magnetic interference with monitor?

[Monkeyleg]

I just picked up a new HEPA air purifier, and it sits just to the left of me on a small filing cabinet. It's for grabbing the cigarette smoke.

I run two 21" monitors side by side, and it's causing the left side monitor to flutter (the screen looks like I'm degaussing it). It doesn't affect the right monitor unless I put the purifier right up to it.

I'm concerned about whether this is harmful to the monitor, so I'm keeping the left monitor off unless I absolutely need it.

Am I being overly concerned, or could the interference from the air purifier damage the monitor over time?

[AJ Dual]

It probably won't hurt it. The magnetic field from the motor is just bending the electron beams inside.

It could burn something out by fighting with one of the yokes inside, or by inducing current in components that don't want/need it, but I've never seen that happen in my 15 years working in IT.

In general terms, a magnetic field will only "hurt" the monitor if it's strong enough, and close enough to magnetize parts of the CRT like the shadow-mask or other ferrous parts, then It'll permananly pull the beams around and screw up the image sometimes beyond the ability of the built in degausser to correct it.

[charby]

probably not, just move the filter a little further away if you can. I get this all the time with coworkers who have started putting them in their office.

You could look at building some sort of Faraday cage to put over the filter to reduce or end the interference.

-C

[caseydog]

Quit smoking ! ta-da problem solved You can subtract the cost of a new monitor over in the "cost to quit" thread !

[Monkeyleg]

caseydog, I was just waiting for a comment like yours.

Charby, the odd thing is that the purifier interferes only with the left-side Radius monitor, not with the right side Sony. And I have to move the purifier several feet away before the interference stops.

I guess I'll just leave the monitor turned off when I don't need it, and not smoke when I do.

[AJ Dual]

I just had a thought, you could try changing the monitor's refresh rate. You don't wantto go too low, or the flicker will be ungodly at high-res, but changing it to something that dosen't synch with the motor may help.

[Headless Thompson Gunner]

Magnetic fields can destroy a monitor over time.  Don't leave the air purifier near the monitor.

[CAnnoneer]

If you switch to LCDs for screens, the EM field will have no e-beam to bend.

A grounded Faraday cage would work for electric but not magnetic fields.

If the magnetic field is strong enough, it can magnetize ferrous components in your monitor and produce a permanent distortion in the image. Turning the monitor off will not stop the magnetization. Finally, if the EM field is strong enough and/or varies quickly enough, it will induce emf that can indeed cause damage to circuitry. But, that effect is orders of magnitude too weak, unless you intend to detonate a nuke next to your monitor (or build and use an EMP cannon).

[Monkeyleg]

Where do all of you folks learn this stuff?

God, I am dumb.

[Fly320s]

Probably like I did: by playing with magnets on my parent's TV.

[charby]

Canoneer

Did't know that about the Faraday cage, learned something new today.

Dick

I learned a lot but doing, I fix computers and other electronic stuff everyday so I picked it up along the way. I still got a lot to learn, I usually learn something new every week.

-C

[280plus]

Seeing how it's A/C current, wouldn't the swapping of fields 60 times a second cancel out any magnetizing of ferrous components? Just curious.

I recall messing up a tv screen more than once playing with magnets. The patterns are so COOL!

Then I'd take them down to the local electronics shop and they'd use that magic ring thing on them (it almost DOES look like they're doing magic) and then they were all better. I'm guessing the degaussing circuit on monitors is something similar?

[Firethorn]

Then I'd take them down to the local electronics shop and they'd use that magic ring thing on them (it almost DOES look like they're doing magic) and then they were all better. I'm guessing the degaussing circuit on monitors is something similar?

Yep.  You can make your own degausser('Magic Wand') fairly easily.  Build an electromagnet capable of taking 120 volts, put a plug on it and plug it in.  

Degausers work on the principle that it's slightly easier to demagnitize something than to magnetize it.  So you hit what you want to demagnetize with alternating fields(electromagnet hooked up to AC will work just fine).  That and field strength is less the further away the magnet is, so you gradually pull it back once you've gotten rid of most of the magnetization before you switch it off (so you don't get that last polarity).

edit:  The air purfier might be using DC for something, is it an ionizing purifier?

[Monkeyleg]

I don't think it's an ionizing purifier. Just has this HEPA filter on it.

HTG, I know this may sound dumb, but does having the air purifier running while the monitor is turned off damaging in any way?

Prior to this air purifier, I had two stacked on top of each other. They just used some sort of treated paper filters, so they trapped the smoke, but not the odors. Oddly, though, they never affected either monitor at all.