— 8 —
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 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
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 if RF
signal level is correct or not.
BD board
TP (FE)
TP (VC)
oscilloscope
symmetry
A
B
within 3 ± 1 Vp-p
BD board
TP (RF)
TP (VC)
oscilloscope
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 TP (ADJ) to ground with a lead wire.
2. Connect oscilloscpe 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 oscilliscope'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 TP (ADJ) connected in step 1.
VOLT/DIV : 200mV
TIME/DIV : 500ns
level :
1.2
Vp-p
+0.25
–0.20
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
SECTION 3
ELECTRICAL BLOCK CHECKING
