To All Electromagnetic Engineers!

[TomPabst]

To all you electromagnetic engineers frequenting this Forum:

.....lol....well maybe somebody knows the answer?

How do I shield my monitor form electromagnetic interference?

I know I'm getting it...."DisplayMate Monitor Diagnostics" tells me I am (drifting moire lines)...and I know the source: Its from the three speaker towers I have (each has 18" PA speakers with huge magnets) that are from 2 to 3 feet from my monitor. Top that off...my monitor is a 21"...and those are already sensitive to magentic interference...even from the earth's magenetic field (according to documentation that comes with the monitor). My only solution is to build some sort of a "shroud" or box to cover the monitor...lined with some material (example: lined with aluminum foil...lol...it can't be that simple) that will shield or block some or all of the magnetic force from the speaker's magnets. Or, I could tear my house down...and move the speakers further away! I'm not worried about "heat" inside the monitor case....I already "exhaust" the heat with two 70mm case fans (this is a great trick by the way...my monitor runs about 50% cooler...and it shows in the graphic quality dramatically)....mounted on the top and rear of the monitor case. Also, if any of you guys are running your monitors with BNC cables...can you tell me how to "sync" off the red or blue....not the "green"......I'm tired of this "green" tint to my (what should be) black background?

Thanks in advance, for your help and information.....

Regards,

Tom


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Tom Pabst
www.pabst-racing.com

Sys Specs:
OpsSys: Win98SE,IE 5.50+ /DX8
Mobo: ASUS A7V133 (VIA KT133 chipset)
CPU: Athlon T-bird 1.2gig
Ram: 512 meg(PC133)
HD: 20 Gig
Vid: C-Labs Annihilator GeForce 2 Ultra (Nvidia 7.17 ref drivers)
Snd: SB Live 5.1 X-Gamer
Monitor: 21" KDS-Sony flat-screen
PS: Antec-400w-ATX PP403X
USB Dev's: mse, kybd, race wheel, Logitech FF joy.

[Paleo Pete]

Can't find anything on building your own, but did find plenty places that sell EMI shielding for monitors among other things.

http://www.magnetic-shield.com/

http://www.mushield.com/ also sells material and I think they have a design page.

http://www.amuneal.com/index.htm

http://www.exploratorium.com/snacks/magshield/index.html Article explaining an experiment, to see what works, and says that metal backed strapping tape should do the trick.

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Eagles may soar, but weasels don't get sucked into jet engines!
Note: Please post your questions on the forums, not in my email.

Computer Information Links (http://www.geocities.com/paleopete/)

[Reid]

Originally posted by TomPabst:
I already "exhaust" the heat with two 70mm case fans ....mounted on the top and rear of the monitor case.


And THAT doesn't bother the monitor? http://www.PCGuide.com/ubb/smile.gif I'll try that at home.

I don't know about using sync to change get rid of the green tint. I think TVs have SCREEN controls to adjust that. Does your monitor have any tint or color temperature controls?

Here is a Monitor Adjustment (http://www.guild.com/servlet/Guild/MonitorAdjustmentPage) page. Maybe the calibration images can help.



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reido@my-deja.com

Friends don't let friends install Windows ME

[TomPabst]

Guys...

First of all, "thanks" to P-Pete with those URL's. I have been to them all, got some good ideas. Especially, a good idea to not consider buying some sort of an EMI screen/filter for a 21" monitor. Did you look at the prices for those things? They were like $10K.....yikes. But, I did get some ideas of a few things to "try"...and I'm going to experiment with building a shroud/box....of some kind. I'll let you guys know what I come up with...and if it works.

The main thing I learned from those URL's....is "what" kinds of material are able to block EMI. That is....anything that **can** be magnitized...will block EMI to some degree or another. So, "steel" plate fits the definition. I am looking to find some sort of a "gausmeter".....they are expensive so I don't think I can run to Radio Shack for that item...lol. I may be able to rent one however....and that will help to tell me the EMI level produced by the speakers (and amplifier) around my monitor.

To answer Reid's remark regarding the "exhaust fans" for the monitor to suck hot air out of the monitor box....the "response" is:

Those fans are designed for that purpose. They are high-quality fans with very small magnetic motors (wound motors...no magnets) and they produce a very, very low EMI output. The fans would have to be sitting nearly on the electron gun inside the case to cause an e-beam deflection.

I get them from "3dfx Cool" up in Redmond, WA.....URL is: www.3dfxcool.com (http://www.3dfxcool.com) I also buy all my case fans and CPU fans from them, have done so for several years. They are $1 to $2 per fan more than the stuff I can buy locally....but, this is a "mom and pop" shop and his "hobby" is computer fans. He constantly searches for new fans....when he finds one he hasn't test yet, he does so. If its better than a fan he currently carries....he adds it to his inventory. Over the years.....I know I'm buying the best fans, pushing the most air for the least noise.....and the extra $1 to $2 per fan is far, far worth it! Bart's a good guy....his wife does all the order processing and shipping. These are nice people with a high quality product and a very reasonable price. If you buy fans.....you must give these people a trial run.

***End of Pabst' "3dfxCool" commercial...lol***

I'm actually surprised there isn't more "talk" about this EMI issue. I think few people at best, actually use programs to check and set their monitor display color, white-balance and focus. I know that I know almost no one who does this. I use a program called "DisplayMate"....and its not cheap ($80 last time I checked). I bought it a few years back...when I was making my first "big screen" monitor purchase (ended up being an ADI 6P+ 19")....because DisplayMate has this handy little "monitor testing" program that is small enough to export to a floppy...then you can take the floppy with you when going "shopping" for monitors. It rates the monitor on a comparative basis....right there in the store....and its great. I've used it for this purpose now several times since the original 19" purchase. One thing I've discovered in the three years using DisplayMate for purchasing/testing out candidates.....the more expensive monitors are not always the best "display quality" monitors. And, features you don't need just waste your money. I know I have saved myself several thousand dollars.....not bad for an $80 investment in DisplayMate. The HD installed program....in full-professional mode....is quite comprehensive. It takes nearly two hours to run through all the routines...but your monitor is "golden" when you are done! Then, there is a "daily" and "weekly" tweak routine as well, to help your monitor display quality remain essentially, perfect! This is a great program. You can DL it off the web, if you use a cc to make the purchase.

***End of Pabst' "DisplayMate" commercial.....lol***

I'm just full of all these "commercials" today. You guys want to hear about which laundry soap I use? Nah..guess not. ..........lol.....

Reid....on the color sync issue: I'm not totally sure I have the technology within full understanding. But, I found reading some of the backup info in DisplayMate....reference to monitor "sync" off one of the R,G,or B bands. It does this to set the "white balance" sync. If your monitor is "sync'd" off the "G" band (green band), then it gives a greenish "CRT green is what I call it" tint to your "black" background...which I hate (especially when you don't have the monitor white balance set properly). That's what I was referring to....its not a monitor "color tone" or "gamma" setting issue. It has to do with which "BNC" connector (or pin connector on the video card end of the monitor cable) is the "sync pin". By the way, if you are not using BNC video-card-to-monitor cabling...your monitor is operating somehwere around 80% of its full capability. I used to think that was BS...but DisplayMate proves it. If you have BNC connectors on your monitor....go buy the best BNC cables you can afford....the cheap ones are just that, cheap. I try to stay in the $100 range...they work best. If you don't have BNC connectors on your monitor....make sure your next one does! On monitors of 17" or smaller.....don't waste the money. But on 19" or higher (on 21" it is a must)....its a cheap way to get 20% more monitor for your money

Thanks for the "info"......and the "conversation."

Regards,

Tom


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Tom Pabst www.pabst-racing.com (http://www.pabst-racing.com)

Sys Specs:
OpsSys: Win98SE,IE 5.50+ /DX8
Mobo: ASUS A7V133 (VIA KT133 chipset)
CPU: Athlon T-bird 1.2gig
Ram: 512 meg(PC133)
HD: 20 Gig
Vid: C-Labs Annihilator GeForce 2 Ultra (Nvidia 7.17 ref drivers)
Snd: SB Live 5.1 X-Gamer
Monitor: 21" KDS-Sony flat-screen
PS: Antec-400w-ATX PP403X
USB Dev's: mse, kybd, race wheel, Logitech FF joy.

[This message has been edited by TomPabst (edited 02-10-2001).]

[Reid]

Maybe you could fabricate a shield with fine guage metal screen, should be inexpensive.

I thought the "drifting moire lines" might be coming from a motor or transformer, because I thought speaker magnets would cause stationary lines. Does using the monitor degauss help, even temporarily?



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reido@my-deja.com

Friends don't let friends install Windows ME

[mjc]

Just what the hell are you driving those beasts with (250W++)?

If that is the case it would be like having a motor or transformer (18" Subwoofers I assume?) near your monitor if they any closer than about 4 or 5 feet?

I can't come up with any other ideas on sheilding but you need something! Something like a Farraday cage should work (iron/steel framework around the monitor.

You can also shield the speaker boxes. The wire mesh might work better there and it should be just a tad prettier, too.

On the sync issue I can't come up with any thing other than in the TV studio where I went to college we controlled the sync from the source (switcher) so check out the vid card's settings (maybe even having to do a registry search).

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mjc
To ME or NOT to ME....

[This message has been edited by mjc (edited 02-11-2001).]