 1.05V rail to find the short. Else there is full board to look at.

          "I've measured the PL402 pads (both of them) and both have continuity to GND."
          How many ohms?

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            #6
            Re: Short somewhere Toshiba C660-18C

            Hello,
            I do have a lab power supply, she can do 15v 2A.

            On PL402
            From one side I can't get exact Ohm measuring as it keeps giving 14,7 and sometimes 3 Ohm to GND on power source in at the motherboard.
            From the other I get 14,7 Ohm to GND on power source in at the motherboard.

            I'm still checking the caps pads as one of them has infinite Ohm...
            It's really hard to trace the problem without isolating it.

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              #7
              Re: Short somewhere Toshiba C660-18C

              Did you remove PL402 when measuring resistance? 14ohm might not be a short.

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                #8
                Re: Short somewhere Toshiba C660-18C

                I haven't removed PL402

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                  #9
                  Re: Short somewhere Toshiba C660-18C

                  Remove it when doing measuring, because coil resistance is almost 0 ohms for DC.

                  Comment

                    #10
                    Re: Short somewhere Toshiba C660-18C

                    After so much time spent on the board trying to diagnose the problem, the costumer said he didn't want to repair it and rather buy a new laptop, maybe I negotiate with him to get it for a reasonable price for spare parts.

                    Thanks for all the help provided and especially for khaahk

                    Comment

                      #11
                      Re: Short somewhere Toshiba C660-18C

                      guy....do you have a dumb files for that unit i mean bios file

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