6.9.3.3 Adjustment Procedure
(1)
Insert a screwdriver blade into the
slot
at the top of the receiver post and adjust
the reticle so that the waveform observed at
TP20
is positioned with its crossover
point (Figure 6-9 (A)) at ground.
(2)
Observe the amplitude of the waveform at
TP20
(Figure 6-6).
(3)
Acceptable limits:
•
13.2v (maximum)
• 10.8v (minimum)
(4) If the acceptable
limits
are not met, adjust
R69
to
obtain a 12v peak-to-peak
envelope at
TP20.
(5)
Check that the waveform at
TP20
is balanced about ground as shown in Figure
6-6.
(6)
If the waveform at
TP20
is not balanced about ground, adjust
R70
until the
observed waveform is balanced about ground.
(7)
Check that the start
of
the waveform at
TP20
is symmetrical about ground as
shown in Figure 6-6.
(8)
If the waveform is not symmetrical about ground, adjust
R22
so that the start of
the waveform viewed at
TP20
is symmetrical about ground.
(9)
Select Channel 2 and check that the start of the waveform at
TP16
is symmetrical
about ground.
(10) If the start of the waveform (as shown in Figure 6-7) is not symmetrical, adjust
R204
to obtain the correct waveform.
(11)
Tighten the hex-head screw loosened in Paragraph 6.9.3.2, Step (3). Check the
waveform at
TP20
to ensure that tightening the hex-head screw has
not
disturbed
or altered the crossover point.
6.9.4
CURRENT ADJUSTMENT
Values are given for all versions
of
the 03000 with values
for
200
tpi models parenthetically
stated. .
The following current adjustment procedure is made to ensure that the
pOSitioner carriage
will perform a 67-track seek within
an
average time interval of
35
msec (or 134-track seek
within
an
average time interval
of
38
msec for
200
tpi models).
6.9.4.1 Test Configuration
(1)
Prepare the positioner
as
described in Paragraph 6.9.1.
(2)
Set the oscilloscope
as
follows.
• Set the Channel 1 sensitivity to 0.02v per division.
• Set the sweep rate to 1 msec per division.
• Connect Channel 1
X10
test probe to TP15.
(3)
Set the disk exerciser to produce a 67-track (134-track for
200
tpi) repetitive seek
from cylinder
000
to cylinder
067
(134 for
200
tpi).
(4)
Set the
disk
exerciser to
ON
mode.
6-31
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