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� 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) BD board
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 : 1.3 �0.20 Vp-p
+0.25
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 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
TP (TE) TP (VC)
Procedure : 1. Connect oscilloscpe to test point TP (TE) on BD board. 2. Turn Power switch on. 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%
1 track jump waveform
A within 3 ± 1 Vp-p B B A (DC voltage) 0V 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)
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.
Procedure : 1. Connect oscilloscpe to test point TP (TE) on BD board. 2. Connect the test point TP1 (ADJ) on MAIN board to the ground with a lead wire. 3. Turn the Power switch on to set the ADJ mode. 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.)
