— 11 —
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 the oscilloscope with more than 10M
Ω
impedance.
4. Clean an object lens by an applicator with neutral detergent
when the signal level is low than specified value with the
following checks.
5. When optical pickup is replaced during repair, perform the focus
bias adjustment.
Focus Bias Adjustment
This adjustment is to be done when the optical block is replaced.
Adjustment procedure:
1. Connect oscilloscope to test point TP (VC) and TP (RF) on BD
board.
2. Turned power switch ON. (Stop state)
3. Insert disc (YEDS-18) and press the
^
button.
4. Adjust RV101 so that the oscilloscope waveform is as shown in
the figure below (eye pattern).
A good eye pattern means that the diamond shape (
≈
) in the
center of the waveform can be clearly distinguished.
•
RF signal reference waveform (eye pattern)
When observing the eye pattern, set the oscilloscope for AC
range and raise vertical sensitivity.
S-Curve Check
Procedure:
1. Connect as oscilloscope to test point TP (VC) and TP (FEO) on
BD board.
2. Connect a lead wire between test point TP (FOK) and Ground.
3. Turned Power switch on.
4. Insert disc (YEDS-18) and turned Power switch on again to
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 that peak to peak level is within
2.4 ± 0.7 Vp-p.
S-curve waveform
+
–
BD board
TP (RF)
TP (VC)
oscilloscope
(DC range)
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level:
1.3
±
0.3Vp-p
+
–
BD board
TP (FEO)
TP (VC)
oscilloscope
A
B
symmetry
within 2.4
±
0.7 Vp-p
+
–
BD board
TP (RF)
TP (VC)
oscilloscope
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level:
1.3
±
0.3Vp-p
+
–
BD board
TP (TEO)
TP (VC)
oscilloscope
(DC range)
SECTION 4
ELECTRICAL ADJUSTMENTS
6. After check, remove the lead wire connected in step 2.
Note:
•
Try to measure several times to make sure that the ratio of
A:B or B:A is more than 10:7.
•
Select a longer sweep time and increase the brightness to
obtain best waveform.
RF Level Check
Procedure:
1. Connect oscilloscope to test point TP (VC) and TP (RF) on BD
board.
2. Turned Power switch on.
3. Insert the disc (YEDS-18) and press the
^
button.
4. Confirm that oscilloscope waveform is clear and check RF signal
level is correct.
Note: Clear RF signal waveform means that the shape “
≈
” can be
clearly distinguished at the center of the waveform.
RF signal waveform
E-F Balance (Traverse) Check
Procedure:
1. Set up the TEST mode step 3) AF-ADJUSTMENT. (see page
9.)
2. Connect as oscilloscope to test point TP (TEO) on BD board.
3. Turned Power switch on.
4. Insert the disc (YEDS-18) in and press the
^
button.
5. Confirm that the oscilloscope waveform is symmetrical on the
top and bottom in relation to 0V dc, and check the amplitude.
