SECTION 5 ELECTRICAL ADJUSTMENTS
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 BSL board TP (FE) 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: 200 mV TIME/DIV: 500 ns
level: 1.2 +0.25 Vp-p �0.20
E-F Balance (1 Track Jump) Check
oscilloscope
Procedure: 1. Connect the test point TP (ADJ) on MAIN board to the ground with a lead wire on MAIN board. 2. Connect oscilloscope to test point TP (FE) on BSL board. 3. Turned Power switch on to set ADJ mode by TIMER SW OFF. 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. TIMER SW ON. 6. Press the �1� button (s-cuve observe mode). 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
BSL board TP (TE) TP (VC)
+ �
Procedure: 1. Connect oscilloscope to test point TP (TE) on BSL board. 2. Turned 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 oscilloscope�s waveform and the A (DC voltage) of the center of the Travers waveform. Confirm the following : A/B � 100 = less than ± 6 (%)
1 track jump waveform
A within 3 ± 1 Vp-p B
Center of the waveform B A (DC voltage)
Note: � Try to measure several times to make sure that 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
0V level : 1.5
+1.5 �0.5
Vp-p
symmetry
E-F Balance Check
oscilloscope
oscilloscope BSL board TP (RF) TP (VC)
+ �
BSL board TP (TE) TP (VC)
+ �
Procedure: 1. Connect oscilloscope to test point TP (RF) on BSL 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.
Procedure: 1. Connect the test point TP (ADJ) on MAIN board on the ground with a lead wire on MAIN board. 2. Connect oscilloscope to test point TP (TE) on BSL board. 3. Turn the Power switch on to set the ADJ mode. (TIMER SW OFF) 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.)
