Pioneer PDR-04 - Manual (Page 53)

PDR-04
6.2.4 Coarse Grating Adjustment Adjustment 1
• Objective
• Symptom when out
of adjustment
To align the tracking error generation laser beam spots to the optimum angle on the track.
Play does not start, track search is impossible, tracks are skipped.
• Measurement instru­
ment connections
Connect the oscilloscope to
CN104 (TP1), Pln3(TE)
This connection may be via a low
pass filter. (See Fig. 3)
[ Settings ]
50 mV/div.
5 mS/div.
DC mode
Player state
• Adjustment
location
Disc
Test mode,focus and spindle servos
closed and tracking servo open.
Grating slit on pickup
STD-903
[Procedure]
(1) Move the pickup to the position where the grating adjustment slit will be seen with the MANUAL / TRACK SEARCH FWD
►► or REV ◄◄ keys so that the grating adjustment can be adjusted.
(2) Press the FINALIZE key, then the PLAY ► key in that order to close the focus servo then spindle servo.
(3) Insert a screwdriver into the grating adjustment slit and adjust the grating to find the null point.
For more details, see 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 counterclockwise
from the null point and set the grating to the first point where the wave amplitude reaches its maximum.
Reference : Fig. 4 shows the relation between the angle of the tracking beam with the track and the waveform.
(5) Return the pickup to more or less midway across disc with the MANUAL / TRACK SEARCH ◄◄ key, press the
PAUSE
II
key and 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, check the null point and adjust the grating again.
Small
screwdriver
Fig.3
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