Main Repair Questions Toshiba Qosmio mb issue

Viewing 6 posts - 1 through 6 (of 6 total)
  • Author
    Posts
  • #10564
    Joe. Palmers
    Participant
      • Topics 1
      • Replies 2
      • Total 3
      • New Member

      Hello everyone!
      Have a Toshiba qosmio that charge and turns on, but with no display and no cpu fan spinning. When powered on, cpu and gpu gets hot. Seems a missing voltage rail or a short somewhere.
      Since its poweing on with the power switch, then 3.3v is available.
      Any starting point to proceed with the diagnostic? ( checking coils, checking for short etc..).
      Thanks in advance

      #10589
      NorthridgeFix
      Keymaster
        • Topics 0
        • Replies 67
        • Total 67
        • Admin

        It could be a lot of things. On some laptops fans do not spin until temperature reaches a certain degree. You need to manually probe for a short by measuring Capacitors and Mosfets in Diode mode. A thermal camera will help visualize thermal properties as the board is turning on and that can sometimes help narrow things down.

        #10605
        Joe. Palmers
        Participant
          • Topics 1
          • Replies 2
          • Total 3
          • New Member

          Hey !
          Thanks for your kind reply.
          The cpu fan isn’t turning on at all, motherboard will shut down later when cpu and gpu gets hot.
          When turned on, all the coils have voltages.. I will dig in more, testing mosfets and capacitors in diode mode and see what i can find.
          Unfortunately, I don’t have a thermal camera. This should be on my purchase list later on.
          Thanks !

          #10661
          NorthFix Tz
          Participant
            • Topics 0
            • Replies 1
            • Total 1
            • New Member

            Another thing you can check if you Mb has GPU,,GPU failure can cause no display ,check mosfet around CPu and around GPu.Thanks

            #10732
            rtstorm
            Participant
              • Topics 1
              • Replies 4
              • Total 5
              • New Member

              I think that there i definitely some kingd of short to gnd, the sad thing is that there is a good chance that you have a dead GPU. You need to use thermal cam or rosin vapour or alcohol to check

              • This reply was modified 2 months ago by rtstorm.
              #10857
              Joe. Palmers
              Participant
                • Topics 1
                • Replies 2
                • Total 3
                • New Member

                Hello! Thanks for your kind replies.
                Does this short cause the cpu fan not to spin? When turned on, cpu and onboard gpu gets hot. Will check for short around cpu and gpu.
                On YouTube , i saw a video, same case but with an hp mb, turned out a shorted cap causing the issue. It was detected by voltage injection at the shorted area.
                Thanks for your time !

              Viewing 6 posts - 1 through 6 (of 6 total)
              • You must be logged in to reply to this topic.