Author Topic: What are these things found inside HDDs?  (Read 412 times)

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Offline aix

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What are these things found inside HDDs?
« on: February 08, 2020, 06:42:26 pm »
I've been taking apart various HDDs.  I'd be curious to know what these things are:
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Offline Benta

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Re: What are these things found inside HDDs?
« Reply #1 on: February 08, 2020, 06:47:42 pm »
Shock sensors. If the HDD is dropped or hit, they detect the shock, making the controller retract the head immediately to avoid damage to the surface of the disk.

 

Online RoGeorge

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Re: What are these things found inside HDDs?
« Reply #2 on: February 08, 2020, 06:51:19 pm »
Activated charcoal acting as humidity absorbent and air filter.
« Last Edit: February 08, 2020, 06:57:26 pm by RoGeorge »
 

Online edpalmer42

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Re: What are these things found inside HDDs?
« Reply #3 on: February 08, 2020, 06:58:26 pm »
I think they're air filters.

Except for the newest high capacity drives (~10 TB) which are full of helium, all hard drives have a breather to equalize air pressure so the cover doesn't bulge down and touch something.  The breather has to be well filtered so that nothing but clean air is allowed in.

I've also seen air filters that are in the path of the 'wind' that the spinning platters create.  These catch and hold any particulate matter that might be created by, for example, a small head slap.  By capturing this material, it helps to prevent a small problem from growing into a fatal one.

Ed
 
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Offline aix

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Re: What are these things found inside HDDs?
« Reply #4 on: February 08, 2020, 07:20:45 pm »
I think they're air filters.

Except for the newest high capacity drives (~10 TB) which are full of helium, all hard drives have a breather to equalize air pressure so the cover doesn't bulge down and touch something.  The breather has to be well filtered so that nothing but clean air is allowed in.

This makes total sense, thank you.  I've just looked, and there's indeed a hole on the outside of each of the enclosures right where the filter is.
 

Offline mikerj

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Re: What are these things found inside HDDs?
« Reply #5 on: February 08, 2020, 07:43:08 pm »
Shock sensors. If the HDD is dropped or hit, they detect the shock, making the controller retract the head immediately to avoid damage to the surface of the disk.

The accelerometers used for this function are small IC's soldered onto the main controller PCB.
 
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Offline ArthurDent

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Re: What are these things found inside HDDs?
« Reply #6 on: February 08, 2020, 07:56:52 pm »
Definitely an air filter to allow clean air to flow to equalize pressure inside the drive.

 


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