In Figure 6 we show the H.DA after we removed the logic board. There you can clearly see the spindle motor and its contacts – which connect this motor to the logic board –, and also the contacts from the devices inside the HDA, namely the heads and the voice coil actuators.

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Figure 6: HDA without the logic board.

On hard drives targeted to desktops, the spindle motor rotates at 5,400 rpm, 7,200 rpm or even 10,000 rpm, depending on the drive. The faster this motor rotates, the faster data can be read from the platters. Hard drives targeted to laptops usually rotates at 4,200 rpm.