Grating Adjustment - Pioneer CJ-V55 Service Manual

CJ-V55
Oscilloscope Setting
Check items/
Adjustment
specifications
Adjustment procedure
GRATING ADJUSTMENT
i Set to Service mode.
i Shift the pickup close to the center of the disc by
pressing l-MULTTSPEED+l key + H] so that the
grating adjustment screw of the pickup can be s
through, the oval hole of the upper side of the servo
mechanism.
> Insert the © screwdriver into the adjusting hole from
the upper side of the mechanism as shown in Fig.
7-7, and confirm that the grating screw turns.
» Press I - MULTI-SPEED+1 ^ key + E and
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 4kHz cutoff low-pass filter. (Fig. 7-8)
Pin 2 (TRK. ERR)
0.5V/div 5msec
/div
TP1
Pin 2
(TRK. ERR)
Grating Null point • Turn the © screwdriver and find null point.
(Photo. 7-1)
Maximum • Then, turn slowly the © screwdriver counterclockwise
amplitude from the null point and adjust at the point where
the waveform (Tracking error signal) firstly becomes
maximum amplitude. (See Photo. 7-2.)
Note:
If the © screwdriver 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 liot'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.
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