Pioneer PD-41 Service Manual - Page 33

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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