6-2. ELECTRICAL ADJUSTMENT
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. S-Curve Check
oscilloscope BD board TP (FE1) TP (VC)
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 level : 1.2
+0.25 �0.20
Procedure : 1. Chuck the disc (YEDS-18) beforehand, and disconnect the power cord from the outlet. 2. Connect oscilloscope to test point TP (FE1) on BD board. 3. Connect test point TP1 (ADJ) on MAIN board to ground with lead wire. 4. The ADJ mode is set when the power cord is inserted into the outlet and power is supplied. 5. The fifth track is played automatically. 6. Press the CHECK button. 7. 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. Chuck the disc (YEDS-18) beforehand, and disconnect the power cord from the outlet. 2. Connect oscilloscpe to test point TP (TE) on BD board. 3. Connect test point TP1 (ADJ) on MAIN board to ground with lead wire. 4. The ADJ mode is set when the power cord is inserted into the outlet and power is supplied. 5. The fifth track is played automatically. 6. Press the GROUP 3 button. (The tracking servo and the sledding servo are turned OFF.) 7. 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%
A Within 3 ± 1 Vp-p B
Traverse waveform
Center of the waveform B
8. Pressing the 1/u button stops the output of the waveform (s curve). 9. After check, remove the lead wire connected in step 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. Adjustment Location: BD board
0V
A (DC voltage)
level : 1.3 ± 0.6 mVp-p
8. Press the GROUP 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 7.
Traverse waveform
Procedure : 1. Connect oscilloscope to test point TP (RF) on BD board. 2. Turn 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.
Tracking servo Sledding servo OFF
Tracking servo Sledding servo ON
9. Disconnect the lead wire of TP1 (ADJ) connected in step 2. Adjustment Location: MAIN board
