Pioneer PD-M423 Service Manual - Page 23

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PD-M423, PD-M403

6. Tracking Servo Loop Gain Adjustment

@ Objective

To optimize the tracking servo loop gain.

@ Symptom when out of {| Playback does not start, during searches the actuator is noisy, or tracks are skipped.

adjustment

@Measurementinstru-

| See Figure S.

@ Player state

Test mode, play

ment connections

50 mV/division

20 mV/division

YEDS-7

X-Y

mode

@ Disc

[Procedure]

1. Set the AF generator output to 1.2 kHz and 2 Vp-p.

2. Press the TRACK/MANUAL SEARCH FWD PtP - D>] or REV KK-

<kj key to move the pickup to halfway

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

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

3. Adjust VR151 (TRK. GAN) so that the Lissajous waveform is symmetrical about the X axis and the Y axis.

(10:1)

0.001 pF

accenceneeenereescanceceeneeres 2

Low pass filter

Tracking Gain Adjustment

Higher gain

Optimum gain

Lower gain