(13)
Position the receiver post so that the reticle-to-scale gap is approximately
0.127 mm (0.005-inch).
(14)
Partially tighten the Allen-head screws loosened in Step (12).
(15)
Withdraw the mylar shim to the pOint where the SAFE light becomes illuminated.
The
shim
can
be
left in this partially withdrawn position.
(16)
Depress and release the RUNISTOP switch. Manually advance the carriage about
one inch from its fully retracted position.
The
disk drive will come up to speed
after
57
seconds
and
the
READY
indicator will
be
illuminated.
NOTE
The
READY
light
may be delayed 3
or
6 minutes,
depending on the options installed in the disk drive.
(17)
On
top load disk drive models, verify that the cleaning brushes make from 2 to 4
complete sweeps across the platters.
(18) Manually load the head onto the disk and check the reticle-to-scale gap, with the
mylar shim,
as
the positioner carriage is manually moved through its full forward
and
return strokes.
NOTE
Perform Steps [19] through [21]
only
if
the retic/e-to-sca/e
gap throughout the length
of
the scale
Is
not
approxi-
mately 0.127 mm
[O.OOS-inch]
when using the mylar shim.
(19)
Loosen the three Allen-head screws that hold the scale
to
the side
of
the carriage.
The scale will pivot
Slightly around 'its locating pin. Position the angle of the scale
so that the reticie-to-gap remains approximately 0.127 mm (0.005-inch)
as the
positioner carriage travels through
Its
full
forward and return strokes.
(20)
Partially tighten the Allen-head screws loosened in Step (19).
(21)
Remove the mylar shim.
Note
The
foregoing reticle-to-scale gap adjustments are
preliminary. Additional adiustments will
be
required
during static positioner adiustment [Paragraph 6.8].
6.7.1.1
Initial Potentiometer Settings, Servo PCBA
The
following procedure defines the initial setting of potentiometers located on the Servo
PCBA. It is important to note that the initial potentiometer settings are required only when
the
Servo PCBA, Positioner, Position Transducer,
or
Velocity Transducer
have
been
replaced, or when repairs
have
been
made (I.e., parts replaced) in the 10v power supplies
or the Positioner
Servo circuit.
(1) Velocity Feedback Potentiometer. Rotate potentiometer
R55
fully CCW, then
adjust 7
turns.in the
CW
direction.
(2) Current Feedback Potentiomter. Adjust potentiometer
R111
to
the center of its
range, i.e., approximately 10 turns from
full
CCWorCW
position.
(3)
X + 0 Offset Potentiometer. Adjust potentiometer
R22
to the center
of
its range,
i.e., approximately
10
turns from full
CCW
or
CW
position.
(4) Velocity Offset Potentiometer. Adjust potentiometer
R204
to the center of its
range, i.e., approximately
10
turns from full
CCW
or
CW
position.
6-15
8300
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