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SECTION 5
ELECTRICAL ADJUSTMENTS
Procedure :
1.
Connect oscilloscpe to test point TP (TE) on BD board.
2.
Turned Power switch on.
3.
Connect the SL502 on the VIDEO board with solder.
4.
Put disc (YEDS-18) in to play the number two track.
5.
Press the DNR button. (The tracking servo and the sledding
servo are turned OFF.)
6.
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
Note : A clear RF signal waveform means that the shape “
◊
” can
be clearly distinguished at the center of the waveform.
RF signal waveform
CD SECTION
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
Ω
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 (FE)
TP (VC)
BD board
TP (RF)
TP (VC)
level : 1.3 p-p
TP (TE)
TP (VC)
BD board
C (DC
voltage)
Tracking servo
Sled servo
ON
Tracking servo
Sled servo
OFF
Procedure :
1.
Connect oscilloscope to test point TP (FE) on BD board.
2.
Connect between test point TP (FEI) and TP (VC) by lead wire.
3.
Turned Power switch on.
4.
Put disc (YEDS-18) in and turned Power switch on again and
actuate the focus search. (actuate the focus search when disc
table is moving in and out.)
5.
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
symmetry
within 3
±
1 Vp-p
A
B
6.
After check, remove the lead wire connected in step 2.
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.
RF Level Check
Procedure :
1.
Connect oscilloscope to test point TP (RF) on BD board.
2.
Turned 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.
E-F Balance (Traverse) Check
oscilloscope
oscilloscope
+0.25
–0.20
oscilloscope
7.
Press the DNR 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 6.
Traverse waveform
Center of the waveform
B
A (DC voltage)
level : 1.3
±
0.6 Vp-p
VOLT/DIV : 200mV
TIME/DIV : 500ns
8.
Remove the soldering installed in step 3.
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