Note :
A clear RF signal waveform means that the shape “
◊
” can
be clearly distinguished at the center of the waveform.
RF signal waveform
E-F Balance Check
Procedure :
1.
Connect test point TP1 (ADJ) to ground with a lead wire.
2.
Connect oscilloscope to test point TP (TE) on BD board.
3.
Turned Power switch on.
4.
Put disc (YEDS-18) in to play the number five track.
5.
Press the “3” button. (The tracking servo and the sledding servo
are turned OFF.)
6.
Check the level B of the oscilloscope's waveform and the A
(DC voltage) of the center of the Traverse waveform.
Confirm the following :
A/B
×
100 = less than ± 22%
Traverse waveform
7.
Press the “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 6.
Traverse waveform
8.
Disconnect the lead wire of test point TP1 (ADJ) connected in
step 1.
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 using an applicator with neutral detergent
when the signal level is low than specified value with the
following checks.
S Curve Check
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.
Turn Power switch on.
4.
Put disc (YEDS-18) in and turn Power switch on again and
actuate the focus search. (Actuate the focus search when disc
table is moving in and out.)
5.
Check if 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
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
Connect oscilloscope to test point TP (RF) on BD board.
Put disc (YEDS-18) in to play the number five track.
Confirm that oscilloscope waveform is clear and check if RF
signal level is correct or not.
SECTION 3
ELECTRICAL BLOCK CHECKING
BD board
TP (FE)
TP (VC)
oscilloscope
symmetry
A
B
within 3 ± 1 Vp-p
BD board
TP (TE)
TP (VC)
oscilloscope
0V
Center of the waveform
B
level : 1.3 ± 0.6 Vp-p
A (DC voltage)
0V
C (DC
voltage)
Tracking servo
Sledding servo
ON
Tracking servo
Sledding servo
OFF
VOLT/DIV : 200mV
TIME/DIV : 500ns
level :
1.25 ± 0.25 Vp-p
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