HDD hard drives as an important and familiar carrier of information, it has one unpleasant property, it is short-lived. And after the failure, it is completely useless. Most often, it ends up in the trash, or deliberately scrapped for recycling, which in our country is considered completely meaningless for a number of reasons, but the main one is the lack of a clear and widespread mechanism for recycling and separate waste collection. This topic is for a separate discussion, perhaps we will return to it. In the meantime, we find application in everyday life, because taking something apart is always interesting for an inquisitive mind! You can show the children the device of modern disks and have an “interesting” time.
How can we benefit from a non-performing drive? The only use that came to my mind was to get neodymium magnets out of it, which are known for their magnetizing strength and high resistance to demagnetization.
The process of disassembling and extracting magnets.
With a tool, this is not at all difficult to do, especially since the disk is ready to fulfill its final purpose.
We will need:
- Screwdriver six-pointed star (T6, T7… depending on the model).
- Thin flathead screwdriver or strong knife.
- Pliers.
I have a WD 3.5 inch hard drive that has served me faithfully for 4 years.
We unscrew the screws around the perimeter, but the casing will not open just like that, another one is hidden under the sticker. Apparently, this is such a seal, it is quite difficult to find it. The hidden screw is located on the axis of the magnetic heads (I marked it with a red circle in the photo), and in this area there is a hidden fastener. But you can not stand on ceremony, because we only need magnets, the rest has no value. You should get something similar, one or two metal plates with magnets. With the help of pliers and some effort, we bend the metal plate and carefully pry off the magnets. I was lucky, the plate turned out to be flat, and I glued it with super glue to the shelf on the desktop. The tool is at hand, it does not dangle on the table, and most importantly, we gave a second life to some part of the hard drive. I think everyone will find a use for magnets in everyday life.
In the photo - not all! Only those that I "sentenced" when I conceived this homemade !
Some are out of order. Others are simply outdated. (By the way, there is a general downward trend in quality: modern hard drives fail quite often. The old ones, for one or two gigabytes (or even much less), are all in good condition !!! But you can’t use them anymore - they have a very small the speed of reading information ... And there is very little memory in them.So it's not worth it.
But throw away - the hand does not rise! And I often wondered what could be made of them, or how to use them...
On the web, on request "... from a hard drive" are mostly "super talented" ideas for creating a grindstone !!! The people with a serious look show how to cut the case, glue the disk itself with sandpaper, and make a super-cool grindstone, powered by a computer power supply, and using its own hard drive motor!
I haven't tried it... But, I think, it will be possible to sharpen on such a grinder..... well, maybe, nails!.... And even then, if you don't press hard!!
And now, when I did, I remembered that there are powerful neodymium magnets in hard drives. And since during welding work "there are not many squares", then, at the end of the last home-made work, I immediately dismantled one of the hard drives to see what can be operated on)))
The magnet (I pointed to it with a red arrow) is glued to a metal bracket, which, in turn, is fixed with a screw.
In old hard drives, the magnet was one and more massive. The new ones have two. The second one is below:
Here's what I got after disassembling my disks:
By the way, the discs themselves also interested me. If anyone has any ideas for using them, please share in the comments...
To begin with, I decided to search the net to see if anyone had already invented this method of making welding corners?!)))
It turned out yes! They have already made these adaptations from hard drives! But there, a person simply placed a wooden board between the metal plates, to which he screwed magnets with screws. I immediately rejected this method for several reasons:
Firstly, the combination "arc welding + wood" is not very good!
Secondly, at the ends of these squares, a rather complex shape is obtained. And it will be very difficult to clean them! And he will take on a lot. Here is an example of a photo from my last post. They have a weak magnet on them, and he, after lying down on a workbench where they worked with metal:
And thirdly, I did not like that the square is obtained with very wide ends. That is, when welding some structures, the components of which are narrower than itself, it cannot be used.
Therefore, I decided to go the other way. To make, as with the "wooden" case, not the template plates of the body, but the end itself between them, but make this end smooth and closed.
In a previous publication, I already wrote that all magnets have poles, which, as a rule, are located on wide planes for permanent magnets. It is not desirable to "close" these poles with a magnetic material, so this time I decided to make the side plates of the case from a non-magnetic material, and the end plate from a magnetic one! That is, "exactly the opposite")))
So what I needed:
1. Neodymium magnets from old computer hard drives.
2. Plate made of "non-magnetic" stainless steel (for the case).
3. Thin magnetic steel.
4. Blind rivets.
First of all, I took up the manufacture of the case. I had just such a piece of stainless steel sheet. (I don't know the brand, but steel doesn't stick to a magnet).
With the help of a locksmith's square, I measured and cut out two right-angled triangles with a grinder:
In them, I also cut off the corners (I forgot to photograph this process). Why cut the corners, I already said - so as not to interfere with welding.
I did the exact adjustment of the corners manually on a piece of emery cloth spread over the plane of a wide profile pipe:
From time to time I put the blanks into the square and looked "at the light". After the corners were taken out, I drilled holes for the rivets, connected the plates through them with M5 screws, and checked the corners again! (The requirements for accuracy here are very high, and when drilling holes, I could make an error).
Next, I started making the magnetic plate itself, which, as I said, I want to place at the end of my square. I decided to make the thickness of the square 20 mm. Considering that the side plates are 2 mm thick, the end plate should be 16 mm wide.
To make it, I needed a thin metal with good magnetic properties. I found it in the case from a faulty computer power supply:
Straightening it, I cut out a strip, 16 millimeters wide:
It is on it that the magnets will be placed. But here one problem arose: the magnets, having a curved shape, do not fit in the width of my plate....
(A little about the magnets themselves. Unlike acoustic speakers, hard drives do not use ferrite, but the so-called neodymium magnets. They have a much higher magnetic force. But, at the same time, they are more fragile - although they They look like all-metal, they are made of sintered powder of rare earth metals, and they break very easily.
I did not peel off the magnets from the steel plates - I only need one working plane from them. I just cut off the protruding plates with a grinder, and, a little, the magnets themselves.
In this case, a conventional abrasive wheel (for steel) is used. Rare earth metals tend to ignite spontaneously in air in a highly crushed state. Therefore, do not be alarmed - the "fireworks" of sparks will be much stronger than expected.
I remind you!!!
Permanent magnets are afraid of strong heat!! And especially - sharp heating! Therefore, when cutting, they MUST be cooled!
I just put a container of water next to it, and periodically lowered the magnet into the water after I made a small incision.
So the magnets are cut off. Now they are placed on the strip.
Having inserted long M5 screws into the holes for rivets, and securing them with nuts, I bent the following complex structure along the perimeter of the template plate:
It is on it that the magnets will be located inside.
Often users are wary of magnets lying near electronics. Someone told us, or we saw for ourselves: these things can easily distort the image, or even permanently break expensive gadgets. But is the threat really that big?
Imagine the situation: magnets were bought as a gift for a child. In less than an hour, these things are near the computer, near the smartphone, near the TV ... Many months of my father's salary is under threat. The father of the family selects the "magnets" and throws them on the far shelf, but then he thinks: maybe not everything is so scary?
This is exactly what happened to DigitalTrends journalist Simon Hill. For the search for truth, he decided to turn to experts.
Matt Newby, first4magnets:
“People have such ideas from old electronic devices - for example, CRT monitors and televisions, which were sensitive to magnetic fields. If you place a strong magnet near one of these devices, you could distort the image. Fortunately, modern TVs and monitors are not so sensitive.”
What about smartphones?
“The vast majority of magnets you encounter every day, even some of the very strong ones, will not adversely affect your smartphone. In fact, it also contains several very small magnets at once, which are responsible for important functions. For example, wireless magnetic induction charging is used.”
But it's too early to relax. Matt warns that magnetic fields can still interfere with some sensors, such as the digital compass and magnetometer. And if you bring a strong magnet to your smartphone, the steel components will be magnetized. They will become weak magnets and prevent the compass from being properly calibrated.
Don't use a compass and think it doesn't concern you? The problem is that other, sometimes very necessary applications need it. For example, Google Maps compass is required in order to determine the orientation of the smartphone in space. It is also needed in dynamic games. For owners of the latest iPhone models, magnets can even interfere with taking pictures - after all, the smartphone uses optical image stabilization. Therefore, Apple does not recommend official case makers to include magnets and metal components in their products.
Next up are hard drives.
The idea that magnets simply destroy the contents of the HDD is still very popular today. Suffice it to recall an episode from the cult series Breaking Bad, where the main character Walter White destroys digital dirt on himself with a huge electromagnet. Matt speaks again:
“Magnetically recorded data can be damaged by magnets—this includes things like cassette tapes, floppy disks, VHS tapes, and plastic cards.”
And yet - is it possible that the character of Bryan Cranston did in real life?
“It is theoretically possible to damage a hard drive with an incredibly strong magnet if you bring it directly to the surface of the drive. But hard drives have neodymium magnets in them... a normal size magnet won't hurt them. For example, if you attach magnets to the outside of your PC's system unit, it will have no effect on the hard drive."
And if your laptop or PC runs on an SSD, there is nothing to worry about at all:
"Flash drives and SSDs are not affected by even strong static magnetic fields."
We are surrounded by magnets at home, says the expert. They are used in every computer, speaker, TV, motor, smartphone. Modern life without them would be simply impossible.
Perhaps the main danger posed by strong neodymium magnets is the danger of being swallowed by a young child. If you swallow several at once, they will be attracted to each other through the walls of the intestines, Matt warns. Accordingly, the child cannot avoid peritonitis (inflammation of the abdominal cavity - ed.), and, therefore, immediate surgical intervention.
What does a modern hard disk drive (HDD) look like inside? How to take it apart? What are the names of the parts and what functions do they perform in the general information storage mechanism? The answers to these and other questions can be found here below. In addition, we will show the relationship between Russian and English terminologies describing hard drive components.
For clarity, let's take a look at a 3.5-inch SATA drive. It will be a brand new terabyte Seagate ST31000333AS. Let's examine our guinea pig.
The green screw-on plate with a visible track pattern, power and SATA connectors is called the electronics board or control board (Printed Circuit Board, PCB). It performs the functions of electronic control of the hard disk. Its work can be compared to laying digital data in magnetic prints and recognizing it back on demand. For example, as a diligent clerk with texts on paper. The black aluminum case and its contents are called the HDA (Head and Disk Assembly, HDA). Among specialists, it is customary to call it a "bank". The body without contents is also called the HDA (base).
Now let's remove the printed circuit board (you will need a T-6 asterisk screwdriver) and examine the components placed on it.
The first thing that catches your eye is a large chip located in the middle - the System on a chip (System On Chip, SOC). It has two major components:
- The central processing unit that performs all the calculations (Central Processor Unit, CPU). The processor has input-output ports (IO ports) for controlling other components located on the printed circuit board and transmitting data via the SATA interface.
- The read/write channel is a device that converts the analog signal coming from the heads into digital data during a read operation and encodes the digital data into an analog signal during a write operation. It also monitors the positioning of the heads. In other words, it creates magnetic images when writing and recognizes them when reading.
The memory chip is a conventional DDR SDRAM memory. The amount of memory determines the size of the hard disk cache. This circuit board has 32 MB Samsung DDR memory, which in theory gives the disk a 32 MB cache (and this is exactly the amount given in the specifications of the hard drive), but this is not entirely true. The fact is that the memory is logically divided into buffer memory (cache) and firmware memory (firmware). The processor needs some memory to load firmware modules. As far as is known, only the manufacturer of HGST lists the actual amount of cache in the specification sheet; As for the rest of the disks, we can only guess about the actual cache size. In the ATA specification, the compilers did not expand the limit laid down in earlier versions, equal to 16 megabytes. Therefore, programs cannot display more than the maximum volume.
The next chip is a spindle motor and voice coil controller that moves the head unit (Voice Coil Motor and Spindle Motor controller, VCM & SM controller). In the jargon of specialists, this is a “twist”. In addition, this chip controls secondary power supplies located on the board, from which the processor and the preamplifier-switching chip (preamplifier, preamp) located in the HDA are powered. This is the main consumer of energy on the printed circuit board. It controls the rotation of the spindle and the movement of the heads. Also, when the power is turned off, it switches the stopping engine to the generation mode and supplies the received energy to the voice coil for smooth parking of the magnetic heads. The VCM controller core can operate even at 100°C.
Part of the control program (firmware) of the disk is stored in flash memory (marked in the figure: Flash). When power is applied to the disk, the microcontroller first loads a small boot-ROM inside itself, and then rewrites the contents of the flash chip into memory and starts executing code from RAM. Without the correct code loaded, the drive won't even want to start the engine. If there is no flash chip on the board, then it is built into the microcontroller. On modern drives (somewhere from 2004 and newer, but the exception is Samsung hard drives and they also have stickers from Seagate), flash memory contains tables with codes for mechanics and heads settings that are unique for this HDA and will not fit another. Therefore, the “transfer controller” operation always ends either with the fact that the disk is “not detected in the BIOS”, or is determined by the factory internal name, but still does not give access to data. For the Seagate 7200.11 drive under consideration, the loss of the original contents of the flash memory leads to a complete loss of access to information, since it will not be possible to pick up or guess the settings (in any case, such a technique is not known to the author).
On the R.Lab youtube channel there are several examples of re-soldering a board from a defective board to a working one:
PC-3000 HDD Toshiba MK2555GSX PCB change
PC-3000 HDD Samsung HD103SJ PCB change
The shock sensor reacts to shaking that is dangerous for the disk and sends a signal about it to the VCM controller. The VCM immediately parks the heads and can stop the disk from spinning. Theoretically, this mechanism should protect the drive from additional damage, but it doesn't work in practice, so don't drop the discs. Even when falling, the spindle motor can jam, but more on that later. On some discs, the vibration sensor has an increased sensitivity, reacting to the slightest mechanical vibrations. The data received from the sensor allows the VCM controller to correct the movement of the heads. In addition to the main one, two additional vibration sensors are installed on such disks. On our board, additional sensors are not soldered, but there are places for them - they are indicated in the figure as “Vibration sensor”.
There is another protective device on the board - the transient voltage suppression (TVS). It protects the board from power surges. During a power surge, the TVS burns out, creating a short circuit to ground. This board has two TVS, 5 and 12 volts.
The electronics for older drives were less integrated, and each function was split into one or more chips.
Now consider the HDA.
Under the board are the contacts of the motor and heads. In addition, there is a small, almost imperceptible hole (breath hole) on the disk body. It serves to equalize pressure. Many people think that there is a vacuum inside the hard drive. Actually it is not. Air is needed for the aerodynamic takeoff of heads above the surface. This hole allows the disk to equalize the pressure inside and outside the containment. On the inside, this hole is covered with a breath filter, which traps dust and moisture particles.
Now let's look inside the containment area. Remove the disc cover.
The lid itself is nothing special. It's just a steel plate with a rubber gasket to keep dust out. Finally, consider the filling of the containment area.
Information is stored on disks, also called "pancakes", magnetic surfaces or plates (platters). Data is recorded on both sides. But sometimes the head is not installed on one of the sides, or the head is physically present, but disabled at the factory. In the photo you see the top plate corresponding to the highest numbered head. The plates are made of polished aluminum or glass and are covered with several layers of various compositions, including a ferromagnetic substance, on which, in fact, the data is stored. Between the plates, as well as above the top of them, we see special inserts called separators or separators (dampers or separators). They are needed to equalize air flows and reduce acoustic noise. As a rule, they are made of aluminum or plastic. Aluminum separators are more successful in cooling the air inside the containment area. Below is an example of an air flow model inside a HDA.
Side view of plates and separators.
Read-write heads (heads) are installed at the ends of the brackets of the magnetic head unit, or HSA (Head Stack Assembly, HSA). The parking zone is the area where the heads of a healthy disk should be when the spindle is stopped. With this disc, the parking zone is located closer to the spindle, as can be seen in the photo.
On some drives, parking is done in special plastic parking areas located outside the plates.
Western Digital 3.5” Drive Parking Pad
In the case of parking heads inside the plates, a special tool is needed to remove the block of magnetic heads; without it, it is very difficult to remove the BMG without damage. For external parking, you can insert plastic tubes of suitable size between the heads and remove the block. Although, there are also pullers for this case, but they are of a simpler design.
A hard drive is a precision positioning mechanism and requires very clean air to function properly. During use, microscopic particles of metal and grease may form inside the hard drive. For immediate cleaning of the air inside the disk there is a recirculation filter. This is a high-tech device that constantly collects and traps the smallest particles. The filter is in the path of air flows created by the rotation of the plates
Now let's remove the top magnet and see what is hidden under it.
Hard drives use very powerful neodymium magnets. These magnets are so powerful that they can lift 1,300 times their own weight. So do not put your finger between the magnet and metal or another magnet - the blow will be very sensitive. This photo shows the BMG limiters. Their task is to limit the movement of the heads, leaving them on the surface of the plates. BMG limiters of different models are arranged differently, but there are always two of them, they are used on all modern hard drives. On our drive, the second limiter is located on the bottom magnet.
Here's what you can see there.
We also see here the coil (voice coil), which is part of the block of magnetic heads. The coil and magnets form the VCM drive (Voice Coil Motor, VCM). The drive and the block of magnetic heads form a positioner (actuator) - a device that moves the heads.
A black plastic piece of complex shape is called a latch (actuator latch). It comes in two types: magnetic and air (air lock). Magnetic works like a simple magnetic latch. The release is carried out by applying an electrical impulse. The air latch releases the BMG after the spindle motor has revved up enough for air pressure to push the detent out of the voice coil path. The latch protects the heads from flying out of the heads into the working area. If for some reason the latch did not cope with its function (the disk was dropped or hit while it was on), then the heads will stick to the surface. For 3.5" discs, the subsequent inclusion due to the greater power of the motor will simply tear off the heads. But in 2.5 "motor power is less and the chances of recovering data by releasing native heads" from captivity "are quite high.
Now let's remove the block of magnetic heads.
Accuracy and smoothness of movement of the BMG is supported by a precision bearing. The largest part of the BMG, made of aluminum alloy, is usually called a bracket or rocker (arm). At the end of the rocker are heads on a spring suspension (Heads Gimbal Assembly, HGA). Usually the heads and rocker arms are supplied by different manufacturers. A flexible cable (Flexible Printed Circuit, FPC) goes to the pad that mates with the control board.
Consider the components of the BMG in more detail.
A coil connected to a cable.
Bearing.
The following photo shows the BMG contacts.
The gasket (gasket) ensures the tightness of the connection. Thus, air can enter the inside of the disk and head unit only through the pressure equalization hole. The contacts on this disc are coated with a thin layer of gold to prevent oxidation. But on the side of the electronics board, oxidation often occurs, which leads to a malfunction of the HDD. You can remove oxidation from the contacts with an eraser (eraser).
This is a classic rocker design.
The little black pieces at the ends of the spring hangers are called sliders. Many sources indicate that sliders and heads are one and the same. In fact, the slider helps to read and write information by raising the head above the surface of magnetic disks. On modern hard drives, the heads move at a distance of 5-10 nanometers from the surface. By comparison, a human hair is about 25,000 nanometers in diameter. If any particle gets under the slider, it can lead to overheating of the heads due to friction and their failure, which is why the purity of the air inside the containment is so important. Also dust can cause scratches. From them, new dust particles are formed, but already magnetic, which stick to the magnetic disk and cause new scratches. This leads to the fact that the disc is quickly covered with scratches or, in the jargon, "sawed". In this state, neither the thin magnetic layer nor the magnetic heads work anymore, and the hard drive knocks (death click).
The reading and writing elements of the head themselves are located at the end of the slider. They are so small that they can only be seen with a good microscope. Below is an example of a photograph (on the right) through a microscope and a schematic representation (on the left) of the relative position of the writing and reading elements of the head.
Let's take a closer look at the surface of the slider.
As you can see, the surface of the slider is not flat, it has aerodynamic grooves. They help to stabilize the flight altitude of the slider. The air under the slider forms an air cushion (Air Bearing Surface, ABS). The air cushion maintains the flight of the slider almost parallel to the surface of the pancake.
Here is another slider image.
Head contacts are clearly visible here.
This is another important part of the BMG, which has not yet been discussed. It is called a preamplifier (preamplifier, preamp). A preamplifier is a chip that controls the heads and amplifies the signal coming to or from them.
The preamplifier is located directly in the BMG for a very simple reason - the signal coming from the heads is very weak. On modern drives, it has a frequency of more than 1 GHz. If you take the preamp out of the containment area, such a weak signal will be strongly attenuated on the way to the control board. It is impossible to install an amplifier directly on the head, since it heats up significantly during operation, which makes it impossible for a semiconductor amplifier to work; vacuum tube amplifiers of such small sizes have not yet been invented.
More tracks lead from the preamp to the heads (right) than to the containment area (left). The fact is that a hard disk cannot simultaneously work with more than one head (a pair of writing and reading elements). The hard disk sends signals to the preamplifier, and it selects the head that the hard disk is currently accessing.
Enough about the heads, let's disassemble the disk further. Remove the top separator.
Here's what it looks like.
In the next photo, you can see the containment area with the top separator and head assembly removed.
The lower magnet became visible.
Now the clamping ring (platters clamp).
This ring holds the stack of plates together, preventing them from moving relative to each other.
Pancakes are strung on a spindle (spindle hub).
Now that nothing is holding the pancakes, let's remove the top pancake. Here's what's underneath.
Now it’s clear how the space for the heads is created - there are spacer rings between the pancakes. The photo shows the second pancake and the second separator.
The spacer ring is a high-precision part made of non-magnetic alloy or polymers. Let's take it off.
Let's pull everything else out of the disk to inspect the bottom of the HDA.
This is what the pressure equalization hole looks like. It is located directly below the air filter. Let's take a closer look at the filter.
Since the outside air necessarily contains dust, the filter has several layers. It is much thicker than the circulation filter. Sometimes it contains particles of silica gel to combat air humidity. However, if the hard drive is placed in water, it will be drawn in through the filter! And this does not mean at all that the water that has got inside will be clean. Salts crystallize on magnetic surfaces and sandpaper instead of plates is provided.
A little more about the spindle motor. Schematically, its design is shown in the figure.
A permanent magnet is fixed inside the spindle hub. The stator windings, changing the magnetic field, cause the rotor to rotate.
There are two types of motors, with ball bearings and with hydrodynamic (Fluid Dynamic Bearing, FDB). Ball bearings were discontinued over 10 years ago. This is due to the fact that they have a high beat. In a hydrodynamic bearing, the runout is much lower and it runs much quieter. But there are also a couple of downsides. First, it can jam. With balls, this phenomenon did not occur. Ball bearings, if they failed, then began to make a loud noise, but the information was read at least slowly. Now, in the case of a bearing wedge, you need to remove all the disks with a special tool and install them on a serviceable spindle motor. The operation is very complex and rarely leads to successful data recovery. A wedge can arise from a sudden change in position due to the large value of the Coriolis force acting on the axis and leading to its bending. For example, there are external 3.5” drives in the box. The box stood vertically, touched, fell horizontally. It would seem that it did not fly far?! But no - the wedge of the engine, and no information can be obtained.
Secondly, lubricant can leak out of the hydrodynamic bearing (it is liquid there, there is quite a lot of it, unlike the gel lubricant used by ball bearings), and get onto the magnetic plates. To prevent the lubricant from getting on the magnetic surfaces, a lubricant with particles that have magnetic properties and magnetic traps traps them is used. They also use an absorption ring around the place of possible leakage. Overheating of the disc contributes to leakage, so it is important to monitor the temperature regime of operation.
Clarification of the connection between Russian and English terminology was made by Leonid Vorzhev.
Update 2018, Sergey Yatsenko
Reprinting or quoting is permitted provided the link to the original
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