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PD-41,PD-9700
2. Grating adjustment
Symptom when out!
Play does not start, track search is impossible, tracks are skipped.
of adjustment
Measurement instru-| Connect the oscilloscope to TP 1, Pin|
@ Player state
Test mode, focus and spindle servos
mentconnections
| 2 (TRI ERR) via a low pass filter.
closed and tracking servo open.
(See Figure 2)
@ Adjustment location | Pickup grating adjustment slit
[Settings]
50 mV/division
5 ms/division
DC mode
[Procedure]
1. Move the pickup to midway across the disc(R=35 mm) with the TRACK FWD Di or REV EM key.
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. Ifyou 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.
Note : The amplitude of the tracking error signal is about 3 Vp-p (when a 39 k? + 0.001 yF low pass filter is used). If
this amplitude is extremely small (2 Vp-p or less), then 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.
'
5. Return the pickup to more or less midway across the disc with the TRACK REV WW key, press the PAUSE [4] key and
double check that the track number and elapsed time are displayed on the front panel. If they are not displayed at this
time or the elapsed time changes irregularly, double check the null point and adjust the grating again.
Figure 2
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