– 9 –
CD SECTION
Note :
1. CD Block 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.
Focus Bias Adjustment
This adjustment is to be done when the optical block is replaced.
Adjustment procedure :
+
–
oscilloscope
(DC range)
TP (RF)
TP (VC)
BD borad
+
–
TP (FEO)
TP (VC)
BD borad
1. Connect oscilloscope to test point TP (VC) and TP (RF) on main
board.
2. Turned power switch ON. (Stop mode)
3. Put disc (YEDS-18) in 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.
oscilloscope
5. Check the oscilloscope waveform (S-curve) is symmetrical be-
tween A and B. And confirm peak to peak level within
2.4
±
0.7Vp-p.
r
RF signal reference waveform (eye pattern)
When observing the eye pattern, set the oscilloscope for AC range
and raise vertical sensitivity.
S-Curve Check
VOLT / DIV : 0.2V
TIME / DIV : 500ns
1.3
±
0.3Vp-p
S-curve waveform
within 2.4
±
0.7Vp-p
symmetry
A
B
6. After check, remove the lead wire connected in step 2.
Note :
r
Try to measure several times to make sure that the ratio of
A : B or B : A is more than 10 : 7.
r
Take sweep time as long as possible and light up the
brightness to obtain best waveform.
RF Level Check
oscilloscope
Note :
Clear RF signal waveform means that the shape “
◊
” can be clearly
distinguished at the center of the waveform.
level : 1.3
±
0.3Vp-p
VOLT / DIV : 200mV
TIME / DIV : 500ns
RF signal waveform
oscilloscope
(DC range)
E-F Balance Check
Procedure :
1. Ground CD main board IC301 pin
#ª
(JW201) with the lead
wire.
2. Connect oscilloscope to test point TP (TEO) on BD board.
3. Turned Power switch on.
4. Put disc (YEDS-18) in and press the
button.
5. Confirm that the osilloscope waveform is symmetrical on the
top and bottom in relation to 0V, and check this level.
Procedure :
1. Connect oscilloscope to test point TP (FEO) and BD board.
2. Connect between test point TP (FOK) and GND by lead wire.
3. Turned Power switch on.
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.)
+
–
BD borad
TP (TEO)
TP (VC)
+
–
TP (RF)
TP (VC)
BD borad
Procedure :
1. Connect oscilloscope to test point TP (RF) on BD board.
2. Turned Power switch on.
3. Put disc (YEDS-18) in and press the
button.
4. Confirm that oscilloscope waveform is clear and check RF signal
level is correct or not.
