Wavy lines on external monitor when using SP hub

Discussion in 'Microsoft Surface Pro' started by HDRider, Feb 17, 2018.

  1. HDRider

    HDRider New Member

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    When using a Dell 1794FPV monitor external to my Surface Pro, it works fine if connected directly to the computer but, when connected through the SP hub, the monitor has a slight, low frequency wave to it that increases & decreases in frequency. Tried setting the monitor to 75Hz (from 60Hz) and noticed a slight improvement but the wave is still there. Any suggestions?
     
  2. jnjroach

    jnjroach Administrator Staff Member

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    What kind of adapter and/or cable are using to connect?
     
  3. HDRider

    HDRider New Member

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    Using the adapter that was supplied by Microsoft (VGA to USB-C) and a standard VGA cable....tired several different cables, all with the exact same results. If it is plugged directly into the port on the Surface Pro, no wave to the image. But if I go through the hub, waves.....would think that this installation comparison would eliminate the possibility of the problem being the cable but perhaps the hub is actually altering the frequency somehow.?.

    Also, have checked the grounding (electrician by trade) on the monitor, and everything is ok there....even tried using a "no ground/two prong adapter" at the suggestion of another with no luck. ***BUT, the power cable for the hub itself does not have a ground pin. so neither the hub nor the computer that is powered through it are grounded.
     
  4. HDRider

    HDRider New Member

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    Correction on the adapter...it is Mini DP to VGA
     
  5. jnjroach

    jnjroach Administrator Staff Member

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    Yeah, that is an ancient monitor...I have little luck with VGA monitors on the dock. DVI, HDMI and DP all work well but VGA has been less then optimal.
     

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