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3. Tracking error balance adjustment
© Objective
To correct for the variation in the sensitivity of the tracking photodiode
© Symptom when out | Play does not start or track search is impossible
of adjustment
© Measurement instru- | Connect the oscilloscope to TP1, Pin |e Player state
Test mode, focus and spindle servos
Ment connections
2 (TRK ERR). This connection may
closed and tracking servo open
be via a low pass filter.
[Settings]
50 mV/division
@ Adjustment location | VR102 (TRK BAL)
5 ms/division
DC mode
[Procedure]
Move the pickup to midway across the disc (R = 35 mm) with the MANUAL SEARCH FWD
pp or « key.
Press the TRACK FWD Pi key, then the PLAY [> key in that order to close the focus servo then the spindle servo.
Line up the bright line (ground) at the center of the oscilloscope screen and put the oscilloscope into DC mode.
Adjust VR102 (TRK BAL) so that the positive amplitude and negative amplitude of the tracking error signal at TP]
Pin 2 (TRK ERR) are the same (in other words, so that there is no DC component).
-
A#B
a
A=B
GND =>
GND
B
B
|;
4
When there is a DC
When there is no DC
component
component
11
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