48
CD SECTION
Note:
1. CD Block is basically designed to operate without adjustment. There-
fore, check each item in order given.
2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use an oscilloscope with more than 10M
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. Level doesn’t change whichever with normal speed or with four times
speed.
6. Use the following jig.
• Extension jig (21 core) (Part No. J-2501-075-A)
CN101 on the BD (CD) board to CN1002 on the MD DIGITAL board
S Curve Check
Connection:
Procedure:
1. Connect an oscilloscope to test point TP (FE) and TP (VC) on
the BD (CD) board.
2. Turn the power on.
3. Put the 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)
4. Check the oscilloscope waveform (S-curve) is symmetrical
between A and B. And confirm peak to peak level within 3.6 ±
0.5 Vp-p.
S-curve waveform
Note:
• Try to measure several times to make sure than the ratio of A : B
or B : A is more than 10 : 7.
• Take sweep time as long as possible and light up the
brightness to obtain best waveform.
Checking Location: BD (CD) board
RF Level Check
Connection:
Procedure:
1. Connect an oscilloscope to test point TP (RF) and TP (VC) on
the BD (CD) board.
2. Turn the power on.
3. Put the disc (YEDS-18) in to playback the number five track.
4. Confirm that oscilloscope waveform is clear and check RF sig-
nal level is correct or not.
+
–
BD (CD) board
TP (FE)
TP (VC)
oscilloscope
(DC range)
A
B
symmetry
within 3.6
±
0.5 Vp-p
+
–
BD (CD) board
TP (RF)
TP (VC)
oscilloscope
(AC range)
Note:
A clear RF signal waveform means that the shape “
◊
” can be clearly
distinguished at the center of the waveform.
RF signal waveform
Checking Location: BD (CD) board
E-F Balance Check
Connection:
Procedure:
1. Connect an oscilloscpe to test point TP (TE) and TP (VC) on the
BD (CD) board.
2. Turn the power on.
3. Put the disc (YEDS-18) in to playback the number five track.
4. Press the
[REPEAT]
button. (The tracking servo and the sled-
ding servo are turned OFF)
5. Check the level B of the oscilliscope's waveform and the A (DC
voltage) of the center of the Traverse waveform.
Confirm the following :
A/B x 100 = less than ± 22%
Traverse Waveform
6. Press the
[REPEAT]
button. (The tracking servo and sledding
servo are turned ON)
Confirm the C (DC voltage) is almost equal to the A (DC volt-
age) is step 5.
Traverse Waveform
Checking Location: BD (CD) board
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
(normal speed)
level: 1.2
±
0.2 Vp-p
+
–
BD (CD) board
TP4 (TE)
TP (VC)
oscilloscope
(DC range)
0V
B
level: 1.3
±
0.6 Vp-p
Center of
the waveform
A (DC
voltage)
0V
Tracking servo
Sled servo
ON
C (DC
voltage)
Tracking servo
Sled servo
OFF
