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PD-S601
7. 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 7.
@ Player state
Test mode, play
ment connections
SO mV/division
20 mV/division
)
"
~7
Sy node
@ Disc
YEDS
{Procedure]
1. Set the AF generator output to 1.2kHz and 2 Vp-p.
2. Press the MANUAL SEARCH FWD D> or REV <i] key to move the pickup to halfway across the disc (R=35 mm),
(10:1)
Pin 3 (TRK. IN)
a
Pin 4 (GND)
Pin 2 (TRK. ERR)
Tracking Gain Adjustment
Higher gain
Optimum gain
38
PD-S601
8. Focus Error Signal (Focus S Curve) Verification
To judge whether the pickup is ok or not by observing the focus error signal. The pickup is
judged from the amplitude of the tracking error signal (as discussed in the section on adjusting
the tracking error balance) and the waveform for the focus error signal.
@ Symptom when out of
adjustment
Measurement instru-
| Connect the oscilloscope to
@ Player state
Test mode, stop
ment connections
TPI, Pin 6 (FCS. ERR).
5 ms/division
i
YEDS-7
DC mode
@ Disc
(Procedure]
1. Connect TP! Pin 5 to ground.
2. Mount the disc.
3. While watching the oscilloscope screen, press the PROGRAM key and observe the waveform in Figure 8 for a
moment. Verify that the amplitude is at least 2.5 Vp- p and that the positive and negative amplitude are about equal.
Since the waveform is only output for a moment when the PROGRAM key is pressed, press this key over and over
until you have checked the waveform.
A
A=B
A+B 2 2.5Vp-p
8
[Judging the pickup]
Do not judge the pickup until all the adjustments have been made correctly. In the following. cases, there may be
something wrong with the pickup.
1. The tracking error signal amplitude is extremely small (less than 2 Vp-p).
2. The focus error signal amplitude is extremely small (less than 2.5 Vp-p).
3. The positive and negative amplitudes of the focus error signal are extremely asymmetrical (2: 1 ratio or more).
4. The RF signal is too small (less than 0.8 Vp-p) and even if VRI (laser power) is adjusted , the RF signal can not be
brought up to the standard level.
33
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