Magnetic field strength on a Danner Mag 3

[rocketmanx]

Was installing my Danner Mag 3 and was wondering how strong the magnetic field is with this thing running? I have a VERY full box and am concerned about emf with my scsi drives hanging in the lower drive cage of my Chieftech.

Anybody have there's mounted internally?

I'm gonna wait on some input before I wipe a scsi drive, an emf shielded box would be easy enough to build but the heat buildup would require more fans which is what I'm trying to get away from.

Thanks for any input.

Pete

[Cathar]

The magnetic field strength at 10cm distance is about 10000000 times weaker than necessary to flip a bit on a hard drive platter.

The actual number is probably a bit higher than that. I was being conservative.

[rocketmanx]

Thanks Cathar

I checked it with several small pieces of steel and it didn't have enough unpowered to even appear to have magnets inside. When I pulled the front inlet though it was quite apparent the strength of the inner magnets from the impeller.

So no worries then, pumps roughly 1 cm from the HD's, a lot of misinformation floating around about the danner pumps?

[Cathar]

Well let's put it this way. Inside the high speed SCSI hard drives are the rare-earth magnets that are used for the drive head seek actuators. These magnets are very, very powerful. Stick them onto a good piece of high ferrous steel, and it takes about 50lbs of effort to separate the magnet again.

There are two of these magnets in every hard drive, and they are positioned about 1cm from the drive platters, and the hard drive uses electromagnetic force to drive the positioning of the drive heads.

It amazes me how much misinformation there is in general about hard drives. It is extremely hard to flip the data on them. You could take your average fridge magnet and sit it on the platter, and aside from any physical damage, the data will probably still be safe.

[rocketmanx]

Thanks again

I like to know the facts as well. Without proper knowledge of HD's it's impossible to know without expert input, unless you're crazy enough to experiment I'm not that crazy with my expensive eqipment. And I'm sure you've seen the many posts stating to keep the DM 3's away from HD's, that's why I posted here, you seem to me to be more than just an enthusiast. Perhaps some engineering field?

[killrtech99]

I too would like to thank Cathar for the info. I have posted regarding the Danner M3 only to state that it does not have any shielding as far as I can tell. I believe that I mentioned that I had no idea as to what the actual ramification of the fact is save for the impact on the monitor. I have used my monitor to gauge what level of EMI a pump is throwing off and I can tell you the Via Aqua 1300 and the Danner M3 both disturb the picture on the monitor at several feet away when placed in line with the spin axis of the rotor. My friend has an Eheim 1250 and you could tape that thing to the monitor and it would cause no interference. I give kudos to Eheim for their shielding.

That being said, I have thought about the fact that a "spray" of electrons would be quite easy to disturb and that explains why unshielded pumps seem to easily disturb the picture. I just simply had no idea what the "degree of difficulty" in knocking HDD bits around might be and I did not have opportunity to test it myself.

I currently use an external box (for a variety of reasons), but I have been contemplating taking a stab at going all internal on my Aux gaming rig. One of the things holding me back is that I was running on the supposition I would need to get an Eheim (for its shielding properties) and I didn't want to spend the bling for what is an occassional use item. I'm starting to get my "project juices" flowing again based on this info. I thank you Cathar, my wife does not.

[killernoodle]

People say they rattle the monitor when they are close up, but mine has no problems. I am happy to report that I have never had a problem with the pump

[Turbokeu]

CRT monitors, as opposed to hard disks, are quite sensitive to magnetic fields.
Except for my old 17" Nec Multisync 5FG, just to gain access to the electronics you need to remove kilograms of shielding....
It's bigger and deeper than my actual 22" Iiyama...(but then except the CRT tube...)
As Cathar said, don't worry about your HDD...

CD

[killernoodle]

I think the monitor I am using, a Samsung Syncmaster 955df is shielded. I took the plastic cover off once and the entire monitor is covered with a layer of sheet metal with holes in it for ventilation. This may have something to do with the fact that my computer is in no way affected by the pump.

[killrtech99]

kn: What pump do you have? Also, what is the orientation of your pump to the monitor? I can have my pump right next to the monitor providing I have the spin axis more or less perpendicular to the monitor. I have a Viewsonic A90 (not F, generation back from that). I've been tempted to crack the case but I never have. Even if I see some sort of shielding, I know it doesn't stop the pump problems so.....eh, one of these days.