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PD-S601
PD-S601
@ Objective
To align the tracking error generation laser beam spots to the optimum angle on the track.
When you insert the regular screwdriver into the slit for the grating adjustment and change the grating angle, the
amplitude of the tracking error signal at TP1, Pin 2 changes. Within the range for the grating, there are five or six
locations where the amplitude of the wave reaches a minimum. Of these five or six locations, there is only one at which
the envelope of the waveform is smooth. This location is where the three laser beams divided by the grating are all nght
above the same track. (See Figure 3.)
This point is called the null point. When adjusting the grating, this null point is found and used as the reference position.
Tuming the grating counterclockwise
Tuming the grating clockwise —
0%
0
%
07
0
%
0
%
o
Wavetorm of TP1, Pin 2
Watt I) sm wf
|
wie
\
7
Grating adjustment position
@Symptom when out of | Play does not start, track search is impossible, tracks are skipped.
adjustment
@Measurementinstru-
| Connect the oscilloscope to
@ Player state
Test mode, focus and spindle servos
ment connections
TPI, Pin
2(TRK. ERR)viaa
closed and tracking servo open
low pass filter.
@ Adjustment location
| Pickup grating adjustment slit
(See Figure 2)
Fi
er
@ Disc
12- cm disc.
[Settings]
oe
(YEDS-7 can not be used.)
i
Ht
DC mode
[Procedure]
1. Move the pickup to the outer edge of the disc with the MANUAL SEARCH FWD DD or REV <kikey.
2. Press the PROGRAM key, then the PLAY > key in that order to close the focus servo then the spindle servo.
3. Insert an ordinary screwdriver into the grating adjustment slit and adjust the grating to find the null point. For more
details, see the next page.
4. If you slowly turn the screwdriver clockwise from the null point, the amplitude of the wave gradually increases,
then if you continue turning the screwdriver, the amplitude of the wave becomes smaller again. Turn the
screwdriver clockwise from the null point and set the grating to the first point where the wave amplitude
reaches its maximum.
Reference : Figure 3 shows the relation between the angle of the tracking beam with the track and the waveform.
Null point
Figure 3
Note
: The amplitude of the tracking error signal is about 3 Vp-p (when a 39 kQ+ 0.001 u F low pass filter is
used). If this amplitude is extremely small (2 Vp-p or less), the objective lens or the pickup malfunction
may be the cause. If the difference between the amplitude of the error signal at the innermost edge and
outermost edge of the disc is more than 10%, the grating is not adjusted to the optimum point, so adjust it
again.
. Return the pickup to more or less midway across the disc with the MANUAL SEARCH REV <k key, press the
PAUSE itt key and double check that the track number and elapsed time are displayed on the front panel. If they are
Maximum amplitude
Waveform other than the
not displayed at this time or the elapsed time changes irregularly, double check the nul! point and adjust the grating
again.
Grating
adjustment
Adjustment locations
32
33
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