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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