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#46240 - 26/12/2001 13:55 Re: High Temperature [Re: rjf]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31597
Loc: Seattle, WA
I have a question for all these people putting fans in their players.

What about magnetism? Don't these fans generate a small magnetic field around the fan motors? And doesn't the design of the cooling holes place the fan precariously over the magnetically-sensitive disk drives?
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Tony Fabris

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#46241 - 26/12/2001 13:57 Re: High Temperature [Re: tfabris]
smu
old hand

Registered: 30/07/2000
Posts: 879
Loc: Germany (Ruhrgebiet)
Hi.

Doesn't the motor that drives the disk also create a magnetic field?
Really, I don't think that would be a problem.

cu,
sven
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proud owner of MkII 40GB & MkIIa 60GB both lit by God and HiJacked by Lord

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#46242 - 26/12/2001 14:30 Re: High Temperature [Re: tfabris]
rjf
journeyman

Registered: 30/11/2001
Posts: 84
Loc: Oregon
I have an interesting perspective on this. I live within 50 feet of several sets of high tension, extremely high voltage (order of 600K volts) power lines.

Thus, I live in an extremely powerful magnetic field. I have to run all my computer monitors at 60Hz in order to avoid the affects of the field on standard CRT displays -- running at other refresh rates you can see extreme deflection of the picture.

I have lived like this for 3 years. Never lost a harddrive or floppy.

The field the fan throws off is infentesimal compared to the one I live in, I would guess.

rjf&

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#46243 - 26/12/2001 15:31 Re: High Temperature [Re: rjf]
wfaulk
carpal tunnel

Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
I have to run all my computer monitors at 60Hz ... I have lived like this for 3 years. Never lost a harddrive or floppy.
Of course, you now subsist on Visine and wear 3-inch thick glasses.
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Bitt Faulk

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#46244 - 26/12/2001 16:01 Re: High Temperature [Re: wfaulk]
rjf
journeyman

Registered: 30/11/2001
Posts: 84
Loc: Oregon
Yes. It's heinous -- 60hz refresh rates. But, the good news is, the house is sold, and I won't make the same mistake twice ;-)

rjf&

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#46245 - 26/12/2001 16:13 Re: High Temperature [Re: rjf]
wfaulk
carpal tunnel

Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
I used to work tech support for Nokia monitors. You'd be surprised (or not) at how many people called up complaining that since they got their new monitor and now their eyes were burning. Often, they were running at 56Hz interlaced. Oddly, this was back when Nokia was making sorta premium monitors and those folks had just paid for that premium. Folks don't even know what they're paying for.
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Bitt Faulk

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#46246 - 27/12/2001 06:08 Re: High Temperature [Re: tfabris]
beaker
addict

Registered: 19/08/2000
Posts: 588
Loc: England
I'm sure the magnetic field that these fans produce is far too small to be of any significance to the hdd(s). After all the Empeg team did toy with the idea of installing a fan (hence the holes in the lid). I think the reason they didn't go ahead was only because they felt that the player didn't need it and not for any risk from the magnetic field produced by the fan. As a little side note if you dismantle a dead (or alive for that matter if you're feeling sadistic) hard drive you'll find some Neodymium Iron Boron magnets which are extremely strong (and fragile). These are used to create a field that the head positioning coil can react against. Although these magnets are mostly enclosed in a Steel cage I'm sure some of the magnetic field leaks out and that this leakage amounts to more than the fan could ever produce. This is only my assumption though. There are some interesting experiments you can do with these magnets (most of which I haven't tried myself). One thing I have tried is to get two Aluminium plates spaced apart about 6mm to form a kind of hollow sandwich and drop one of these magnets through the gap. It seems like it's falling through Treacle. The falling magnet induces Eddy currents in the Ali plates. These Eddy currents create their own magnetic fields which react against the magnet's field slowing it's fall. If you do experiment with these magnets just make sure you keep them away from any Credit Cards, Monitors and any type of magnetic media.
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Marcus 32 gig MKII (various colours) & 30gig MKIIa

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#46247 - 27/12/2001 11:53 Re: High Temperature [Re: tfabris]
rmitz
member

Registered: 09/06/1999
Posts: 106
Loc: Pittsburgh, PA, USA
I do hope everyone is at least using brushless fans. That note about getting one at rat shack makes me have my doubts, though.
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#46248 - 27/12/2001 16:22 Re: High Temperature [Re: rmitz]
rjf
journeyman

Registered: 30/11/2001
Posts: 84
Loc: Oregon
I am fairly certain it is brushless -- I haven't seen a non-brushless fan in a long time.

But the more expensive have nice bearings, as opposed to a metal shaft in a collar. The radioshack one I got is the latter. It won't last as long, and is probably a bit louder than a bearing fan.

rjf&

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