Table of Contents
Advertisement
3. COARSE GRATING AND TRACKING (TRKG) BALANCE ADJUSTMENT
CLD-2710K
Mechanical Adjustment
@ Purpose: To adjust the laser beam which is divided into three by the grating to the optimum position on the track. Set the TRKG
servo offset voltage to ОУ.
4
€ When not properly adjusted: Disc playback will be impossible. During play, tracks may be skipped.
€ Measuring
instruments
| € Small screwdriver € Oscilloscope
and jigs:
@ Measuring point:
€ CN401 -9(TRKG ERR)
ӨТесі
disc
and
player | € 8-inch LD test disc GGV1003
mode
€ The carriage assembly should be in the forward st
@ Positions to be adjusted
Connection diagram
Oscilloscope
V:50mV/div
H:5mS/div
DC input
Not null point
Adjustment Procedure
<Coarse Grating Adjustment>
. Play the LD test disc.
. Search around for frame 86,500.
. Open the ТЕКС servo.
(See the table of operation in the test mode .)
. Connect
an
oscilloscope
to СМ401-9
and
observe
the
waveform.
. Coarse adjust the TRKG error waveform becomes maximum
by turning the TRKG and tangential direction angle adjustment
screw for the pickup adjustment. (This is indispensable in order
to minimize dispersion in the subsequent adjustments.)
. Insert the small screwdriver into the grating adjustment hole.
Turning the grating will allow you to vary the amplitude of the
TRKG error waveform. Find the position where the waveform
amplitude becomes minimum with a smooth envelope.(Fig. 2)
(This indicates that the 3- way split laser beams are directed
onto the track. This is called the null point.)
© Test Mode (86,500, ТЕКС servo : Open, Tilt servo : Neutral)
ate.
€ Grating € VR602(TRKG BAL)
Small screwdriver
Fig. 3 Maximize the TRKG error
Fig. 2 Null point
a=b
7. Slowly tum the grating counterclockwise from the on track
position until the waveform amplitude becomes maximum,
(Fig. 3)
8. Close the TRKG
servo and check that a normal picture is
displayed on the TV screen.
<TRKG Balance Adjustment>
1. Align the oscilloscope GND so that it comes to the center of
the oscilloscope screen.
2. Adjust VR602
so that the positive and negative amplitude of
the ТЕКС error waveform become equal. (Fig. 3)
Note : If adjustment of VR602 fails to disturb the tracking, perform
the adjustment after set VR607 to the mechanical center.
77
Advertisement
Table of Contents
