6300
6.8.5.4
Adjustment
Procedure
In the event that the voltage
transitions
do
not
occur
according
to
the tests performed in
Paragraph 6.8.5.2 and 6.8.5.3, repeat the test and
adjustment
procedures detailed in
Paragraphs 6.7 through 6.8.5.4.
6.8.6
VELOCITY TRANSDUCER PHASING
This test
will
establish
if
the
connections
to the velocity transducer are
correctly
phased.
6.8.6.1 Test
Configuration
(1)
Prepare the
positioner
as described in Paragraph 6.7.1.
(2) Connect Channel 1
test
probe to TP16.
(3)
Set Channel 1 gain
to
0.02v per division. Ensure that the polarity
switch
is set
to
the positive
position.
(4) Position Channel 1 ground-referenced sweep trace
to
the
center line
of
graticule.
(5)
Set sweep rate
to
20
msec per division.
(6)
Use
automatic
sync mode
and·
internal trigger.
6.8.6.2 Test Procedure
(1)
Manually move the
positioner
carriage such that the heads remain loaded and do
not come closer than one inch from the end
of
the platter.
(2)
Select Channel 1 .
(3)
Monitor
signals at TP16. Check
that
the waveform at TP16 goes negative
with
respect
to
ground when
the
positioner
carriage is moved forward toward the
spindle.
(4) Return the
positioner
carriage
to
its
fully
retracted
position.
NOTE
If
the waveform
at
TP16
does
not
meet the
conditions
in
Step [3], perform the
adjustment
procedure in Paragraph
6.8.6.3.
(5) Perform the Positioner Voice Coil Polarity procedure contained in Paragraph 6.8.7.
6.8.6.3
Adjustment
Procedure
If the waveform observed in Step (3)
of
Paragraph 6.8.6.2 at TP16 goes positive
with
respect to ground when the
positioner
carriage is moved toward the spindle, proceed as
follows.
(1)
Perform the Power-Down procedure detailed in Paragraph 6.8.8.
(2)
Reverse the wiring
to
pins
49
and 9 on connector J203 on the Servo PCBA.
(3)
Repeat the test procedure contained in Paragraph 6.8.6.2.
6-24
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