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ii
CD PLAYER ADJUSTMENT
PROCEDURES
(Continued)
DIFFRACTION GRID ADJUSTMENT
1.
2.
3.
4.
5.
6.
7.
Apply Power Switch to the set and press the STOP button.
Short test point TP2 (TEST) pinto the GND, and then ehort
)est terminal
(CN15) TOFF pin to GND to turn the tracking
servo OFF.
In this state, connect the E-beam output of test terminal
(CN15) to Channel 1 of the oscilloscope
and F-beam out-
put of test terminal
(CN15) to Channel 2, and now observe
the Iissajous waveform
on the oscilloscope.
Place the test
disc YEDS7 on the table load, and press the
PLAY button.
When the disc begins to rotate a waveform
will appear
on the oscilloscope.
While
observing
this waveform,
move the Linear
Motor in the direction
of the arrow
by
hand to send the pick-up to the outer edge.
ection of
k-up motion
When the pick-up approaches
the outer edge, the wave-
form on the oscilloscope
will suddenly
disappear,
and if
it is now pushed further
outwards
there will be points at
which waveforms
will appear again.
These locations
are
the multiburst
signal storage locations,
If the disc rotates
at high speed at this time, perform this step once again.
Set
the oscilloscope
to X-Y operation
to bring
up the
waveforms.
Insert the adjustment
tool in the diffraction
grating
adjustment
hole on the pick-up,
and rotate the
adjustment
tool to right and left. The waveform
should be
almost a straight
line with a phase difference
of 0° as
shown in Fig. 3 below. This indicates
that the beams are
arranged
in one straight
line.
The
waveform
in Fig. 4 in-
dicates
that the beams
are not arranged
along the same
stream.
Fig. 3
Fig. 4
—
NOTE:
It is important
to turn the adjustment
tool only a little at a
time. If It Is rotated too far, the beams will be pushed over
into neighboring
streams.
8.
9.
10.
Jig
Next, when the waveform
in Fig. 3 is obtained,
turn the
adjustment
tool clockwise
from that position at which the
waveform
in Fig. 3 appeared
and adjust
so that the
waveform
is a straight
line with a phase difference
of
180°. (See Fig. 5)
Fig. 5
Once the state indicated
by the waveform
in Fig. 5 is ob-
tained,
hold the STOP button down temporarily,
and re-
move the connection
between
test point TP2 (TEST) pin
and the GND as well as that between test terminal
(CN15)
TOFF pin and GND.
Next, press the PLAY button, and set the oscilloscope
in
the DUAL MODE so that both E and F outputs can be seen.
Set the DISPLAY TIME to 51JS.Now, adjustment
is com-
plete if the waveforms
shown below In Fig. 6 (Channel
1
trigger)
are obtained.
Approximately
~
E-beam waveform
~
F-beam waveform
Fig. 6
NOTE:
Diffraction
grating
adjustment
is performed
for a singie
pick-up, so if the following
checks are performed
adjust-
ment is unnecessary.
a,
PLAY the fourth item on the test disc (Modern
Wave
H CA35-1045, Toshiba-EMl),
turn the tracking
servo
OFF, and check that the waveform
is linear
with a
phase difference
of 180°.
b,
Next, apply
tracking
servo,
and if the waveforms
shown in Fig. 6 are obtained
then adjustment
Is un-
necessary.
9–
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