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7. Tracking servo loop gain adjustment
© Objective
To optimize the tracking servo loop gain
e Symptom when out | Playback does not start, during searches the actuator is noisy, or tracks are skipped.
of adjustment
@ Measurement instru- | See Figure 7.
@ Player state
Normal mode, play
ment connections
[Settings]
© Adjustment location | VR151 (TRK GAN)
CH1
CH2
50 mV/division
5 mV/division
X-Y mode
[Procedure]
1.
Set the AF generator output to 1.2 kHz and 2 Vp-p.
2.
Press the MANUAL SEARCH FWD Pb or « key to move the pickup to halfway across the disc (R = 35 mm), then
press the TRACK FWD Pi key, the PLAY [> key, then the PAUSE [1] key in that order to close the corresponding
servos and put the player into play mode.
3.
Adjust VR151 (TRK GAN) so that the Lissajous wave form is symmetrical about the X axis and the Y axis.
3PIN
-(TRK IN)
4PIN
(GND)
PIN
[9] (10:1)
(TRK ERR)
130K Q
'
bezseoees 0.001 4 F |
Low pass filter
Figure 7
Tracking Gain Adjustment
Optimum gain
Minimum gain
16
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