Focus/Tracking Gain Adjustment1. Place the optical pick-up level, horizontally. (If the optical pick-
A servo analyzer is necessary in order to perform this adjustmentup is not level, the 2-axis device will be weighted and adjust-
exactly.ment cannot be done.)
However, this gain has a margin, so even if it is slightly of2. Connect the oscilloscope between IC501 f, there0 pin (TEO) and #1
is no problem. Therefore, do not perform this adjustment.pin (VC) on the MAIN board.
3. Set the disc (YEDS-18) and Press the ^ (+) key.
Focus/tracking gain determines the pick-up follow-up relative to4. Turn RV502 slightly clockwise (tracking gain drops) and obtain
mechanical noise and mechanical shock when the 2-axis devicea waveform with a fundamental wave (waveform has large
operate. However, as these reciprocate, the adjustment is at the pointwaves) as in Figure 1 .
where both are satisfied.5. Turn RV502 slowly counterclockwise (tracking gain rises) until
Y When gain is raised, the noise when 2-axis device operates in-the fundamental wave disappears (no large waves) as in Figure
creases.2.
Y When gain is lowered, it is more susceptible to mechanical shock6. Set RV502 to the position about 30 !counterclockwise from the
and skipping occurs more easily.position obtained in step 5. If RV502 contact point is more than
This adjustment has to be performed upon replacing any of the fol-90 ! counterclockwise from mechanical center, tracking gain is
lowing parts :too high. In this case, readjust from step 4.
Y Optical pick-up7. Press ^ (+) or = keys and observe the 100 track jump
Y RV503 (Focus gain)waveform. Check that no traverse waveform appears for both
Y RV502 (Tracking gain)^ (+) or = directions. (See Figures 3 and 4.) It is ac-
Normally, be sure not to move RV503 (focus gain) and Rceptable if the traverse waveform appears only now and then,V502
(tracking gain).but if it appears constantly raise tracking gain slightly and check
step 7 again.
� Focus Gain Adjustment � 8. Check that there is no abnormal amount of operation noise (white
Procedure :noise) from the 2-axis device. If there is, tracking gain is too
This adjustment is not performed. If focus gain RV503 is turned,high, readjust starting with step 4.
set to mechanical center
The waveforms are those measured with the oscilloscope set as
� Tracking Gain Adjustment �shown below.
(perform at normal operation)Y VOLT/DIV : 50mV
Y TIME/DIV : 5mS
[MAIN BOARD] (Side B)Y Waveform when tracking gain lowered.
Fundamental wave appears (large waves).
oscilloscope
0V(DC range)
Fig. 1IC501 0 pin
Y Waveform when fundamental wave disappears (no large waves).(TEO)
IC501 #1 pin
0V(VC)
Fig. 2
Y Waveform when no traverse waveform during 100 track jump.
(Brake application is smooth because of adjustment.)
10
0V
Fig. 3
100 track jump waveform
Y Waveform when no traverse waveform during 100 track jump.
(Brake application is poor because of adjustment.)
0V
100 track jump
waveformtraverse waveform
Fig. 4
� 9 � |
ACEC
