Pioneer PDR-04 - Manual (Page 70)

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
II
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
? i : i i i : = 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.!.
...... r
,±i:
i
Lower gain
70