Fujitsu MAN3367FC - Enterprise 36.7 GB Hard Drive, Product/Maintenance Manual

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Principle of Operation
8-2 C141-E133-02EN
8.2.1 Disks
The disk configuration of each DE is shown in Figure 1.2.
•
The DE for the MAN3735 series contains 4 disks whose external diameter is 84 mm and internal
diameter is 25 mm.
•
The DE for the MAN3367 series contains 2 disks whose external diameter is 84 mm and internal
diameter is 25 mm.
Each time disk rotation stops, the read-write heads touch the disk surfaces. Disk surfaces withstand
at least 20,000 head touch operations at disk rotation start and stop.
8.2.2 Heads
The read/write head configuration is shown in Figure 1.3.
There are 8 read/write heads for the MAN3735 series and 4 for the MAN3367 series. These heads
float up from the surface of the disk automatically when the spindle motor’s speed has reached a
certain speed.
8.2.3 Spindle mechanism
The spindle mechanism consists of a disk stack assembly and a spindle motor. The disk stack
assembly is directly driven by the direct drive type DC spindle motor. The rotational frequency of
this spindle motor is 10,025 min
-1
(10,025rpm). A counter-electromotive force is generated by the
drive current in the spindle motor coil. A fixed rotational frequency of the spindle is maintained by
comparing the frequency of the counter-electromotive voltage with the reference frequency generated
by the crystal oscillator.
8.2.4 Actuator
The actuator consists of a voice coil motor (VCM) and a head carriage. The voice coil motor moves
the head carriage to the inner or outer side of the disk. The head carriage position is controlled by
feeding back servo information read by the heads.
8.2.5 Air filters
There are two filters in the disk drive, the breathing filter and the circulation filter. The breathing
filter is used to conduct filtered air into and out of the DE. Starting or stopping the disk generates
heat in the spindle motor in the DE, causing temperature variation in the DE. This temperature
variation expands or compresses the air in the DE causing the filtered air to come in or go out of the
DE. At times when the atmospheric air pressure changes, such as when the disk drive is shipped by
airmail, filtered air enters the DE.
The circulation filter catches dust or dirt that may get inside the DE. Air is continuously circulating
inside the drive and passing through the circulation filter, utilizing a closed loop air circulation
system that uses the blower effect of the rotating disks.