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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 of | Play does not start or track search is impossible.
adjustment
@ Measurement instru-
| Connect the oscilloscope to
@ Player state
Test mode, focus and spindle servos
ment connections
TPI, Pin 2(TRK. ERR). This
closed and tracking servo open
connection may be via a low
ass filter.
@ Adjustment location
| VR102 (TRK. BAL)
[Settings]
50 mV/division
5 ms/division
DC mode
[Procedure]
1. Move the pickup to midway across the disc (R=35 mm) with the MANUAL/TRACK
SEARCH FWD PP / Pl or
REV Iki / <i key.
:
3, Line up the bright line (ground) at the center of the oscilloscope screen and put the oscilloscope into DC mode.
4, Adjust VR102 (TRK. BAL.) so that the positive amplitude and negative amplitude of the tracking error signal at TP1,
Pin 2 (TRK. ERR) are the same (in other words, so that there is no DC component).
pO
When there is a DC
When there is no DC
component
component
36
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