Pioneer PD-M423 Service Manual - Page 22

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Also for Pioneer PD-M423: Operating Instructions Manual (16 pages)

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PD-M423, PD-M403

5. Focus Servo Loop Gain Adjustment

@ Objective

To optimize the focus servo loop gain.

@ Symptom when out of | Playback does not start or focus actuator noisy.

adjustment

[Procedure]

1. Set the AF generator output to 1.2 kHz and 1 Vp-p.

2. Press the TRACK /MANUAL SEARCH FWDPo> .- DP] or REV KK. <ki key to move the pickup to halfway across

the disc (R=35 mm), then press the PGM(PROGRAM) key, the PLAY/PAUSE [> / [ll] key twice in that order to

close the corresponding servos and put the player into play mode.

3. Adjust VR152 (FCS. GAN) so that the Lissajous waveform is symmetrical about the X axis and the Y axis.

Focus Gain Adjustment

Higher gain

Optimum gain

Lower gain