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Toshiba U920T dead, water damage

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    #1

    Toshiba U920T dead, water damage

    Hi everyone,

    I have a Toshiba U920T laptop that suffered a lot of water damage and is now dead.

    There was lots of corrosion on the motherboard, specifically around the power input components but generally all over too.

    So I have been playing around with it, I put the motherboard in some boiling water and scrubbed off all the corrosion I could see, then washed with some IPA, then put it in the over at 250C for a few minutes. Didn't work.

    So I have been trying to test how far the power goes with a voltmeter, and straight away noticed it doesn't pass the first component. I have no idea what this component is, never seen one like it, it didn't have any markings on it or the motherboard. It seemed to have a plastic cap on the top that I popped off and saw it was some kind of coil, it has 4 pins, the 0V and 19V go in, and the 0V and 19V come out. I could see the copper wire coming out of the 19V was no longer connected, so I got a tiny bit of wire and connected the 19V in to a component on the other side of this coil.

    To my absolute shock the small LED came on to say it was battery was charing, so I turned the laptop on and it actually fired up, I flipped it over to check the screen and there was a message about the RTC battery being low (as it was not plugged in).

    The laptop was on for about 10 seconds before I unplugged it to put the SSD in and see if I can get it to boot to Windows. I have since not been able to get any life out of the machine, although I am sure i saw one LED flicker very briefly.

    Does anyone know what this small component is that is broken? I assumed it would just be some kind of filter, and therefore bypassing it for a few seconds would not do much harm.

    I have checked a few more voltages on the board, I am picking up a few 2V's, 3V's and 6V's here and there. There is nothing on the 4 p-channel mosfets though.

    Thanks!
    Graham
    Attached Files
    Last edited by grahamw01; 09-27-2014, 10:10 AM.
    Tags: None
    #2
    Re: Toshiba U920T dead, water damage

    clean with ipa and please take down that ugly wire. omg my eyes became red!
    do a vertical picture with good light so we can see the trace.
    you got there diode capacitor resistor and if you take the hat from the coil it will NOT work.
    Just cook it! It's already broken.

    Comment

      #3
      Re: Toshiba U920T dead, water damage

      Originally posted by dj_ricoh View Post
      clean with ipa and please take down that ugly wire. omg my eyes became red!
      do a vertical picture with good light so we can see the trace.
      you got there diode capacitor resistor and if you take the hat from the coil it will NOT work.
      Hi again!

      as requested

      thanks!
      Attached Files

      Comment

        #4
        Re: Toshiba U920T dead, water damage

        a few more..
        Attached Files

        Comment

          #5
          Re: Toshiba U920T dead, water damage

          I cleaned the whole board with IPA again and put that wire back in (sorry). When I plug the AC in the AC LED comes on! I thought it was going to turn on again, but it doesn't. The AC LED stays on but it is not as bright as it should be, also it doesn't go orange to say charging like before.

          Something happened though after washing it with alcohol..

          Comment

            #6
            Re: Toshiba U920T dead, water damage

            I was just playing plugging the AC adapter in and out and the laptop turned on completely 1 more time! I unplugged it and tried a few more times again, nothing!

            Comment

              #7
              Re: Toshiba U920T dead, water damage

              You have an intermittent connection caused by corrosion eating away one or more traces. Give it a real good look and you should be able to find it.
              Originally posted by PeteS in CA
              Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
              A working TV? How boring!

              Comment

                #8
                Re: Toshiba U920T dead, water damage

                Originally posted by Th3_uN1Qu3 View Post
                You have an intermittent connection caused by corrosion eating away one or more traces. Give it a real good look and you should be able to find it.
                Thanks, if it is just trace damage, what about the coil I am bypassing? I tried to glue the hat back together but superglued it to my desk instead and it shattered when I tried to break it off, I know there are lots of words you can call me!

                Comment

                  #9
                  Re: Toshiba U920T dead, water damage

                  That sounds like a problematic fet.

                  Comment

                    #10
                    Re: Toshiba U920T dead, water damage

                    I left everything unplugged overnight then this morning connected it up and it turned on first time, was just on for about 5 minutes before it killed itself. Now I can't get any lights to come on again.

                    Comment

                      #11
                      Re: Toshiba U920T dead, water damage

                      there is a QFN with 24 pads, photographed above, that looks like some of the joints are quite corroded. There are no markings on or around the chip so not sure what it is. What would be the best way to fix the joints? I planned to cover it in flux paste and reflow with a heat gun and fine tip, would this work?

                      thanks

                      Comment

                        #12
                        Re: Toshiba U920T dead, water damage

                        Clean it very good first, then apply flux and reflow, then solder the pins.
                        Originally posted by PeteS in CA
                        Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                        A working TV? How boring!

                        Comment

                          #13
                          Re: Toshiba U920T dead, water damage

                          Originally posted by Th3_uN1Qu3 View Post
                          Clean it very good first, then apply flux and reflow, then solder the pins.
                          Thank you i'll give it a go, do you know the purpose of that coil and if I can do more damage by bypassing it?

                          Comment

                            #14
                            Re: Toshiba U920T dead, water damage

                            i think for over voltage!

                            bypass it!
                            Just cook it! It's already broken.

                            Comment

                              #15
                              Re: Toshiba U920T dead, water damage

                              I did my best to clean and resolder the bad joints I could see but still same story. Could this be bad fets as atsio suggested? Could a bad fet sometimes work like this?

                              Comment

                                #16
                                Re: Toshiba U920T dead, water damage

                                had a bit of luck with it I think, just resoldering some bad looking pins and now it seems to actually work, I've had the laptop on and running almost perfectly for the past few hours. This is also just with a solder link across the dead inductor.

                                My issue now seems to be with charging. If I plug the battery and AC in the charging light comes on, if I unplug the battery it goes off, so it is registering a battery. However windows has just stated "3% available (plugged in, charging)" and does not budge from 3%. If I unplug the AC the laptop just turns straight off.

                                Any ideas for this??
                                Thanks!

                                Comment

                                  #17
                                  Re: Toshiba U920T dead, water damage

                                  one dead dud battery for the recycle

                                  Comment

                                    #18
                                    Re: Toshiba U920T dead, water damage

                                    Hi trebo, thanks for the comment, I think the battery is fine though as it was working perfectly before the water damage. I think something is wrong with the charging circuit. Also after a few hours of being on the charging light goes off and windows states no battery detected, but after unplugging and plugging back in it returns to 3% plugged in, charging.

                                    thanks

                                    Comment

                                      #19
                                      Re: Toshiba U920T dead, water damage

                                      A few things I hope someone will be able to understand,

                                      With the AC in and no battery, and no charging LED, the battery V+ is 1.5V. With the battery in and charging LED on the V+ is roughly 8V. The battery itself is at 8V and has been like this for a few days regardless of how long it has been plugged in.

                                      Just now I checked the amps across the battery and it was roughly 4A. The battery itself says 11.1V, 3280mAh. Doing this must have shorted the battery temporarily because the voltage has dropped to 7V. So I plugged it in to charge and the voltage is increasing 0.01V every few seconds.

                                      To me it looks like the laptop is only giving the battery 8V max which I guess equates to about 3% like it always shows.

                                      Comment

                                        #20
                                        Re: Toshiba U920T dead, water damage

                                        can anyone please offer a probable reason why the battery is only getting 8V when the charging circuit is on?

                                        thanks!

                                        Comment

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