10
SECTION 5
ELECTRICAL BLOCK CHECKING
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 (With general remote commander)
Procedure :
1. Connect oscilloscope to test point TP (FE) on BD board.
2. Connect the test point JW003 (ADJ) on MAIN board to the
ground with a lead wire.
3. Turn ON the power.
4. Put disc (YEDS-18) in press
H
(play) button.
5. When the 11 button of the remote commander is pressed, the S
curve will be output continuously.
6. Check the oscilloscope waveform (S-curve) is symmetrical
between A and B. And confirm peak to peak level within 3
Vp-p.
S-curve waveform
7. 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.
oscilloscope
BD board
TP (FE)
TP (VC)
+ 1.5
– 1
symmetry
A
B
Within 3 Vp-p
+ 1.5
– 1
symmetry
A
B
Within 3.8
±
1.1 Vp-p
S Curve Check (Without general remote commander)
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. Connect both ends of TP R151 of the BD board to the lead wire.
4. Turn ON the power.
5. Put disc (YEDS-18) in and actuate the focus search. (actuate the
focus search when disc table is moving in and out.)
6. Check the oscilloscope waveform (S-curve) is symmetrical
between A and B. And confirm peak to peak level within 3.8
±
1
Vp-p.
7. After check, remove the lead wire connected in step 2 and 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.
RF Level Check
VOLT/DIV : 200mV
TIME/DIV : 500ns
level : 1.2
±
0.2 Vp-p
oscilloscope
BD board
TP (TE)
TP (VC)
S-curve waveform
oscilloscope
BD board
TP (RF)
TP (VC)
Procedure :
1. Connect oscilloscope to test point TP (RF) on BD board.
2. Turn ON the power.
3. Put disc (YEDS-18) in to play the number five track.
4. Confirm that oscilloscope waveform is clear and check RF sig-
nal level is correct or not.
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 (1 Track Jump) Check
(Without general remote commander)
Procedure :
1. Connect oscilloscpe to test point TP (TE) on BD board.
2. Turn ON the power.
3. Put disc (YEDS-18) in to play the number five track.
4. Press the
X
(Pause) button. (Becomes the 1 track jump mode)
5. 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%
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