Magnitized Computer Monitor

[zog]

I'm currently working on a project where a couple of computer monitors are picking up a magnetic field from somewhere. There are 2 computers at one of the stations and only one monitor is experiencing the problem. I monitored the voltage at the cubicle and ran a Gauss meter through the area and everything checks out fine. If you open the desk drawers below the screen the problem gets worse or if you pick up the screen and take it near the top of the cubicle the problem gets worse. There are only 2 monitors in the building that are doing this and they are on the second floor of a 3 story building and are about 100-150 feet away from each other. The building is being used a by a large cell phone company and they used an RF meter and still found no problem. The best ideas that I have come up with are that the cubicles themselves have become magnetized or the computers are sitting in "hot spots". Any ideas or comments would be a great help.

 

[ron]

Re: Magnitized Computer Monitor

Have you tried a different monitor in that physical location to be sure it's not a failing monitor?

 

[zog]

Re: Magnitized Computer Monitor

Yes, 3 different monitors to be exact

 

[marcspages]

Re: Magnitized Computer Monitor

You've not stated whether the computer screens are waving or just merely being "pulled" (alternating field or stable field).

M.

 

[jimwalker]

Re: Magnitized Computer Monitor

Look for any speakers near it,in ceiling ,floor under it,other side of wall.
You might try something else too if its possable.Maybe go in at 7 am or after 5 or during lunch.Turn every lighting outlet and receptacle off accept the one needed for that computer.It would tell you if your fighting a wiring problem or a other source.Perhaps some lights on a 3 way that are returning on just 1 wire in conduit.

[ April 22, 2005, 06:53 PM: Message edited by: jimwalker ]

 

[newt]

Re: Magnitized Computer Monitor

Have you tried running atemp circuit from the main service to elimanate any problems with the circuit it is plugged into.Then try moving monitor in another room to see if it goes away.Are the monitors near electric panels,vaults,overhead transmission lines.

 

[eutaw42]

Re: Magnitized Computer Monitor

If the lighting system is fluorescent (my guess) with standard magnetic ballasts then replace it with new energy saving T-8 lamps with electronic ballasts. May work and also save energy. By the way, I won an award (gold magnetic paper clip holder inscribed with customer satisfaction goal achievement) and placed it on my PC monitor --- took a few days to figure out what was wrong with the monitor. Oh well, dumb award.

 

[tom baker]

Re: Magnitized Computer Monitor

Try degausing the monitors, or use a flat panel display, they are not affected by the EM fields

 

[brian john]

Re: Magnitized Computer Monitor

Zog:

I do a lot of work with SHAKEY monitors, the most likely cause is as stated a magnetic filed. Most common problems we find is monitors located adjacent to electric rooms and neutral ground current. A neutral is grounded downstream from the service. If this is a 480/277 VAC building, check the neutral to ground bond connection for the transformer serving this area for current, then locate the source of the current, if this is a single 208/120 VAC transformer building or a straight 208/120 VAC bulilding locating the grounded neutral can be more involved but can be isolated, if you need any ideas on locating this email me.

Temporary circuit will not address the issue (and rather that trying this use an un-plugged UPS easier and quicker)and I doubt the Ballast are the issue (too far from the monitor to effect the screen. Changing to a flat screen will address the problem but not resolve the code violation which can lead to other problems and this should be corrected

[ May 02, 2005, 12:33 PM: Message edited by: brian john ]

 

[karl riley]

Re: Magnitized Computer Monitor

I have nothing to add to Brian's comment, but I am surprised you got no reading on your gaussmeter. (I assume the monitor was turned off when you measured). Some gaussmeters are designed for high-gauss industry use; you have to use one that measures in milligauss, and tenths of a milligauss. Monitors start flickering in 5 to 12 mG usually.

That's all I can add.
Karl

 

[mc5w]

Re: Magnitized Computer Monitor

The better monitors have a built-in degaussing coil and briefly energize it on power up.

 

[karl riley]

Re: Magnitized Computer Monitor

Degaussing has to do with removing DC magnetism in the coil. The magnetic field interference from AC souces is another issue, for which you need a milligauss meter.

Karl