Magnetic Shielding

[danfman]

I have a cocktail game and I am getting some magnetic distortion appearing on my monitor near one of my Ultrastiks.  Would I be OK if I put a sheet of steel to act as a barrier inside my control panel box between the magnets on the joystick and monitor?

[protokatie]

If you do, make sure the shielding is grounded, it works better that way as it will be much more efficient at inducing a current and therefor "absorbing" the magnetic energy coming off of the stick. Query: Does this distortion happen only when you move the stick or is it just because the magnets are too close and distorting the shadow mask? If it is the later case, you may need to move the sticks a few inches further away. Dunno how much shielding will help in that case.

[Beretta]

ya a piece of sheet metal will do the trick.. the thicker the better it'll dampin the magnetic field greatly.. put a sheet between teh monitor and the joystick.. if you're still getting it then put a 2nd sheet.

[doctorhifi]

Perhaps a small bucking magnet?

Bucking magnets are used to reduce the stray magnetic field of a woofer.  This will allow you to put the woofer closer to a CRT TV screen.  The magnet is glued to the back of the existing magnet system with the magnets repelling each other.  When the magnet are centered, the magnetic field will cancel and it will be possible to glue the magnet on.

http://forum.arcadecontrols.com/index.php?topic=24297.0

[BobA]

Magnetic shielding is based on the magnetic properties of the material used.   It works as both magnetic and RF shielding at the same time.   However RF shielding eg copper grid etc does not perform as magnetic shielding so the grounding and conductive properties of the metal are not important.  What is important is that it is responds to magnets and will divert the magnetic fields away from what ever you want to sheild.

[danfman]

To clarify, I had the machine assembled for a few weeks then started noticing a corner turning green.  A quick investigation made me realize the corner turning green was awfully close to the magnet in my joy stick.  Player 1 is orientated a little further from the monitor and isn't causing problems at the moment. 

I am a little confused on whether I need to ground the the metal barrier.  I know magnetism actually has effect on very few metals, but steel is one of them.  I have had experience shielding cables from high voltage interference and know it is a good idea to ground those because of high voltage interference, but I think magnetic interference may be a whole 'nother ball game.  So should I ground it or not?

[KissMyWookie]

While steel should do the trick, there are specialized materials for magnetic shielding which won't add the extra weight to your cabinet.

The following website has magnetic shielding materials and faq's:
http://lessemf.com/mag-shld.html

Steve

[Minwah]

I thought lead was very good at magnetic shielding. But I haven't tried it so cannot say for sure...

[AndyWarne]

We have magnetic shields for the U360. Drop me an email.

Andy

[TeamTEOR]

I am having a bad issue as well with shaking on my Billabs monitor due to electrical magnetic interference. I don't think my marquee light is causing problems, so I am turning my attention to the computer tower which is laying down on the bottom of the cab and the speakers.

I have the two computer tower cabinet outer panels on top of each other trying to block any EMI from the power supply, fans, or drives. The 2.1 subwoofer system is mounted just under the monitor, so I can reach the power & volume controls. The two stereo speakers were removed from their simple wood containers and mounted into the spots where the original stock speakers went.

Is there a better way to get the 2.1 sound without the EMI? Maybe I need to buy an actual set of computer speakers that has a manual on/off switch rather than a push button control.

Does anyone know if those "Smart Strip LCG3 Energy Saving Power Strip with Autoswitching Technology" give off any EMI?

Tom

[Beretta]

most likely the subwoofer is not shielded so you'll need to shield the monitor.. a piece of sheet metal (thicker the better) between the subwoofer and the monitor will eliminate it.

[KissMyWookie]

most likely the subwoofer is not shielded so you'll need to shield the monitor.. a piece of sheet metal (thicker the better) between the subwoofer and the monitor will eliminate it.

Make sure you use a ferrous metal, as copper or aluminum won't do anything to block the magnetic interference.

[TeamTEOR]

Since there was a lot of time today I opened up the machine today. The subwoofer made no difference if it was on or off, so it is not coming from the transformer in the housing (as you guys said it could be from the magnet). The speakers up top are tiny things (3 inch ovals with no visible magnets). I moved the smart strip out of the cab and put it on the floor outside the cab about a foot away from it on the floor, still had the shake.  The Linksys USB network adapter had no effect on the shake as well. The marquee light was unplugged as well so there is not EMI from it.  So at this point it seems that I will need to just hook up the monitor to my laptop (with the main PC off) and see if I continue to get the shake. If so I will pull out the subwoofer and the speakers to see if it goes away. Worse case is that I pick up a shielded woofer or use an ferrous based metal sheet metal like you guys suggest. I'll let you know what I find, thanks!
Tom

[TeamTEOR]

It has something to do with the monitor itself. I took everything out, including the tower. The tower was about 4 feet away from the monitor thanks to a nice VGA cord and still it still has the shake.

Maybe it is time to contact Billabs and ArcadeVGA on this. Thanks gang, it is not a magnetic shielding issue.
Tom