19
SECTION 7
ELECTRICAL ADJUSTMENT
1. CD Block is basically designed 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 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 fol-
lowing checks.
S-CURVE CHECK
Procedure :
1. Chuck the disc (YEDS-18) beforehand, and remove the power
cord from the outlet.
2. Connect oscilloscope to test point TP (FE1) on BD board.
3. Connect TP4 (ADJ) on MAIN board to ground with lead wire.
4. The ADJ mode is set when the power cord is inserted into the
outlet and power is supplied.
5. The fifth track is played automatically.
6. Press the
[CHECK]
button.
7. Check the oscilloscope waveform (S-curve) is symmetrical
between A and B. And confirm peak to peak level within
3±1 Vp-p.
S-curve waveform
8. Pressing the
I
/
1
button stops the output of the waveform
(s-curve).
9. After check, disconnect the lead wire connected in step 3.
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.
Adjustment Location: BD board
RF LEVEL CHECK
Procedure :
1. Connect oscilloscope to test point TP (RFO) on BD board.
2. Turn Power ON.
3. Put disc (YEDS-18) in to play the number five track.
4. Confirm that oscilloscope waveform is clear and check RF
signal level is correct or not.
oscilloscope
(DC range)
BD board
TP (FE1)
TP (VC)
symmetry
A
B
Within 3
±
1 Vp-p
oscilloscope
(AC range)
BD board
TP (RFO)
TP (VC)
Note:
A clear RF signal waveform means that the shape “
” can be clearly
distinguished at the center of the waveform.
RF signal waveform
Adjustment Location: BD board
E-F BALANCE CHECK
Procedure :
1. Chuck the disc (YEDS-18) beforehand, and disconnect the
power cord from the outlet.
2. Connect oscilloscpe to test point TP (TE) on BD board.
3. Connect TP4 (ADJ) on MAIN board to ground with lead wire.
4. The ADJ mode is set when the power cord is inserted into the
outlet and power is supplied.
5. The fifth track is played automatically.
6. Press the
[GROUP 3]
button. (The tracking servo and the sled-
ding servo are turned OFF.)
7. Check the level B of the oscilliscopes 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
8. Press the
[GROUP 8]
button. (The tracking servo and sled-
ding servo are turned ON.) Confirm the C (DC voltage) is al-
most equal to the A (DC voltage) is step 7.
Traverse waveform
9. Disconnect the lead wire connected in step 3.
Adjustment Location: MAIN board
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level: 1.2 Vp-p
+0.25
–0.20
oscilloscope
(DC range)
BD board
TP (TE)
TP (VC)
0V
level : 1.3
±
0.6 mVp-p
A (DC voltage)
Center of the waveform
B
0V
C (DC
voltage)
Tracking servo
Sledding servo
OFF
Tracking servo
Sledding servo
ON
s
