Cd Section - Sony HCD-MD555 Service Manual

CD SECTION

Note:
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 10MΩ 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.
S Curve Check
BD board
TP (FEO)
TP (VC)
Procedure :
1. Connect oscilloscope to test point TP (FEO) on SERVO board.
2. Connect between test point TP (FEI) and TP (VC) by lead wire.
3. Connect TP (AGCON) to ground by lead wire.
4. Turn U (power) switch on.
5. Put disc (YEDS-18) in and turn U (power) switch on again
and actuate the focus search. (actuate the focus search when
disc table is moving in and out.)
6. Check the symmetry of the oscilloscope waveform (S-curve)
and the level (p-p value).
7. After check, remove the lead wire TP (FOK) connected in step
2.
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.)
RF Level Check
BD board
TP (RF)
TP (VC)
Procedure :
1. Connect oscilloscope to test point TP (RF).
2. Turn U (power) switch on.
3. Put disc (YEDS-18) in to play.
4. Confirm that oscilloscope waveform is clear and check RF signal
level is correct or not.
oscilloscope
symmetry
A
level 2.4 ± 0.7Vp-p
B
oscilloscope
— 51 —
Note: A clear RF signal waveform means that the shape "◊" can
be clearly distinguished at the center of the waveform.
RF signal waveform
E-F Balance (Traverse) Check
BD board
TP (FEO)
TP (VC)
1. Solder the lead wire to TP308 (ADJ) on MAIN board.
2. Connect oscilloscope to test point TP (TE) on SERVO board.
3. Turn the U (power) switch on to set the ADJ mode.
4. Set the function switch to the CD position.
5. Connect the lead wire to ground, that is connected in step 1.
6. Insert the disc (YEDS-18) and start playing back.
7. Press the DISPLAY button. (Tracking servo and sled servo
are turned OFF.)
8. Check the level B of the oscilloscope's waveform and the A
(DC voltage) of the center of the Traverse waveform.
Confirm the following :
A/B × 100 = less than ± 22%
Traverse waveform
0V
9. Press the DISPLAY button. (The tracking servo and sledding
servo are turned ON.) Confirm the C (DC voltage) is almost
equal to the A (DC voltage) is step 8.
Traverse waveform
0V
Tracking servo
Sledding servo
OFF
10. Disconnect the lead wire of TP308 (ADJ) connected in step 1.
VOLT/DIV : 200mV
TIME/DIV : 500ns
level: 1.2 ± 0.2 Vp-p
oscilloscope
Center of the waveform
B
A (DC voltage)
level: 1.3 ± 0.6Vp-p
C (DC voltage)
Tracking servo
Sledding servo
ON