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Old 08-03-2016, 09:29 PM   #28294
wodin
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Quote:
Originally Posted by DMcCunney View Post

The magnets are the read/write heads on the drive. (How many there are will depend on the drive and the number of disk platters.) When the drive is powered up, they are energized and a magnetic field is created. But distance counts: the heads float on a cushion of air a few microns above the spinning disk platter. If the head actually touches the spinning platter surface, you get a head crash and an unusable drive. It's a reason why drives are assembled in clean rooms and hermetically sealed. The tolerances are so fine a colloidal particle of cigarette smoke might cause a crash. But there is no magnetic field when the drive is powered off, and that head has to be really close to the platter when it's on to change the pattern of magnetic bits on the surface.
Uh...??? I'm looking at one right now that's attached to my file cabinet that I can't pry off with a screwdriver.
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