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2.1.7 Actuator
The actuator is mounted on a pivot beside the
disk and carries the heads across the disk to the
specified track. The data heads and the servo
head are attached to one end of the actuator
and a coil is wound on the other end. The
coil, which is located in the field of a permanent
magnet, moves when current passes through it.
This moves the servo and data heads in an arc
across the disk surface. Track crossing and
track following information is obtained from
the servo tracks and picked up by the servo
head to position the data heads over the
required data track. An output preamplifier
for the servo head is mounted on the actuator
close to the servo head.
During all power down conditions, the actuator
retracts against the inner (spindle) stop. A mag-
netic catch holds the actuator in the retracted
position. Therefore, the heads are over the land-
ing zone after power down.
2.1.8 Actuator Lock
The actuator lock in the ON position, locks the
actuator in the landing zone position. The lock
prevents the actuator from moving during shipping,
installation, or removal of the disk enclosure.
Back View
2.1.9 Actuator Position Indicator
When the edge of the actuator coil former is in
line with the IN edge of the indicator
a ,
the
actuator is at the inner stop and behind home.
When the edge of the actuator coil former is in
line with the middle of the I N tab
m ,
the actu-
ator is at home (track 0).
When the edge of the actuator coil former is in
line with the OUT edge of the indicator
iii,
the actuator is at the outer stop.
~~.-
' , '
I
FJ
B m' \
Actuator
Position
2.1.10 Circuitry Location
The disk drive circuitry is housed in two separate
areas. The cards and cables for the servo head out-
put preamplifier and for the data heads, write
driver, and read preamplifier are mounted on the
disk enclosure; they are not enclosed within the
sealed cover. The servo head output preamplifier is
mounted on the actuator. Part of the head selection
circuitry is mounted on the disk enclosure. The
remainder of the disk drive circuitry is mounted
on the 01 A2 board (I/O board).
Disk Enclosure
Actuator
Coil
DE Cards
and Cables
Pivot
Front View
Disk Drive
2-3
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