6300
6.8.1.3 Adjustment Procedure
(1)
Adjust potentiometer
R69
(X
+ 0 Gain) to attain a 12v peak-to-peak sine wave at
TP20
on the oscilloscope screen while the positioner carriage is being slowly
moved back and forth through its full stroke by hand.
NOTE
Clockwise rotation
of
R69
will
increase amplitude.
(2)
If the 12v peak-to-peak sine
wave
cannot
be
attained, perform the signal polarity
and quadrature checks in Paragraph 6.8.3.
(3)
Adjust potentiometer
R70
(X
+ 0 Balance) to center the waveform equally about
ground.
(4) Perform the X +
90
Gain and Balance procedure detailed in Paragraph 6.8.2.
6.8.1.4
Scale-Flatness Adjustment
(1)
Loosen the three Allen-head screws that hold the scale assembly to the side
of
the
carriage. The
scale
will
pivot Slightly around its locating pin.
(2)
Manually move the positioner carriage back and forth slowly (at a constant rate)
through its
full stroke while monitoring the waveform at
TP20
(X +
0)
(refer
to
Figure 6-4).
(3)
Adjust the horizontal angle of the scale so that the amplitude
of
the waveform at
TP20
remains constant throughout each full stroke of the positioner carriage.
(4)
Tighten the three Allen-head screws loosened in Step (1).
(5) Perform the X + 0 Gain and Balance adjustment procedure detailed
in
Paragraph 6.8.1 .3.
6.8.2
X +
90
GAIN AND BALANCE
The
X + 0 Gain and Balance checks and adjustments in Paragraph 6.8.1 must be performed
before the
X +
90
Gain and Balance tests. Values given
are
for all versions
of
the 03000
with values for
200
tpi models parenthetically stated.
6.8.2.1 Test Configuration
(1) Prepare the positioner and oscilloscope as described in Paragraph 6.7.1.
(2)
(200
tpi Only). Install a jumper between
TP1
on the Servo PCBA and
TP4
on the
Temperature And Write Compensation PCBA.
(3)
(200
tpi Only). Remove connector J215 from the Servo PCBA.
(4)
Connect oscilloscope Channel 1
X10
test probe to
TP2.
Connect ground lead
to
TP1.
(5)
Set oscilloscope Channel 1 sensitivity to
O.2v
per division.
(6)
Set horizontal sweep rate to 2
iJ.sec
per division.
(7)
Set oscilloscope trigger control to Line and Auto.
(8)
Manually load the heads
onto
the disk.
NOTE
A
ground
reference sweep trace is
obtained
by
centering
the trace on
a
particular
graticule
line
with
the vertical
input
mode
switch
of
the
oscilloscope
set
to
ground
pOSition.
6-18
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