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Spinpoint M8U-Internal Product Manual REV 3.4
21
INSTALLATION
CHAPTER 5 DISK DRIVE OPERATION
This chapter describes the operation of the Spinpoint M8U hard disk drive functional subsystems. It is
intended as a guide to the operation of the drive, rather than a detailed theory of operation.
5.1 Head / Disk Assembly (HDA)
The Spinpoint M8U hard disk drive consists of a mechanical sub-assembly and a printed circuit board
assembly (PCBA), as shown in Figure 5-1. This section describes the mechanism of the drive.
The head / disk assembly (HDA) contains the mechanical sub-assemblies of the drive, which are sealed
between the aluminum-alloy base and cover. The HDA consists of the base casting assembly (which
includes the DC spindle motor assembly), the disk stack assembly, the head stack assembly, and the rotary
voice coil motor assembly (which includes the actuator latch assembly). The HDA is assembled in a clean
room. These subassemblies cannot be adjusted or field repaired.
CAUTION: To avoid contamination in the HDA, never remove or adjust its cover
and seals. Disassembling the HDA voids your warranty.
The Spinpoint M8U hard disk drive models and capacities are distinguished by the number of heads and
disks.
The ST320LM008 have one (1) disk and two (2) read/write heads. The ST500LM016 has one (1) disk
and two (2) heads. The ST750LM024 have two (2) disks and four (4) read/write heads. The ST1000LM026
has two (2) disks and four (4) read/write heads.
5.1.1 Base Casting Assembly
A one piece, aluminum-alloy base casting provides a mounting surface for the drive mechanism and PCBA.
The base casting also serves as the flange for the DC spindle motor assembly. A gasket provides a seal
between the base and cover castings that enclose the drive mechanism.
5.1.2 DC Spindle Motor Assembly
The DC spindle motor assembly consists of the brush-less three-phase motor, spindle bearing (FDB)
assembly, disk mounting hub, and a labyrinth seal. The entire spindle motor assembly is completely
enclosed in the HDA and integrated to the base casting. The labyrinth seal prevents bearing lubricant from
coming out into the HDA.