22
HCD-GPX9
CD SECTION
Note:
1. CD Block is basically constructed to operate without
adjustment.
2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use an oscilloscope with more than 10 M
Ω
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.
5. Check the focus bias check when optical block is replaced.
FOCUS BIAS CHECK
Procedure :
1. Connect the oscilloscope to TP012 (RFACO) and TP013 (VC)
on the BD board.
2. Insert the disc (YEDS-18). (Part No. : 3-702-101-01)
3. Press the
[ CD]
button.
4. Confirm 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)
+
–
BD board
TP012 (RFACO)
TP013 (VC)
oscilloscope
(DC range)
VOLT/DIV: 0.2 V (with the 10: 1 probe in use.)
TIME/DIV: 500 ns
0.7
When observing the eye pattern, set the oscilloscope
for AC range and raise vertical sensitivity.
0.3 Vp-p
TP013
(VC)
u
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