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CD SECTION
NOTE :
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
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. S Curve Check
oscilloscope BD board TP (FE) TP (VC) + �
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
Procedure : 1. Short-circuit SL502 of the video board to GND. 2. Connect oscilloscpe to test point TP (TE) on BD board. 3. Turned Power switch on. Press FUNCTION button to select CD. 4. Set a disc (YEDS-18) and play. 5. Press the PLAY MODE button. (The sledding servo is 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 ± 7%
Traverse waveform
A Within 3 ± 1 Vp-p B B Center of the 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
oscilloscope BD board TP (RF) TP (VC) + �
0V
A (DC voltage)
level : 500 mV ± 100 mVp-p
7. Press the PLAY MODE 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
0V
C (DC voltage)
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.
