CD SECTION
Note: 1. CD Block is basically constructed 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
Note: 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
Adjustment Location: BD board Procedure : 1. Connect the oscilloscope to test points TP (FE) and TP (VC). 2. Connect TP (FEI) and GND, and TP (AGCCON) and GND of the BD board with lead wires. 3. Press the 1/u button to turn the set ON. 4. With the disc (YEDS-18) loaded, press the ^ button and perform focus search. (Focus search will be performed in the same way even while the disc table is pushed in and out.) 5. Check the symmetry and peak to peak level of the oscilloscope waveform (S curve) at this time.
S-curve waveform
symmetry
Adjustment Location: BD board Procedure : 1. Connect oscilloscpe to test point TP (TE) on BD board. 2. Short-circuit SL502 of the video board to GND. 3. Turned Power switch on. Press FUNCTION button to select CD. 4. Put disc (YEDS-18) in to play the number five track. 5. Press the PLAY MODE/DOLBY NR button. (The tracking servo and the sledding servo are 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 ± 22%
Traverse waveform A Within 4.0 ± 1.0 Vp-p B 0V B A (DC voltage) 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. Adjustment Location: BD board RF Level Check
oscilloscope BD board TP (RF) TP (VC) + �
level : 1.3 ± 0.6 Vp-p
7.
Press the PLAY MODE/DOLBY NR 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
0V
C (DC voltage)
Procedure : 1. Connect oscilloscope to test point TP (RF) and TP (VC) on BD board. 2. Connect TP (AGCCON) and GND of the BD board with lead 3. 4. 5. 6. wires. Press the 1/u button to turn the set ON. Put disc (YEDS-18) in and playback 5track. Confirm that oscilloscope waveform is clear and check RF signal level is correct or not. After check, remove the lead wire connected in step 2.
Tracking servo Sled servo OFF
Tracking servo Sled servo ON
8.
Desolder the short-land (SL502) short-circuited at step 2.
