My Pump is Spitting out a Monster Magnetic Field
 

Hello all, here's the problem I've got. My Danner 500gph pump is throwing a giant magnetic field that is interfereing with my monitor(Viewsonic A90), and they are a good 4 feet apart. If I run the monitor at anything lower than 100hz refresh rate, the entire screen waves and distorts with the field. This is a problem because it's a waste of a 19" monitor to run it at 1024x768 just so I can have a 100hz refresh rate. My question is, is there any way I can insulate either the pump or the monitor, so that the field is dampenend, and no longer will affect the monitor? Has anyone had run into this sort of thing before? If I can't dampen it, if I buy, say a 250gph pump, will it halve the size of the magnetic field? Thanks in advance for any input you guys have.
Cheers,
-Mr.Non-Toxic

I think you can shield it a bit. Are you sure it is the pump and not maybe a subwoofer?
-Kev

Positive.

That's normal.. Yeah, a smaller pump will have a smaller magnetic field. I'd just move them farther apart. :) Eheim pumps are EMI shielded, I've heard.

Yeah, I would move them farther apart, but lets just say that would be...hard. I've got a giant stationary liquid cooling array. (10 gallon res, dual rads, that huge mofo of a pump) It doesn't move easily. So I guess I'll just go out and buy a 250gph, I only bought the 500gph one because it was only $5 more than the 250, heh.

A question about shielding it, how exactly would one go about doing that? What kind of materials would I need? I have already tried placing large iron sheets between the pump and the monitor, no effect. What kind of magnetic shielding material do they use in speakers?

Spray on EMI shielding
Someone told me that he sprayed this on his Danner and it stopped messing with his monitor.. I haven't had a chance to buy some and test it myself.. Might be worth a shot..

Or you can just get an LCD such as:
http://kevin.procooling.com/lucky2.JPG
Hehhe ;)
-Kev

Una, yeah I'll prolly pick up a bottle of that and test it out. I'll tell yah how it goes. I've found that the pump only emits the field in certain directions, so maybe if I can tilt it, I can make it go away. I just don't feel like going for a swim in water-wetter right now to do it, heh. Kev, nice LCD, but my bro's Apple Cinema display is much much nicer ;). Thanks guys.

Did you connect them to earth?? If not you should ;).

If you take some leding metal (aluminium, cobber....) and place that around the pump, have some holes in the mettal, so the heat gets oway and connect it to earth. I don't remember if you should use thick metall or small, not the lenght but the other thing :), because there is diffrent shilding methodes for diffrent frecens, you know Hz. I belive you would be OK if you just take some leding metall and connect it to earth.

The painting you did speak about is the same princip, shilding the source I guees that the paint is leding power.

Good luck with you shilding.

Are the Enheim pump EMI shilded?

Maybe I'm missing something here, but aren't Al and Cu not effected by magnets? Seems to me you'd want something very permiable like Iron, permalloy or supermalloy (sp?). Then you'd want to wrap it in a sphere around the the pump so that it would conduct the flux lines around the pump instead of through your case and to your display.

Eheim pumps are indeed shielded. I can set my 1250 on top of my monitor or in physical contact with the glass diplay and see no distortion at all.

Actually you can't shield a magnetic field in any way except with a superconductor... I know you like things cool, but not that cool maybe :).

It might be possible to bend or tighten it though with iron, but how is beyond me.

No idea about shielding a magnet, but if you can conduct the flux lines through a small area then they won't be spread out through your room. You don't know the positioning of the poles on your pump, but you can just circle the whole thing with permable foil or strips and that should contain the field to the pump itself.

I had the same problem (still do). I took the U channel top of a bad PSU and put it over the pump, it helped a good bit but not perfect.

I think you got a pondmaster like me. the normal model 5 pumps are factory shielded.

Also, Copper shields by conducting the energy of the waves to ground.right?

[ 10-28-2001: Message edited by: resago ]

What exactly do you mean by 'connect them to the earth'? That is kind of hard to do in a room(if by earth you mean dirt). And Aluminum and Copper are not affected by magnets(At least I'm pretty damn sure of that, please correct me if I am wrong.). So wouldn't I want some sort of iron to do that? About the U shaped piece of sheet metal, how did that effect the field excatly? Where did it cut down on the distortion, and by how much? I've looked into mu-metal, which blocks magnetic fields, but it is like 3 grand for a square yard. Any of you guys heard of a Faraday cage? Someone suggested that to me, but it seems like I would have to put the monitor inside it for it to re-direct the field away from the monitor.

the sheetmetal got rid of about %50 of the waves.

before, I couldn't do 1600x1200x32 with my geforce 3, now I can no problem.

A magnetic field will induce an electric field of opposing direction, and same magnitude in any conductor placed near it - this is the principle mentioned above, also known as Lenz's law. Well, it goes something like that anyway :D. That's the reason for using a nice non magnetic material that is a good conductor (of electricity), then grounding it. A magnetic metal (ferrous, like iron) will merely be magnetised relative to the magnet, and extend the field.

I think, anyway... :D

Okay, that's pretty kickass. I have to run it at 1152x864@100hz just to get it not to distort, I would be more than satisfied if I could run it at 1280x1024 with no distortion. Thank you very much for that suggestion if it does indeed work, save me quite a few bucks. I got some sheet metal out in the back, I might make a box out of it and set it over the pump and see how it works. I'll let you guys know how it goes.

Komic, so you're saying I should surround it with copper and then ground the copper? If so, how the hell do I ground it? :confused: (I'm not to good with all that electrical stuff.)

it should be grounded just by touching your case. your case should be grounded cause its touching your power supply. your PS is grounded because of the 3 prong connector going into it from your wall. assuming you're not using a 2 to 3 prong adapter at the wall socket, all is well.


none of this applies if your case is aluminum of course.

I have the same pump less then 2 feet from my monitor and only 6 inches from my HDD without incident.

bet its not a pondmaster.

Aluminum is a good conductor (learned a new english word ;)) , so if you have a aluminium case it is earthet.

There did get a little discusion of what I mentioned. If you shield it good, the emi is reduced by around 50-80 dB.
But are you sure the pump is the reason???

[ 10-29-2001: Message edited by: the creature ]

[ 10-29-2001: Message edited by: the creature ]

yeah, just ground it to your case... I dunno what supply wires are like in the US... do you guys have 3 prong cables? or outlets? in Aus we have 3 outlets - 1 to live, 1 neutral, and a direct earth. By law all electrical equipment that isn't double insulated (means all electrical components are totally isolated) MUST have an earth connection (in Oz at least).

What I am working around to is "is your pump grounded?"

Also, I just did a bit of research, which popped up this for me Some college's stuff on EM shielding, which I definitely trust more than anything else I could say... :D ;) seems I might have been on the wrong track before...

Hope you manage to lick the problem...

Cheers, Komic.

edit: changed uni to college in URL. /edit

[ 10-29-2001: Message edited by: Komic ]

If want to shield the sorrundings from a magnetic source you have to create an easier path for the magnetic flux than the air.

The way to do that is to create a container made of iron or nickel. You don't have to make it spherical or any other tricky form an ordinary box will do the trick. And the strenth of the magnetic field determines the thickness of the material used however you probably don't have to make it thicker than 2-3mm.
Just make sure the "box" is closed on all sides, so u don't leave an open top like the do in the link that Komic posted.

Grounding the "box" isn't neccesery, since the magnetic field is alternating. However a grounding prevents any form of static electricity to collect on your "box" wich is BAD in a computer. Just make sure u connect the "box" at ONE place with a wire to the case of your computer. Making more than one connection can create alternating corrents in the computers case an that is also BAD.

Copper and Aluminum have the same magnetic permeability as air which makes them WORTHLESS as materials in this application.

Wow that was a long post. hope u have time to read it.