Bridging fuses on Carbon X1 Gen2 for no power to screen?

Discussion in 'Lenovo' started by zeros000, Feb 14, 2017.

  1. zeros000

    zeros000 Newbie

    Reputations:
    0
    Messages:
    2
    Likes Received:
    0
    Trophy Points:
    5
    Hi I have a Lenovo Carbon X1 Gen2 with i7-4600U with the screen not working after replacement. Also replaced the display cable.
    I found two fuses that show 1 on the multi-meter but a different number if checked with ground. Don't know which I'd have to "fix" to make the screen work again. One is under the bios battery and the other in the corner next to where the cpu fan and one of the cables to the screen goes (sounds obvious eh? well I don't want to bridge one and break something more)
    The one near fan is F33 5A/32V, the one next to RTC battery is F3 3A/32V. Upon further inspection the one near the battery is bellow the display cable and the one near the fan is the one near the other cable that goes to the screen.
    Looking on the forums I saw people circled most of the time the big fuses, there's only one big F2 7A/24V which gives 001 like all of the other working fuses, this fuse seems to be for the power plug though.
    Images:
    http://i.imgur.com/7RWo1PO.jpg
    http://i.imgur.com/eTzBVKL.jpg
    http://i.imgur.com/XluiviJ.jpg
    Close ups to the 2 fuses:
    http://i.imgur.com/mUhonN9.jpg
    http://i.imgur.com/fVVofaQ.jpg

    Thanks.
     
  2. zomi

    zomi Notebook Enthusiast

    Reputations:
    0
    Messages:
    13
    Likes Received:
    0
    Trophy Points:
    5
    You need to test across the fuse
    if they show 1 they are ok
    There will be more fuses on the board you will have to find and test them
    till you get to the one that is blown,
    You need to find a replacement fuse once you find which is blown
    bridging it means should something similar occur again it will take out more than the fuse
     
  3. Lucjan

    Lucjan Newbie

    Reputations:
    0
    Messages:
    1
    Likes Received:
    0
    Trophy Points:
    5
    I have exectly the same problem. To my understanding the fuse is OK when the resistance is nearly zero. If it shows 1 the fuse should be not working. For me the fuse 7 seems not to work. But it is all so small that I had trouble creating an shortcut so I did not really managed it. My Lenovo is still working properly when I plug in a external monitor. But the light of the display on my laptop display is very very dim. It is the backlight that is not working. I suppose it is fuse 7 that us blown but as I said really difficult to replace
     
  4. t456

    t456 1977-09-05, 12:56:00 UTC Moderator

    Reputations:
    1,054
    Messages:
    2,095
    Likes Received:
    1,283
    Trophy Points:
    181
    A working fuse has zero (really close-to-zero) resistance to the load passing through. Only when it has been triggered will it show 1, meaning infinite resistance.
    Those are all way too large to have been used as display fuses; these should be at most ~1A/24-32V, matching the lower maximum rating of the panel. More probable that the fuse that has been triggered is on the panel itself. Ideally, there should be two of them; one for the backlight (heavy duty) and a smaller one for the lcd/control:

    [​IMG]

    Use a soldering iron and drown it in solder, bridging both ends. But yes; zomi is correct in that there is some risk involved if the cause was a hardware defect somewhere further down the circuit and not a once-off spike in the power grid.
     

Share This Page