Dell U2518 no picture

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  • timeless
    New Member
    • Apr 2024
    • 3
    • Netherlands
    #1

    Dell U2518 no picture

    Hi,

    I've been troubleshooting a Dell U2518 that produces no picture yet the backlight is turned on, the PSU produces 19v, It is detected over HDM and its firmware could be upgraded over USB. So to me the controller board and PSU seems (somewhat) functional.

    There is however a ticking noise from the T-Con board to the left side of the RT6811 chip when power on (not when off). Also the RT6811 chip gets quite hot (cannot be touched for long) otherwise there is no physical sign of damage and everything around the board is neatly covered with plastics and does not show any sign being shorted. The VDD of the T-Con board measures 10v, as I don't have the schematics I cannot say for sure if this is normal but the other test pads with a voltage printed next to them like VCC_3.3, VCC_1.2 and such measure correctly. As the T-Con board is divided into 2 separate boards connected with a flex cable, I tried to disconnect the flex cable and hopefully identify that part of the screen to be at fault. But this did not help and as the T-Con board is bonded to the screen I have no way unplugging the other part.

    To me it seems very likely to be a panel problem, but I'm curious if there might be other suggestions I could try.
    Thanks in advance.
    2 Photos
    Tags: None
    • CapLeaker
      Leaking Member
      • Dec 2014
      • 7973
      • Canada
      #2
      Probe the LVDS signals with an 100MHZ or better oscilloscope and change the menu OSD all the time, or give some input like a YouTube vid. If the signals change, it's the tcon. Pretty much this is a lost cause, because of the welded tab bonds. A shorted panel can be unshorted, but I don’t recommend doing this, unless you know exactly what you are doing.
      Last edited by CapLeaker; 04-14-2024, 10:05 AM.

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