Author Topic: Odd monitor behavior that I cannot solve (Read 1181 times)

Karnak · « **on:** September 08, 2004, 01:07:10 PM »

I just moved a couple of weeks ago. I am now in a tiny basement apartment with very limited options for arranging furniture.

The problem I am having is that the monitor's image shakes horizontally. At 640 by 480 it is a slow shake, myabe one occilation per quarter second, that varies the position of the picture by a couple of milimeters. At higher resolution it vibrates at a very high rate, but seems to vary the position by less than half a milimeter. Either issue makes the computer nigh unusable. I did find that running the screen at 60Hz. While this stabalizes the picture it is not an acceptable solution as it will quickly result in a headache.

I thought that the monitor was going so I bought a used 21" Sony G500. This monitor does the same thing now that I have it and have it set up.

After I had ordered the new monitor, but before it had arrived, I noticed a couple of things that lead me to believe that the problem is environmental and not hardware related.

1) The problem only appears after about 18:30 and disappears at about 23:30.
2) There is a large power cable running on just the other side of the sheetrock from the monitor. Maybe about 10"-14" away from the monitor.
3) Both monitors exhibit a discoloration in the picture in the upper left corner.

I can't think of any way that the video card could be doing this so I have not tried to change that part. I have rearranged all the cables to minimize the monitor cable's contact with other cables and I tried a plug further away. None of this helped. Routing the power through a UPS also had no effect.

I am stumped and can no longer afford to throw money at the problem.

Any ideas?

JB73 · « **Reply #1 on:** September 08, 2004, 01:09:02 PM »

that sure sounds like a magnetic field too close to the moniter.

Karnak · « **Reply #2 on:** September 08, 2004, 01:29:00 PM »

That is what I am lean towards. The question is, how do I solve it?

I can, with a lot of work, move the monitor about a foot and a half further way, but at the expense of having the computer where the monitor is now.

gunnss · « **Reply #3 on:** September 08, 2004, 01:40:57 PM »

JB73 is right.

You need to put a EM shield between your monitor and the cable. Get a piece if sheet steel 30" by 30" Bolt or solder or weld a metal to metal connection to the plate with a 12 Ga. or thicker copper wire. Run the copper wire to ground. If you use the electrical ground of the building, make shure that it is on a diffrent circuit than the one that feeds your monitor. the better your connection to ground the better the protection will be. Ground means an "electrical ground" not hooking the wire to the floor. If you don't understand electrical wiring get competent help. Not trying to talk down but an incorrect installation won't help, and if hooked to the hot side of an outlet could shock you.

what this does is gives the electro magnetic waves an easy path to Ground allowing your monitor to be unaffected by them.

Good Luck,
Gunns

llama · « **Reply #4 on:** September 08, 2004, 03:55:41 PM »

Yes, it is a magnetism problem. Something nearby that uses a fair amount of electricity is creating a magnetic field and it is affecting your monitor. You can get a similar effect by putting a TV or second monitor close to the first, using unshielded speakers close to the monitor, etc. You can ALSO get a similar effect if the something using a lot of power is on the same circuit as your monitor. I have seen this happen.

For solving it, I have never had luck in making a shield from sheet metal, but I hear it can help.

Usually, I try the following:

1. Get a LONG extension cord. Plug the monitor into another circuit in the house and see what happens.

2. ROTATE the monitor. The effect is greatest when the monitor's field and the interfering field are in phase and oriented in the same direction. See what happens.

3. Move the monitor. This is probably what you will have to do. Just a few feet can make a lot of difference. Experiment around with monitor placement.

4. Try different resolutions and referesh rates. Some make the jiggling more visible, and some less visible.

5. Buy an LCD display. They don't use a magnetic field to point electrons to display an image.

6. Get a UPS (battery backup device) and plug the monitor into it. These have electrical filtering that can help at times.

Only #3 and 6 are GUARANTEED to work, but some of all of these tips may help.

Good luck.

-Llama

Karnak · « **Reply #5 on:** September 08, 2004, 05:02:37 PM »

Thanks for the suggestions.

Llama,

#6 most assuredly did not work. It was the first thing I tried.

MOSQ · « **Reply #6 on:** September 08, 2004, 06:40:45 PM »

7) Go tell the guy with the Marijuana grow in the attic to knock it off or you're calling the police.

bloom25 · « **Reply #7 on:** September 08, 2004, 06:43:14 PM »

I'd agree that this is likely interference caused by proximity to a cable carrying a large varying electric current. (You could confirm this by rotating the monitor and observing the effect.) If this is the case all you really need to do is move the montor. Electric field strength is inversely proportional to the square of the distance. Thus if you double the distance between the source of the interference and the monitor, the electric field strength will be quartered.

Roscoroo · « **Reply #8 on:** September 08, 2004, 07:18:53 PM »

these guys are probely right .. but I did have a similar problem once with a certian set of gforce drivers .

i had two pc"s right next to each other and only my pc had the video shakes ... you havent done a driver change lately have you ?

llama · « **Reply #9 on:** September 08, 2004, 09:29:00 PM »

Quote

Originally posted by Roscoroo

i had two pc"s right next to each other and only my pc had the video shakes ... you havent done a driver change lately have you ?

One monitor was generating a magnetic field that was affectng the other. Different monitors are more likely to have this happen than some other monitors.

The test is to turn off the "stable" monitor and see if the "shakey" monitor suddenly clears up.

I myself have a small 9" TV about a foot from my nice 20" Flat-CRT monitor. When both were side by side, turning on the TV gave the monitor a severe case of the Wiggles. Turn off the TV and the monitor was back to normal.

My new desk is a "corner desk" so the monitor is now a foot away from the TV, but the screens are at a 45 degree angle relative to each other. Now the Wiggles are almost gone, but barely noticable if you look for it.

If I move the TV just 1 more foot away, the Wiggles disappear completely.

Magnetism is indeed amazing...

-Llama

qts · « **Reply #10 on:** September 17, 2004, 03:08:47 AM »

Gunss is spot on. Get yourself a nice big steel plate. Never mind the monitor, you need to be concerned about the possible damage to yourself if your bed or chair is right up against it.

tce2506 · « **Reply #11 on:** September 24, 2004, 01:26:50 PM »

You can also use copper screening instead of steel, since steel is getting kind of expensive these days!

BigR · « **Reply #12 on:** September 24, 2004, 04:00:32 PM »

A good place to start if you want to shield agasint EMF... http://www.lessemf.com/emf-shie.html