usb flash drive

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Joel727

I magnetized usb flash drive with the center of a metal candle holder
which was magnetic. How do I un-magnetize my usb flash drive?
This action was an error on my part, forgetting that the center of
dish was magnetic.
The drive can not be seen by any of the 5 computers I tried it on,
this means not lights are on, in the usb jump drive.
If I could see the drive, I could copy the files on it.
 
Joel727 said:
I magnetized usb flash drive with the center of a metal candle holder
which was magnetic. How do I un-magnetize my usb flash drive?
This action was an error on my part, forgetting that the center of
dish was magnetic.
The drive can not be seen by any of the 5 computers I tried it on,
this means not lights are on, in the usb jump drive.
If I could see the drive, I could copy the files on it.
Click to expand...

The flash chip is not affected by the state of the adjoining
magnetic fields. You did not disrupt its operation when you
held a magnet near it. Flash is sensitive to very high electrical
fields, radiation, or perhaps UV light (only if the top of
the chip was removed so light could strike it).

Years ago, the ability of light to erase flashable memory, was
a feature. These devices had a "window" on top, so you could
erase the contents by shining a UV light on the device for 20 minutes
or so. Now, flash can be erased electrically, so they no longer
put a window on them like this. I used to erase trays of these
under UV light in the lab.

http://www.antronics.co.uk/portfolio/flashram/eproms.jpg

*******

If you use a degaussing coil to remove the residual magnetism,
that could induce an AC voltage on some of the conductors. I
don't see a particularly good reason to be using a degaussing
coil on it. So that would be a needless risk. A degaussing
coil will not revive the flash.

Flash memory can be damaged by static electricity. Maybe
that is what broke it. Or, perhaps one of the four
conductors leading to the USB connector, is cracked.
And that electrical connection failure is what is
preventing it from working. Many flash sticks are poorly
designed, such that if any force is applied to the metal
connector on the end, it can cause a connection to crack
and fail.

The flash is usually separated into at least two chips.
The design looks like this. Small capacity devices have
one Flash chip, while higher capacity ones can hold two.

USB ------------- Controller ----- Raw Flash
connector Chip Memory (1 or 2 chips)

There is a picture of that, here, showing room for two
flash chips.

http://en.wikipedia.org/wiki/File:Usbkey_internals.jpg

At a data recovery firm, they can probe the flash memory
chip directly, to bypass a failed controller chip. That
is about the only opportunity for data recovery on a
USB flash. If it is the Raw Flash chip which has failed,
then your data is gone.

Paul
 
The flash chip is not affected by the state of the adjoining
magnetic fields. You did not disrupt its operation when you
held a magnet near it. Flash is sensitive to very high electrical
fields, radiation, or perhaps UV light (only if the top of
the chip was removed so light could strike it).

Years ago, the ability of light to erase flashable memory, was
a feature. These devices had a "window" on top, so you could
erase the contents by shining a UV light on the device for 20 minutes
or so. Now, flash can be erased electrically, so they no longer
put a window on them like this. I used to erase trays of these
under UV light in the lab.

http://www.antronics.co.uk/portfolio/flashram/eproms.jpg

*******

If you use a degaussing coil to remove the residual magnetism,
that could induce an AC voltage on some of the conductors. I
don't see a particularly good reason to be using a degaussing
coil on it. So that would be a needless risk. A degaussing
coil will not revive the flash.

Flash memory can be damaged by static electricity. Maybe
that is what broke it. Or, perhaps one of the four
conductors leading to the USB connector, is cracked.
And that electrical connection failure is what is
preventing it from working. Many flash sticks are poorly
designed, such that if any force is applied to the metal
connector on the end, it can cause a connection to crack
and fail.

The flash is usually separated into at least two chips.
The design looks like this. Small capacity devices have
one Flash chip, while higher capacity ones can hold two.

     USB ------------- Controller ----- Raw Flash
     connector         Chip             Memory (1 or 2 chips)

There is a picture of that, here, showing room for two
flash chips.

http://en.wikipedia.org/wiki/File:Usbkey_internals.jpg

At a data recovery firm, they can probe the flash memory
chip directly, to bypass a failed controller chip. That
is about the only opportunity for data recovery on a
USB flash. If it is the Raw Flash chip which has failed,
then your data is gone.

    Paul
Click to expand...

Thank you It is the data on the device, not the cost of the
device. The USB drive is a 64Mb Lexar jump drive. I am going use a
compass to check the strength of the magnetic field from the drive.
I am thinking of using my tape head de-magnetizer device that I used
to use for my the reel to reel tape recorder, this is the smaller
probe device, not the large device for erasing entire reels.
The files on it are important, particularly the MS Excel file with all
my passwords. I will be doing a better job of backing up copies from
now on.
 
The flash chip is not affected by the state of the adjoining
magnetic fields. You did not disrupt its operation when you
held a magnet near it. Flash is sensitive to very high electrical
fields, radiation, or perhaps UV light (only if the top of
the chip was removed so light could strike it).

Years ago, the ability of light to erase flashable memory, was
a feature. These devices had a "window" on top, so you could
erase the contents by shining a UV light on the device for 20 minutes
or so. Now, flash can be erased electrically, so they no longer
put a window on them like this. I used to erase trays of these
under UV light in the lab.

http://www.antronics.co.uk/portfolio/flashram/eproms.jpg

*******

If you use a degaussing coil to remove the residual magnetism,
that could induce an AC voltage on some of the conductors. I
don't see a particularly good reason to be using a degaussing
coil on it. So that would be a needless risk. A degaussing
coil will not revive the flash.

Flash memory can be damaged by static electricity. Maybe
that is what broke it. Or, perhaps one of the four
conductors leading to the USB connector, is cracked.
And that electrical connection failure is what is
preventing it from working. Many flash sticks are poorly
designed, such that if any force is applied to the metal
connector on the end, it can cause a connection to crack
and fail.

The flash is usually separated into at least two chips.
The design looks like this. Small capacity devices have
one Flash chip, while higher capacity ones can hold two.

     USB ------------- Controller ----- Raw Flash
     connector         Chip             Memory (1 or 2 chips)

There is a picture of that, here, showing room for two
flash chips.

http://en.wikipedia.org/wiki/File:Usbkey_internals.jpg

At a data recovery firm, they can probe the flash memory
chip directly, to bypass a failed controller chip. That
is about the only opportunity for data recovery on a
USB flash. If it is the Raw Flash chip which has failed,
then your data is gone.

    Paul
Click to expand...

I will check for cracks and breaks on the connectors on the Lexar 64mb
jump drive, one data recovery company thought they could recover the
data with a cost of $250-$400. I can not justify spending that much,
making backup copies is now in order.
 
I will check for cracks and breaks on the connectors on the Lexar 64mb
jump drive, one data recovery company thought they could recover the
data with a cost of $250-$400.  I can not justify spending that much,
making backup copies is now in order.
Click to expand...

Well, all I can tell you is, the magnetism didn't do it. One of the
other failure modes must be responsible. If it is the purchase price
of the Lexar that is the concern, does Lexar have a warranty at all ?
Do you still have the purchase receipt ?

In the article here, the "Floating Gate" section describes how your
data is stored.

http://en.wikipedia.org/wiki/Flash_memory

    "Because the FG [floating gate] is electrically isolated by its
     insulating layer, any electrons placed on it are trapped thereand,
     under normal conditions, will not discharge for many years."

So the information is an electrical charge, which has no way to escape
from the gate electrode, on each memory bit. That is how the info
is stored. Waving a magnet around, still doesn't provide a way
for the electrons to leave the floating gate.

    Paul
Click to expand...

thanks again I just checked, no magnetic field - the compass
needle does not move. I checked the four conductors for cracks after
cutting the metal cover off the top half of the end of the device. No
cracks, I just place clear tape over the four conductors for the same
effect as a worn credit card, no go. I then placed a 2nd piece of
clear tape, still no light on in the usb drive, I also opened my
computer window and refreshed several times. I will connect a USB
cable. This drive is too old no warranty, I did talk to Lexar once,
maybe I should call them again for a different opinion that the first
person. thanks again
 
If you place clear tape over the USB connector contacts, you're
insulating them. This definitely will prevent the flash drive from
working.
Click to expand...

Okay I will remove the tape
 
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