My screen keeps shaking no matter what I do.

[Shauna3213]

A few months ago, my screen began shaking slightly, and has been worsening every since, to the point that it hurts my eyes now to use the computer. Here are the facts:

* My computer is an iMac about five years old. Other than the screen, it runs pretty smoothly.

* The screen began to shake when I had the computer in my dorm room at school. It continues to shake now that I have it at home.

* I read that screen-shaking is sometimes caused by magnetic fields. I've tried turning off electrical devices like fans and lamps, and removing them from the room, but I'm not exactly sure what things have magnetic fields, though, and how big those fields are, so I could be doing it wrong. I also tried putting a metal cookie sheet around the computer to protect it, but I only have one sheet and it didn't seem to work no matter where I put it.

* A couple of times over the past few months the computer screen has suddenly and completely stopped shaking. This lasts for about an hour or so. Then, rapidly, the screen begins shaking again, until it reaches the same, eye-wrenching level it was at before.

Anyway, I hope you can help. I'm happy to try any suggestions, short of "Buy a new computer."

[kc0arf]

Hello,

I am inclined to believe that this is something particular to your iMac. Moving it around, or putting it in the center of a room should have eliminated a lot of the fields in the walls.

Incidentially, moving electrical currents cause magnetic fields. They are 90 degrees out of phase with the electrical current, meaning if the electricity is travelling up a wall, the magnetic field is travelling 90 degrees out of the wall, such as if you were to put a nail into the wall to hang your coat on. Because current is always flowing (alternating current changes direction 60 times a second, 60 Hz) the magnetic field is also pulsing back and forth, thus the "wobble" you see on a monitor.

To test for magnetic fields, you can use a compass. You can also use an AM radio, tuned to "static" and hover that around a device, and listen to the warbling and distortion the fields make.

Christian

[Shauna3213]

To test for magnetic fields, you can use a compass. You can also use an AM radio, tuned to "static" and hover that around a device, and listen to the warbling and distortion the fields make.

I couldn't find a compass, but when I went around the room with an AM radio I discovered the disturbance was coming from my digital broadband box. Decreasing proximity to the box had no effect on the computer, but unplugging it did. My screen is now shake-free! Thank you for such a prompt, helpful, and even educational reply!