Pioneer PD-X940M Service Manual page 25

Step
No.
Setting
Oscilloscope
Test
Points
Adjusting
Points
Check items/
Adjustment
specifications
PoD-x9S40M
Adjustment procedure
0.5V/div 5 ms/div
TP!
Pin 2
TRK.ERR
Grating
Grating
Null point
Maximum
amplitude
Set to TEST mode. (See page 34.)
e Shift the pickup close to the center of the disc by
pressing MANUAL SEARCH FWD key (bt) so that
the grating adjustment screw of the pickup can be
seen through the oval hole of the upper side of the
servo mechanism.
* Insert a grating driver into the adjusting hole from the
upper side of the mechanism as shown in Fig. 9-2, and
confirm that the grating screw turns.
Press TRACK FWD key (Dt4) and PLAY key ( p> }
sequentially and close the focus servo and spindle
servo. (Do not close the tracking servo.)
Observe the waveform of pin 2 TRK.ERR (Tracking
error) of TP1 with an oscilloscope. At this point,
insert a 4 kHz cutoff low-pass filter. (Fig. 9-3)
* Turn a grating driver and find null point. (Photo. 9-1)
¢ Then, turn slowly the grating driver
counter clockwise from the null point and adjust at
the point where the waveform (Tracking error signal)
firstly becomes maximum amplitude. (See Photo. 9-3.)
Note:
If the grating driver is pressed strongly, the pickup
moves toward disc center, accordingly adjustment
becomes difficult.
* Finally, be sure to confirm that the tracking error
signal (at this time, 4 kHz of cutoff low-pass filter is
not inserted) when the pickup is moved toward the
disc center and the P-P voltage of the tracking error
signal at the outer circumference of the disc are not
varied greatly. When the level is deviated over
+10%, adjust again by turning grating screw to the
maximum error amplitude point.
37