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CD SECTION
Note :
1. CD Block basically constructed to operate without adjust-
ment. Therefore, check each item in order given.
2. Use YEDS-18
disc (3-702-101-01) unless otherwise indi-
cated.
3. Use the oscilloscope with more than 10M Q 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 Blas Adjustment
This adjustment is to be done when the optical block is replaced.
Adjustment procedure :
oscilloscope
(DC range)
BD board
__
TP (RF)
—<———_
T° +
TP (VC)
=
1. Connect oscilloscope to test point TP (VC) and TP (RF) on
BD board.
2. Turned power switch ON. (Stop mode)
. Put disc (YEDS-18) in and press the ta 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.
Ww
@ RF signal reference waveform (eye pattern)
VOLT/DIV : 0.2V
TIME/DIV : 500ns
1,3 + 0.3Vp-p
When observing the eye pattern, set the oscilloscope for AC
range and raise vertical sensitivity.
Adjustment Location : BD board (see page 16)
S-Curve Check
oscilloscope
BD board
en
Ss
TP (FEO)
a
Raa
Te +
TP (VC)
=
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 tumed 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
2.4 + 0.7Vp-p.
S-curve waveform
symmetry
within 2.4 + 0.7Vp-p
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:BorB: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 (see page 16)
RF Level Check
oscilloscope
BD board
PN
TP (RF)
—<——
TT" +
TP (VC)
<
Procedure :
1. Connect oscilloscope to test point TP (RF) on BD board.
2. Turmed Power switch on.
3. Put disc (YEDS-18) in and press the 10 button.
4. Confirm that oscilloscope waveform is clear and check RF
signal level is correct or not.
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
level: 1.3 + 0.3Vp-p
Adjustment Location : BD board (see page 16)
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