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This is a strange question and I am absolutely not sure if this is the right place to ask. However, I'll give it a try:

I have a Asus Zenbook notebook. The notebook only has a HDMI/Display port input. When I want to connect it to an older projecter, I use a VGA to Display port adapter. However, there is one projecter in our university, where I experience random noise on top of mouse movements when using the touchpad. Let me explain this:

I place my notebook on a table, connect it via VGA to DP adapter to a VGA cable that is connected to the projecter. As soon, as I plug in the adapter to my notebook, when using my touchpad, the movements experience random jumps and clicks and it makes my notebook unusable.

However, the moment I touch the body of my notebook, this does not happen any longer. Also picking up my notebook and using the mouse pad while holding the notebook in my hands does work.

The problem only occurs with this specific projecter. Different VGA cables and a different adapter did not change anything.

So my (uneducated) guess is: This has something to do with the notebook not being grounded. I also tried to plug the power adapter in, but this did not help.

My question: Is my guess correct? If so, is there an easy hack to get rid of this problem?

Also, since I am really not sure if this is the right place to ask, any references are very much appreciated.

Thank you very much.

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  • Touch pointer shows erratic behavior when you use a noisy(electrically) power source. One of the power supplies (most probably beamer's) is faulty.
    – AEonAX
    Apr 27, 2015 at 7:51
  • Is there something I can do to fix this? There are other notebooks that work fine when connected to the beamer.
    – Thomas
    Apr 27, 2015 at 7:55
  • You said holding the Laptop in hand does work. So basically you are not grounding since you must be wearing shoes. How about placing the laptop on electrically insulated material and using it such that you don't ground it yourself.
    – AEonAX
    Apr 27, 2015 at 7:59
  • After a second reading of your question it seems you ground the device when you touch the body. Externally grounding might be hazardous to the device.
    – AEonAX
    Apr 27, 2015 at 8:02

1 Answer 1

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This sounds very much like some (tiny) static current would be on the VGA cable's shielding. If you touch the notebook (or hold it), you essentially ground it, removing that current, which screws with the touch pad.

You should report the issue to someoe responsible with your university's tech stuff. The issue is just minor right now, but might cause serious harm or (hardware) damage in case there's another fault in addition (like some PC with broken isolation on its own).

As a temporary workaround, just get some wire and connect a metallic portion of your notebook with some grounded part of the building (radiator, sink, ground pin in a socket). Just be careful not to cause any short circuits. Even connecting your notebook's charger might be enough. Note that this is really just short-term and shouldn't be a permanent fix. You might damage your hardware (beamer or PC) that way.

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