6.11.1
TEST
CONFIGURATION
(1)
Set oscilloscope
as
follows.
• Set vertical sensitivity of both channels to 0.2v per cm.
• Set channel select switch to the Chopped mode.
• Trigger internal from Channel 1 ; use positive trigger slope.
• For 1500 rpm disk drives, set the sweep at 0.5 msec per division; for
2400
rpm
disk drives, set the sweep at 0.2 msec per division.
(2)
Connect test probe ground clips to
TP15
on the Logic PCBA.
(3)
Connect Channel 1 test probe to
TP11
on
the Logic PCBA.
(4)
Connect Channel 2 test probe to
TPB
on the Logic PCBA.
(5)
Apply power to the disk drive. When the SAFE indicator becomes illuminated,
insert a disk cartridge. Depress the
RUN
I
STOP
switch once and allow the disk
drive to come Ready as indicated by the READY indicator being illuminated.
NOTE
A square wave
should
be observed on Channels 1
and
2
as
the
disk
drive comes
up
to speed.
6.11.2
TEST
PROCEDURE
(1)
Adjust Channel 1 trigger to display the low-to-high transition waveform. Adjust
the sweep rate
and
horizontal position controls to position the leading and trailing
edge of the waveform exactly
10
divisions apart. Refer to Figure 6-1B.
(2)
Observe the waveform on Channel
2.
The high-to-Iow transition should occur at
the center vertical graticule
line with :I:
1/2
of a major division. Refer to Figure6-1B.
NOTE
This relationship is
specified
for
an
ambient
[room]
temperature
of
23
:t:
5 degrees C [73.4
:t:
9 degrees F].
(3)
If the relationship established in Steps
(1)
and
(2)
is not correct, and the spindle
speed accuracy has
been
verified, perform the adjustment procedure detailed in
Paragraph
6.11
.3.
6.11.3 ADJUSTMENT
PROCEDURE
(1)
Adjust the Sector Phase-Lock-Loop centering potentiometer
R57
to position the
high-to-Iow transition
of
the waveform on Channel 2
(TPB)
to the center vertical
graticule
line.
(2)
Refer to Figure 6-1B for the correct positioning of the waveform
NOTE
This
adjustment
should
be made
at
a room temperature
of
23:t: 5 degrees C [73.4
:I:
9 degrees Fl.
630D
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