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PD-41,
PD-93700
6. Focus servo loop gain adjustment
@ Objective
To optimize the focus servo loop gain
@ Symptom when out|
Playback does not start or focus actuator noisy
ofadjustment
@ Measurement instru-
See Figure 6.
@ Player state
Test mode, play
ment connections
[Settings]
CH 1
CH 2
@ Adjustment location | VR 152 (FCS GAN)
20 mV/division
5 mV/division
X-Y mode
[Procedure]
1. Set the AF generator output to 1.2 kHz and 1 Vp-p.
2. Press the TRACK FWD Dior REV kX key to move the pickup to halfway across the disc (R = 35 mm), then press the
OUTPUT key, the PLAY > key, then the PAUSE |) key in that order to close the corresponding servos and put the
player into play mode.
3. Adjust VR 152 (FCS GAN) so that the Lissajous wave form is symmetrical about the X axis and the Y axis.
(FCS IN)
4PIN
(GND)
Figure 6
Focus Gain Adjustment
Higher gain
Optimum gain
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