1.5.1 Controls and Indicators
The controls and indicators (Figure 1-2) required for
normal
operation
are located
on
the
front
of
the drive
cabinet. Table 1-2 describes
the
function
of
each control
or
indicator.
1.5.2 Spindle
and
Drive
The spindle and drive system (Figure 1-3)
is
composed
of
the
spindle, spindle drive
motor,
and
the
recording disk. A
50/60
Hz, split-phase ac
motor
transfers
torque
(via
the
drive belt)
to
the
spindle drive pulley. Belt tension
is
maintained by a tension spring anchored
to
the
baseplate.
The spindle speed
is
electronically tested by a circuit
that
measures
the
INDEX PULSE interval. When
the
interval
increases
to
approximately 45 ms, indicating an unsafe
speed,
the
drive
is
cycled down.
If
the
RUN/LOAD switch
is
placed in
the
LOAD position, ac power
is
rerr.oved from
the
motor
and
the
spindle coasts
to
a halt.
1.5.3 Linear Positioner
The linear positioner (Figure
I-I)
consists
of
the
linear
motor,
the
carriage,
the
read/write heads, and
the
linear
positioner transducer. To move
the
read/write heads across
the
recording disk, dc current
is
applied
to
the
bobbin-wound armature (Figure
14)
of
the
linear motor.
The resulting magnetic field reacts with a permanent
magnet in
the
motor
housing to either pull
the
armature
into
or
force it
out
of
the
permanent magnetic field,
depending
upon
the
polarity
of
the
current applied
to
the
armature. This
motion
is
transferred to
the
carriage, which
is
fastened
to
the armature.
As
a result,
the
read/write
heads, which are
attached
to
the
carriage, move across
the
surface
of
the
disk.
Any carriage movement
is
detected
by
the
linear positioner
transducer, which
is
located on
the
underside
of
the
carriage. The transducer
output
is
used with
the
control
logic
to
determine
the
cylinder position
of
the heads, and in
the
servo logic
to
govern
the
speed
of
carriage travel.
1.5.4 Cartridge-Handling System
The cartridge-handling system (Figure I-Sa) consists
of
a
cartridge receiver,
two
receiver lifting cams, an access
door
opener, a duckbill, and
two
cartridge support posts. During
normal
operation,
the
plastic cartridge
is
located only
by
the duckbill and support posts. The cartridge receiver
merely guides
the
cartridge
into
position
to
be picked
up
by
the
duckbill and
support
posts, allowing
the
recording disk
to
rotate
freely
on
the
spindle. The rotating spindle drives
the
disk by magnetic coupling
at
the
disk hub.
As
the
drive
front
door
is
opened,
the
lifting cams
rotate
to
elevate
the
receiver
to
a slanted position and
the
magnetic
coupling
at
the
disk
hub
is released. When
the
disk cartridge
is
inserted
into
the
receiver (Figure 1-5b),
the
access
door
opener
contacts
the
rear
of
the
top
cover, opening
the
access
door
to
allow
entry
of
the
read/write heads.
14
As
the
drive front
door
is
closed,
th
e cartridge is lowered
to
the
op
erating position, and
the
magnetic coupling again
engages the disk hub. When
the
cartridge
is
in
the
operating
position,
the
plastic case depresses the cartridge-on switch
and removes
the
no-cartridge interlock
condition
. The
cartridge receiver should
not
hold
the
cartridge tightly.
1.5.5 Logic Assembly
The logic assembly (Figure
I-I),
located in
the
right rear
portion
of
the
disk drive, holds eight printed circuit cards.
Three
of
these cards contain
the
system logic and
the
read/write circuits. Two cards contain
the
positioner servo
logic. One card is
the
cable
connector
that
interfaces
the
electronics with
the
positioner and
other
chassis-mounted
components, while
the
remaining
two
cards contain
the
interface cables and terminators.
1.5.6 Air System
The air system (Figure 1-6) consists
of
the
prefilter, blower,
absolute filter, plenum chamber, and
the
cartridge air
duct.
As
the
blower rotates, unfiltered air
is
drawn
through
the
prefilter, where it
is
purged
of
large dust particles. The
prefiltered air
is
then
circulated
through
the
logic assembly
and
into
the
plenum.
From
there,
the
air passes
through
the
absolute filter (where minute
contamination
is removed),
up
the
cartridge air
duct,
and
into
the
disk cartridge.
Cooling air
from
the
absolute filter
is
also shunted,
by
the
plenum,
through
the
linear positioner. Exhaust air exits
through
the
front
grill
of
the
drive.
1.5.7 Power Supply
The power supply (Figure
I-I),
located in
the
left rear
portion
of
the
disk drive, furnishes all
the
dc voltages for
the
drive. The power supply can operate
with
a
liS
V
or
230V, 50 or 60
Hz
line voltage
input
.
1.5.8 Read/Write Heads
There are
two
ramp-loaded read/write heads in
the
RK05
Disk Drive. One head functions
on
the
top
surface
of
the
recording disk and
the
other
on
the
bottom.
The heads are
mounted'
on
suspension arms
that
rest, when
the
heads are
unloaded, on a plastic cam block
of
the
duckbill (Figure
1-7). Flat cantilever springs connect
the
suspension arms
to
the
head-support tailpieces. When
the
drive is placed in
the
RUN mode,
the
positioner moves
the
heads forward
toward
cylinder zero. When the entire head slider pad has passed
the
edge
of
the
disk, a ramp
on
the
suspension arm slides
down
the
edge
of
the
plastic cam block,
thereby
moving
(loading)
the
heads close
to
the
disk surface. When loaded,
the
heads
"fly"
80
to
100 microinches from
the
disk
surface (Figure 1-8). A film
of
air (air bearing) between
the
disk and
the
head acts as a force away from
the
disk, while
the
cantilever spring is a counterbalancing force toward
the
disk. Thus, as long as
the
disk
rotation
remains
constant
the
heads remain
at
a relatively
constant
distance away from
the
disk surface.
