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6-2. ELECTRICAL ADJUSTMENT
Note:
1.
CD Block is basically designed to operate without adjustment.
Therefore, check each item in order given.
2.
Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
3.
Use an oscilloscope with more than 10M impedance.
4.
Clean the object lens by an applicator with neutral detergent
when the signal level is low than specified value with the
following checks.
S-Curve Check
BD board
TP (FE1)
TP (VC)
Procedure :
1.
Chuck the disc (YEDS-18) beforehand, and disconnect the
power cord from the outlet.
2.
Connect oscilloscope to test point TP (FE1) on BD board.
3.
Connect test point (ADJ) on MAIN board to ground with lead
wire.
4.
The ADJ mode is set when the power cord is inserted into the
outlet and power is supplied.
5.
The fifth track is played automatically.
6.
Press the CHECK button.
7.
Check the oscilloscope waveform (S-curve) is symmetrical
between A and B. And confirm peak to peak level within 3±1
Vp-p.
S-curve waveform
Pressing the 1/u button stops the output of the waveform (s
8.
curve).
9.
After check, remove the lead wire connected in step 3.
Note : • Try to measure several times to make sure than the ratio of
A : B or B : A is more than 10 : 7.
• Take sweep time as long as possible and light up the
brightness to obtain best waveform.
Adjustment Location: BD board (See page 19)
RF Level Check
BD board
TP (RF)
TP (VC)
Procedure :
1.
Connect oscilloscope to test point TP (RF) on BD board.
2.
Turn Power switch on.
3.
Put disc (YEDS-18) in to play the number five track.
4.
Confirm that oscilloscope waveform is clear and check RF
signal level is correct or not.
18
Oscilloscope
Symmetry
A
Within 3
1 Vp-p
B
Oscilloscope
Note: A clear RF signal waveform means that the shape " " can be
clearly distinguished at the center of the waveform.
RF signal waveform
Adjustment Location: BD board (See page 19)
E-F Balance Check
BD board
TP (TE)
TP (VC)
Procedure :
1.
Chuck the disc (YEDS-18) beforehand, and disconnect the
power cord from the outlet.
2.
Connect oscilloscpe to test point TP (TE) on BD board.
3.
Connect test point (ADJ) on MAIN board to ground with lead
wire.
4.
The ADJ mode is set when the power cord is inserted into the
outlet and power is supplied.
5.
The fifth track is played automatically.
6.
Press the GROUP 3 button. (The tracking servo and the
sledding servo are turned OFF.)
7.
Check the level B of the oscilliscope's waveform and the A
(DC voltage) of the center of the Traverse waveform.
Confirm the following :
A/B x 100 = less than ± 22%
Traverse waveform
0V
8.
Press the GROUP 8 button. (The tracking servo and sledding
servo are turned ON.) Confirm the C (DC voltage) is almost
equal to the A (DC voltage) is step 7.
Traverse waveform
0V
Tracking servo
Sledding servo
OFF
9.
Disconnect the lead wire of TP1 (ADJ) connected in step 2.
Adjustment Location: BD board (See page 19)
VOLT/DIV : 200mV
TIME/DIV : 500ns
+0.25
level : 1.2
Vp-p
–0.20
Oscilloscope
Center of the waveform
B
A (DC voltage)
Level : 1.3
0.6 Vp-p
C (DC
voltage)
Tracking servo
Sledding servo
ON
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