Pdr-04, I....j – Pioneer PDR-04 User Manual

Page 70

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PDR-04

6.3.20 Focus Servo Loop Gain Adjustment

Adjustment 2

• Objective

• Symptom when out

of adjustment

To optimize the focus servo loop gain.

Playback does not start or focus acutuator noisy.

• Measurement instru

ment connections

See Fig.6.

(SERVO UCOM BOARD assy)

[ Settings ]
CH1 : 0.1 V/div. X-Y mode
CH2-.10 mV/div.

• Player state

• Adjustment

location

• Disc

Test mode, play

VR201 (PCS. GAIN)

(SERVO UCOM BOARD assy)

STD-903

[ Procedure ]

(1) Set the AF generator output to 1.4kHz and 1 Vp-p.

(2) Move the pickup to midway across the disc (R = 35mm) with the MANUAL / TRACK SEARCH FWD ►► or REV

◄◄ keys.

(3) Press the FINALIZE key, the PLAY ► key, then the PAUSE

key in that order to close the respective servos and put

the player Into play mode.

(4) Adjust VR201 (FCS. GAIN) so that the llssajous waveform is symmetrical about X axis and the Y axis.

CN204

Fig. 6

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= I i :

-t-i ..... r-i-i-fi---:

:...r

■¿•t...i.... r-1......i

■

... j...;

... r-r-

;... -i---

! i

.... i...i-

...^...: -

•••r..;... :

: ;■ -r—i

i ! i ................. i-—i

J«

__ I....j

..I..j...f...I..i... }...

i i i i i M

: i

i..... r-1....1 ^... ;....i.... i....i.....

Higher gain

Optimum gain

i ...J

1.!.

......

,±i:

Lower gain