CHAPTER 4 THEORY OF DEVICE OPERATION
4.1Outline
4.2Subassemblies
4.3Circuit Configuration
4.4
4.5
4.6Read/write Circuit
4.7Servo Control
This chapter explains basic design concepts of the disk drive. Also, this chapter explains subassemblies of the disk drive, each sequence, servo control, and electrical circuit blocks.
4.1Outline
This chapter consists of two parts. First part (Section 4.2) explains mechanical assemblies of the disk drive. Second part (Sections 4.3 through 4.7) explains a servo information recorded in the disk drive and drive control method.
4.2Subassemblies
The disk drive consists of a disk enclosure (DE) and printed circuit assembly (PCA).
The DE contains all movable parts in the disk drive, including the disk, spindle, actuator, read/write head, and air filter. For details, see Subsections 4.2.1 to 4.2.5.
The PCA contains the control circuits for the disk drive. The disk drive has one PCA. For details, see Sections 4.3.
4.2.1Disk
The DE contains the disks with an outer diameter of 95 mm. The MPD3043AT has 1 disk. The MPD3064AT and MPD3084AT have 2 disks. The MPD3108AT and MPD3130AT have 3 disks. The MPD3173AT has 4 disks.
The head contacts the disk each time the disk rotation stops; the life of the disk is 40,000 contacts or more.
Servo data is recorded on each cylinder (total 96). Servo data written at factory is read out by the read/write head. For servo data, see Section 4.7.
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