Signs of electromagnetic interference?

Question

I recently picked up a 22 inch Samsung LCD monitor, it was used but it worked perfectly when I got it. Now that its in my office, I've noticed that there are horizontal lines of "static" moving across the screen. I've been told that this is a sign of interference coming from other devices, but my computer tower is at least 1.5 feet away from the monitor, and the only other device that could be causing it is the electric fan next to me. Somehow I doubt that.

Is there any other way to tell where this interference is coming from?

Solution

Ok, so I tried out all the suggestions, moving it to another power outlet, trying it on another computer, and removing the fan, but none of them seemed to work. I then switched out the VGA cable for another one I had lying around, and boom, the problem is fixed. No more static/lines on the monitor, and everything is crystal clear.

I don't know what exactly caused the problem, but I'm guessing that the original cable was damaged (although I can't see any traces of physical damage), or that it lacks shielding. I do note that the original cable is significantly thinner than the new one that I put in. Any comments on that?

Comments

[Enrico Tuvera Jr]

I've unplugged the fan and moved it, and the problem still persists. I'm thinking now that it might be the VGA cable, but it looks intact. I'll see if I can't dig up another cable and try it out.

[Keltari]

hook the lcd up to another computer to see if the problem persists.

[vonbrand]

Re @Keltari's comment, or move it elsewhere. Try in another room, at home. See if turning off other electric appliances/ligts does make a difference. I don't think it is a cable problem, a line means some kind of periodic interference with a decent frequency (frame refresh or thereabouts).

[Rajesh Sinha]

Bob please go through this superuser.com/help/how-to-answer and better re-write the answer which reflects a question rather then answer.