Fujitsu MAX3147NC Maintenance Manual page 23

(1) Disks
The disks have an outer diameter of 70 mm (2.8 inch) and an inner diameter of 25 mm (0.98 inch).
The disks are good for at least 50,000 contact starts and stops.
(2) Heads
The MR (Magnet - Resistive) of the CSS (contact start/stop) type heads are in contact with the
disks when the disks are not rotating, and automatically float when the rotation is started.
(3) Spindle motor
The disks are rotated by a direct-drive hall-less DC motor. The motor speed is controlled by a
feedback circuit using the counter electromotive current to precisely maintain of the specified
speed.
(4) Actuator
The actuator, which uses a rotary voice coil motor (VCM), consumes little power and generates
little heat. The heads at the end of the actuator arm are controlled and positioned via feedback of
servo information in the data.
The heads are positioned on the CCS zone over the disks when the power is off or the spindle
motor is stopped.
(5) Air circulation (recirculation filter, breather filter)
The disk enclosure (DE) configures a clean room to keep out particle and other contaminants. The
DE has a closed-loop air recirculation system. Using the movement of the rotating disks, air is
continuously cycled through a filter. This filter will trap any particle floating inside the enclosure
and keep the air inside the DE contaminant free. To prevent negative pressure in the vicinity of the
spindle when the disks begin rotating, a breather filter is attached. The breather filter also
equalizes the internal air pressure with the atmospheric pressure due to surrounding temperature
changes.
(6) Read/write circuit
The read/write circuit utilizes a read channel mounted with a head IC that supports high-speed
transmission and an MEEPR4ML (Modified Enhanced Extended Partial Response Class 4
Maximum Likelihood) modulation/demodulation circuit in order to prevent errors being triggered
by external noise and to improve data reliability.
(7) Controller circuit
The controller circuit uses LSIs to increase the reliability and uses a high speed microprocessing
unit (MPU) to increase the performance of the SCSI controller.
C141-E229 1-7