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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 Bias Adjustment
This adjustment is to be done when the optical block is replaced.
Adjustment procedure :
oscilloscope
(DC range)
BD board
err
1. Connect oscilloscope to test point TP (VC) and TP (RF) on
main board.
. Ground display board IC704 pin @ with the lead wire.
. Turned power switch ON. (Stop mode)
. Put disc (YEDS-18) in and press the >I] button.
. Press the Pll button again. (Tracking servo ON)
. 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.
7. Remove the lead wire connected in step2.
NNW
WD
@ RF signal reference waveform (eye pattern)
XK EXTOL
\ RRR
\
0000008
WAXRHIAN
ny
When observing the eye pattern, set the oscilloscope for AC.
range and raise vertical sensitivity.
VOLT/DIV : 0.2V
TIME/DIV : 500ns
1.3 + 0.3Vp-p
S-Curve Check
oscilloscope
BD board
my,
TP (FEO)
o—'———y-0 +
TP (VC)
-
Procedure :
1. Connect oscilloscope to test point TP (FEO) and BD board.
2. Connect between test point TP (FOK) and TP (VC) by lead
wire.
3. Tumed Power switch on.
4. Put disc (YEDS-18) in and tured 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
3.8 + 1.1Vp-p.
S-curve waveform
symmetry
within 3.8 + 1.1Vp-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.
RF Level Check
oscilloscope
BD board
—_"_o
TP (RF)
eto
+
TP (VC)
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 PI] 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 " ©
clearly distinguished at the center of the waveform.
"
can be
RF signal waveform
AKA?
\ WHR
AAA
AAA
VOLT/ DIV: 200mV
TIME / DIV ; 500nS
WA
A)
V
level: 1.3 + 0.3Vp-p
E-F Balance Check
oscilloscope
(DC range)
BD board
_—
TP(TEQ) o=t————7-0 +
TP (VC)
Procedure :
1. Ground display board IC701 pin @ with the lead wire.
Connect oscilloscope to test point TP (TEO) on BD board.
Turned Power switch on.
Put disc (YEDS-18) in and press the >] button.
Confirm that the oscilloscope waveform is symmetrical on
the top and bottom in relation to OV, and check this level.
Ne
ae
—
9
—
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