Wavy, Flickering, or Jittery Video on a VGA Connection Connected to a Laptop

You can experience wavy or flickering or jittery video on a Video Graphics Array (VGA) Connection. Where a monitor or a projector is connected to a laptop powered through an external AC adapter. A VGA connection uses an analog signal to transmit data from the laptop to the display. This is considered as a legacy type connection and is more susceptible to interference in the data transmission. (Newer digital connections like High-Definition Media-Interface (HDMI) and DisplayPort (DP) do not have this issue.)

Testing for the existence of a ground loop is a likely cause of electromagnetic interference (EMI). This EMI can be interfering with the video signal to your external device.

This section is not applicable to this article.

Use the following tests to determine the issue:

• Ensure that you are using the latest revision of the AC adapter that is available for your laptop
• Test with both a three prong AC adapter and a two prong AC adapter (if possible)
• Test with a grounded AC plug adapter 3 prong to two prongs (if possible)
• Test with a double or triple shielded VGA video cable (if possible) Search for a shielded VGA cable on Dell.com or Google.com to bring up several examples
• Test with a digital video connection (if possible) For example: Digital Visual Interface (DVI), DP, or HDMI)
• Test with a ground loop isolator  (if possible)

Useful Links

Ground loop problems and how to get rid of them:

• https://www.epanorama.net/documents/groundloop/ 

What is the problem in grounding systems used in buildings?

• https://www.epanorama.net/documents/groundloop/electrical_wiring.html