Disassembling a hard disk

Hard disks with spinning platters are going away very fast. During easter cleanup in my workshop I found a old 750 GB hard disk, and decided not only to take it to the local recycling station but to disassemple it to see how it it constructed. During the disassembly I took some photos with my phone - they are not near professional quality but they are still usefull with the comments.

The drive is a Seagate Barracuda ES.2 (data sheet) with a SATA 3Gb/s interface. It runs with 7200 RPM which made it rater usefull when it was released. I stopped using the drive when I really swithched to SSD in my workstation. There is nothing wrong with the drive - it just went obsolete to me.

To remove the cover there are at first six T9 screws. But hidden behind the sticker there are three more screws, also T9.

With the cover removed there is direct access to the inner components. Also this is the point of no return to use the drive again as the disk is now filled with dirt from the normal atmosphere.

On the backside of the hard disk the circut board is placed. It is fastned with T6 screws but none hidden. The connection from the board to the inner drive is through some contacts. The picture below shows two sets of contacts with one set of three contacts for the electrical engine spinning the platters and another set of four by five contacts for the head.

A closer look at the board shows chips from Seagate and Samsung. The external connections are direct from the board to the physical interfaces.

Under the board and a metallic sticker there is another hidden T9 screw. This holds the head.

The connection for the head is on a small board. But is quite easy pulled out and disconnected from the head.

The head unit movements are controlled with a coil on the back of the arms and two powerfull static magnets. The top magnet is only held in place by the magnetic force and can be removed with a small screwdriver.

The arm with heads and coil is one unit together with a small board. This head unit is removed without any tools.

A closer look at the head unit from another angle show a small board and the arms with the physical heads to transport electro-magnetic signals to and from the platters.

Going from buttom to top on the picture below it looks like the buttom arm only hold one head to communicate with the lower side of the lowest platter.

The next two arms holds two heads each to communicate with the upper side of the platter below the arm and the lower side of another platter placed above the arm.

The fourth arm hold only one head to communicate with the upper side of the top platter.

There is a fifth arm but this hold no heads and is not connected on the board.

I guess that the head unit was designed and partly constructed for up to four platters where this hard-drive only has three platters as shown later.

The bottom magnet that was under the head unit is also quite easy removed without any tools. I guess that the small plastic spring to the right on the picture below is some sort of anti-vibration or shock-absorbtion.

The spindle holding the platters on the axle is removed with six T9 screws.

The first platter is removed without tools. Between the platters there is a open ring of metal fastned to the chassis. I guess this is to stabilize the platters when they are spinning. Also there is a inne ring to give space for the heads.

After all three platters are removed the chassis looks quite empty. I have tried to lay out the components to show the stack from buttom to top. Between the platters there is a inner ring and a open outer ring.

The outher part of the electric motor spinning the platters is removed with brute force as indicated by the tools on the picture below. The outer part is the static magnetics where the inner part is the coils. How the outher part is fastned I can't see. There are no obvious traces of glue.

The three-pin connector for the motor on the back of the chassis is glued on but easy removed with a small screwdriver.

The inner part of the motor with the coils is removed with brute force and another set of tools.

All in all I count about 55 major components in the hard drive. In that there is about 31 screws.

Looking at modern storage there has certainly been some major changes. Compared to a NVMe storage unit with only one major components in a single board and no mechanics the technological span is amazing. But also compared to an elder SAS SSD drive typically with one board, around three screws and two metal half-shells the technological evolution is significant.

In general and looking back the flash storage was a paradigm shift where all our notes on spindles, RPMs and configuration tricks like short-strike suddenly were to no use. With NVMe many rules of thumb were obsolete. As PCIe (PCI-SIG) evolve we will see new fantastic features also on NVMe and CXL. But the next paradigm shift does not come from evole the current mainstream technology but when a completely new technology matures and push to the side the mainstream tech.