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1.
Set up the oscilloscope
Channel A:
Test Point 4
Channel
B:
Test Point 5
Ground:
Test Point 8 Or 14
Read Differentially:
A plus B, B inverted
Time Base:
20 milliseconds per division
External Trigger:
Test Point 12
2.
Apply power to the drive.
3.
Select the drive.
4.
Insert an alignment diskette.
5.
Loosen Number 1 Phillips screw at rear of Track 0 sensor.
Track 0 stop block slides inside of
Tra~k
0 sensor.
See
Figure 5-13.
6.
Step the carriage to Track 0, and observe the waveform.
7.
Slowly push the Track 0 stop block into Track 0 sensor until
the output amplitude begins to decrease on the oscilloscope.
8.
Slowly retract the Track 0 stop block until amplitude stops
increasing.
Retract it an additional 1/32 of an inch.
Tighten the Track 0 stop block screw.
5.11
HEAD OUTPUT CHECK
The
head
output check measures the head's output amplitude relative
to
the
diskette
being
used.
When using certified, quality media,
typical
values
will
be
200
millivolts
peak-to-peak
or greater.
However, values may be significantly less, 100 millivolts peak-to-peak
typical,
if inferior or defective media is used, and does not indicate
a faulty head.
Head
amplitude
can
be
verified
by establishing a nominal value of
amplitude
for
the
diskette on a known working drive.
In all cases,
amplitudes greater than 200 millivolts peak-to-peak are acceptable.
5-17
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