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Recover HD Using a Magnet

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Re: Recover HD Using a Magnet

#31

Post by 4ad »

pontifier wrote: post #16
mirimir wrote: post #5

Earlier quoted context omitted.

It's changing magnetic fields that wipe HDDs. Such as powerful electromagnets. In a clean (enough) room, they could have opened the drive, and just poked the actuator arm. Decades ago, I had a HDD that wouldn't spin up unless I nudged the platter with a pencil erasor. Very near the center, of course. There was a hole in the case, in just the right place, with Al tape over it.

Doesn't even have to be a very clean room... I played around with an old 1 gig drive years ago. My friends and I opened up the case so we could watch the drive doing it's thing. We did a fresh os install and watched as it formatted the disk and copied files. The head was remarkably strong, and would move so fast it looked like it was in 2 places at once while copying files. It was fun to stick a screwdriver between t…

My first HDD has a 540MB drive, I ran DOS. Eventually I upgraded to newer computers, and I opened the old drive, and put in on the wall on display. It stood there for at least a decade, possible 15 years, before I moved to a different country. Before leaving, I decided to connect the old drive to a computer, just for kicks.

Remarkably, I could read data off it. Not much, file i/o mostly ended up in failure, but I could at least see the file structure. I did not expect this.

Re: Recover HD Using a Magnet

#32

Post by mlyle »

FabHK wrote: post #25
mlyle wrote: post #10

Earlier quoted context omitted.

Magnetic field falls off with inverse cube of distance once you're past the approximate size of the magnet. Not to mention that the drive itself is in a ferrous enclosure that provides a lot of shielding... the magnetic field you applied at 6 inches is approximately nothing.

Isn't it inverse square?

No. Magnetic fields fall off as 1/d when d is small compared to the size of the magnet, progressing to 1/d^3 when d is large compared to the magnet. (E.g. weird edge case-- it's inversely proportional to distance from an infinitely long wire).

Electromagnetic radiation from point sources falls off as 1/d^2.

Re: Recover HD Using a Magnet

#33

Post by egdod »

FabHK wrote: post #25
mlyle wrote: post #10

Earlier quoted context omitted.

Magnetic field falls off with inverse cube of distance once you're past the approximate size of the magnet. Not to mention that the drive itself is in a ferrous enclosure that provides a lot of shielding... the magnetic field you applied at 6 inches is approximately nothing.

Isn't it inverse square?

No, it’s a dipole moment instead of a monopole like electric charge. It goes as 1/r^3 in the far field.

Re: Recover HD Using a Magnet

#34

Post by hinkley »

netsharc wrote: post #19
rgj wrote: post #14

My anecdote: Around 1993 I had a Commodore Amiga with an A590 external hard drive. A big enclosure that could be connected to the expansion port on the left of an Amiga 500, containing a very precious 20MB hard disk. One day, it stopped working. I tried everything but I couldn’t get it to work. A friend offered to take a look at it so I put it in my backpack and took the train to my friend. When connected to his A500…

Might as well share mine: one day the magic smoke[0] left a lot of components on my PC, including the HD with no backups. I saw the board was replacable, so that's what I did: bought an identical disk on eBay, some torx screwdrivers, transplated the good board to the dead disk, and it worked perfectly fine. [0] http://www.catb.org/jargon/html/M/magic-smoke.html

I've heard tell that some data recovery companies have a stable of the controller cards from popular drive models. If swapping the card works, you get your data cheap. Beyond that it gets spendy.

Re: Recover HD Using a Magnet

#35

Post by lallysingh »

jacquesm wrote: post #26

Clever! I'm stuck on a problem right now as well, I'm trying to boot an old server (Supermicro, dual CPU) to verify something and for the life of me I can't figure out what is wrong with it. It doesn't do anything when you power it up, even the power led on the board doesn't light up. Forcing the powersupply to 'on' does light up the LED but the system still won't boot. Already put a fresh 3V cell in it, stripped it…

Check your IDE cables

Re: Recover HD Using a Magnet

#36

Post by jacquesm »

lallysingh wrote: post #35
jacquesm wrote: post #26

Clever! I'm stuck on a problem right now as well, I'm trying to boot an old server (Supermicro, dual CPU) to verify something and for the life of me I can't figure out what is wrong with it. It doesn't do anything when you power it up, even the power led on the board doesn't light up. Forcing the powersupply to 'on' does light up the LED but the system still won't boot. Already put a fresh 3V cell in it, stripped it…

Check your IDE cables

SCSI system, already pulled the controller out and disconnected the backplane. Really weird this one. But thank you for the suggestion. In fact, that's the whole reason I want to boot it, the drives are a hardware raid which is hard to port to a machine where the controller won't fit.

Re: Recover HD Using a Magnet

#37

Post by bewilderbeast »

My story:

In 1996 or 97, a friend brought me his Compaq Deskpro, the SCSI HDD had stopped working. No sound at all, dead. Tried everything, checked voltages, reconnected cables trying to clear any oxidation. Wouldn't spin at all. Well, called it a night.

Next day, decided to take it out of the chassis for a last test, connected outside. Not only it spun, it worked fine!!! WTH????

Well, into the chassis it went. Nothing. Dead. Whaa..??? Outside again, it worked. In the chassis, dead. Outside, worked. Scratched my head... With it working outside, just tried to place it on top of the chassis. It spun down and stopped. Took it away, it spun up. Got it close again to the chassis, it spun down again... Scratched my head again... Gave up, left it disconnected outside for the day.

Next day tried it again and this time it worked outside of and in the chassis... My thoughts? The chassis was magnetized or something...

Worked for a couple more years.

Re: Recover HD Using a Magnet

#38

Post by glennvtx »

I have fixed a ton of drives, in general. Board replacements, swapping platters, head swaps, etc. Some takeaways: I started doing this under tupperware, and that worked. I built a "cleanroom" out of a new sandblasting cabinet, and that worked better. Later i built a laminar flow bench out of a cheap kobalt tool-box and some plexiglass, and that was better still.

Swapping the control boards works on some makes (wd), make certain it is exactly the same model and revision. exactly. "close enough" never worked for me, not even once.

By far just a slight "spin" by hand along the axis of travel of the disk, a quick gentile flicking motion, works to unfreeze the spindles of most stuck drives.

Some drives responded to a gentle heating of the spindle bearing with the hot air.

Use dd_rescue.

"Spinrite" is complete horse-shit, don't listen to anyone saying otherwise.

Most drives people brought in were just corruptions, photorec and it's associated programs (testdisk) are also invaluable..

Re: Recover HD Using a Magnet

#39

Post by tjoff »

pontifier wrote: post #16
mirimir wrote: post #5

Earlier quoted context omitted.

It's changing magnetic fields that wipe HDDs. Such as powerful electromagnets. In a clean (enough) room, they could have opened the drive, and just poked the actuator arm. Decades ago, I had a HDD that wouldn't spin up unless I nudged the platter with a pencil erasor. Very near the center, of course. There was a hole in the case, in just the right place, with Al tape over it.

Doesn't even have to be a very clean room... I played around with an old 1 gig drive years ago. My friends and I opened up the case so we could watch the drive doing it's thing. We did a fresh os install and watched as it formatted the disk and copied files. The head was remarkably strong, and would move so fast it looked like it was in 2 places at once while copying files. It was fun to stick a screwdriver between t…

I'd say it needs to be pretty clean. Back in the day it was a thing to remove the hard-drive cover and replace it with plexiglass. Once densities got to around 100 GB (don't remember the specifics but somewhere around 100 */2) it turned out that noone was successful with even momentarily open the drive chassi without ruining some part of the platter due to dust.

Re: Recover HD Using a Magnet

#40

Post by jacobush »

rgj wrote: post #14

My anecdote: Around 1993 I had a Commodore Amiga with an A590 external hard drive. A big enclosure that could be connected to the expansion port on the left of an Amiga 500, containing a very precious 20MB hard disk. One day, it stopped working. I tried everything but I couldn’t get it to work. A friend offered to take a look at it so I put it in my backpack and took the train to my friend. When connected to his A500…

The manual (or some kind of leaflet with it) of the MFM 10 megabyte drive of an IBM XT even mentioned, that the drive could seize up if the bolts were too tightly or unevenly tightened. Sure enough, I had to adjust them one fine day.
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