magnetic field problem

[gizo]

hey all, i've been having problems after I water cooled my computer. My monitor is shaking violently when i change my refresh rate above 60 hertz. I believe my water pump is the main contributor to this effect. Is there anything I can do? I don't know the name of the pump, but I bought it off Chip Eckert at www.overclock-watercool.com. It is the resepump, but it is the 150gph version of it. Is there a way to shield the magnetic field of the pump? By the way, I have my pump connected to a UPS power supply unit. And my monitor is connected to a different power strip..

Please help.!!! SOS

http://shop.store.yahoo.com/webtroni...zaersupsh.html try this stuff

[NeosPirahnis]

I have the exact same problem, I have an eheim 1020 and its about........... a foot away from the monitor....... whenever I go above 60hz my screen shakes like a 500 mexican in a taco shop. .... Interesting to see that someone else has hasd the same problem

[Butcher]

Are you sure it's the pump? i.e. if you switch off the pump then does the monitor stop shaking?

[RedTalon19]

it could possibly be direct EMI interfearence or a feedback type loop through the circuit in which the 2 components are plugged into. the pump probably operates ona 60hz rate which might be your problem.

since your using a different outlet i doubt its that feed back type deal. try some shielding around the pump or move your monitor away temporaraily to see if it fixes the problem, if not then its the feedback through the outlet. might try a different circuit?

[Butcher]

Usually all outlets on the floor of a building are conencted in a ring, so you can still get some feedback even if they're plugged into different sockets.

[Techguy]

Ehiems are supposed 2 be shielded 2 prevent that. my 1250 has 0 shakin at 75Hz next 2 my monitor.
cheaper pumps lack that shielding. try 2 move them further apart.
also, u can put the pump on a UPS and the monitor on the wall, the batteries usually filter out bad line noise.

[gizo]

i do have my pump connected to my UPS and my monitor connected to the wall.. i don't know what i can shield my pump with that is attainable around the house.

[Techguy]

maybe a really big fearite bead (spelling?)
I really don't know how to shield it tho. atleast we know it's not signal noise now.

[revhed]

It all depends on what type of UPS u have. A UPS is basically a battery charger, a battery and an inverter. If you have a switching UPS it'll only run off the battery when the power drops so in normal running it will not filter out line noise. If you have a continuous UPS then it will filter line noise.
Basically if u have a switching UPS the problem may still be line feedback and if u have a continuous it is'nt.

[Mr Evil]

That spray will only help shield against an electric field. If the problem comes from a magnetic field, then you need to use a magnetically permeable material as shielding.

One of the best materials for this is soft steel, of the sort PC cases are made of. Surround either the source of the field (the pump) or the thing that is affected by the field (the monitor) completely in metal. Obviously, shielding the pump is more convenient though.

If the interference is being transmitted through the mains, then try using a mains filter on the pump and/or the monitor and make sure that no mains cables are run near the monitor or the monitor cable.

[gizo]

i have an APC 500VA.

[Vidboi]

I too have this same problem. I've tried just about everything, nothing seems to work. I have Danner 500gph sitting about 3 feet under my Viewsonic A90 19" and it causes it to flutter and shake at anything under 100hz. I've covered the entire pump in iron sheeting, then put iron between the monitor and the pump, moved the pump...nothing. I ran out of funding, so right now I'm stuck running my monitor at 1152x864@100hz. Try looking up a material called MuMetal, it dampens magnetic fields. You can buy it in sheets for pretty cheap, but if you buy anything thicker than paper I think it costs a few grand for a square yard. My advice, go spend the money and get yourself one of them Ehiem EM shielded pumps, save yourself the headache of trying to dampen the EM yourself. It's voodoo magic and you'll never understand it, trust me. Hope that helps.
Cheers,
-Mr.Non-Toxic

[Mr. Thompson]

Mr Evil Has the right idea on shielding the pump. A 16 gage cold rolled steel surrounding the pump with a 1/2" gap between the pump and the shield. If this does not work a second shield of expensive Mu metal over the steel shield with a 1/4" to 3/8" gap between the Mu metal and the steel.

[sloppycoder]

i dont reckon this is feedback from the mains circuit. putting it on a different wall socket will not help if it is. the whole house is wired, for example i can pick up my nintendo playing upstairs with a slightly fuzzy picture, on my tv downstairs!
fortunatly the n64 was made to go on a weird frequency that no channel uses.

a CRT basically works by using magnets to bend the path of positive ions to a specific spot on the back of the screen. the back is coated with stuff that glows when charge is applied (zinc i think). when the ions hit they deposite a little charge and the zinc glows.
what you are seeing is the magnetic field from the pump pulling the ions around in ways they shouldent be. the field will be reversing @ 60hz or whatever its running on.
i think the field is just coming right off your pump though.

i cant for the life of me understand why this dosent cause problems right across all of your refresh rates though. phase stuff? probaly.

anyway my friends dad is a emc technician who makes military laptops with no em emission, because in theory the "baddies" can pick up the signal (i know it sounds like ego building bullshit. thats what i thought till i saw the laptop he had at home. only a 233 but a 233 with ARMOUR!)
so if the problem dosent go away with steel coating ask and ill see if i can get any better ideas out of him.

slop

[Butcher]

Quick FYI, it's phosphor on the tube of a crt that glows

[gizo]

well, currently i wrapped my pump with aluminum shielding, but that doesn't do crap.

[Mr. Thompson]

Aluminum won't work because it's not a permeable metal. I should note that the solution in my previous post was from the senior engineer at a firm that specializes in magnetic shielding for the aerospace industry.

[gizo]

the only problem with your solution is that the stuff is relatively hard to attain. hey, when you say permeable mr. thompson, are you refering to the flexibility of the metal or are you alluding to another definition of permeable?

[resago]

the metal that old 286 powersupply's are housed in are pretty buff, you could probably put the pump in one of those and be done with it. My danner 500 is covered by the U channel portion of an old AT powersupply. I resolved 90% of the problem. I'm going to replace the POS with an ehiem soon.

[sloppycoder]

roflmao! sorry but i just saw the huge error in my last post. i said there were ions in your monitor. i meant electrons! if your not into chemistry stuff its like the difference between electricty and a chicken.

oops.

slop

[Butcher]

Originally posted by gizo:
the only problem with your solution is that the stuff is relatively hard to attain. hey, when you say permeable mr. thompson, are you refering to the flexibility of the metal or are you alluding to another definition of permeable?

By permeable I expect he means magnetically which basically means a ferrous metal, As noted the lid off an AT or ATX PSU does a good job.

[Dix Dogfight]

I'll just put a copy of my reply to another thread with the same problem/topic:

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 currents 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.

Magnetic permeability for a material determines how well it containes/blocks/transports magnetic flux.

Hmmm.. Maybe someone should make a small article about this and that would be the end of it.