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SECTION 4 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� 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.
Note:
A clear RF signal waveform means that the shape ��� can be clearly distinguished at the center of the waveform.
RF signal waveform
VOLT/DIV : 200mV TIME/DIV : 500ns
S Curve Check
oscilloscope BD board TP (FE1) TP (VC)
level : 1.2 ± 0.2 Vp-p
E-F Balance (1 Track Jump) Check (without general remote commander)
oscilloscope BD board TP (TE) TP (VC)
Procedure : 1. Connect oscilloscope to test point TP (FE1) on BD board. 2. Connect between test point TP (FE2) 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 4.5 ± 1 Vp-p.
S-curve waveform
symmetry
A Within 4.5 ± 1 Vp-p B
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 P (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%
Center of the waveform
B
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.
0V
+ 0.7 � 0.6 Vp-p
A (DC voltage)
level : 1.3
symmetry
1 track jump waveform
RF Level Check
oscilloscope BD board TP (RF) TP (VC) TP (TE) TP (VC) BD board
oscilloscope
E-F Balance Check (With general remote commander) 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 signal level is correct or not. Procedure : 1. Turn ON the power, put disc (YEDS-18), turn OFF the power. 2. Connect the test point TP2 (ADJ) on MAIN board to the ground with a lead wire. 3. Connect oscilloscope to test point TP (TE) on BD board. 4. Turn the Power switch on to set the ADJ mode, automaticaly play the number five track. 5. Press the 3 button. (The tracking servo and the sledding servo are turned OFF.)
� 17 �
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