Sony HCD-VZ50MD Service Manual page 36

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 fol-
lowing checks.
S-Curve Check
BD board
TP(FEO)
TP(VC)
Procedure :
1. Connect oscilloscope to TP (FEO).
2. Connect between TP (FEI) and TP (VC) by lead wire.
3. Connect between TP (AGCCON) and TP (GND) by lead wire.
4. Turn ?/1 button on.
5. Load a disc (YEDS-18) and actuate the focus search. (In conse-
quence of open and close the disc tray, actuate the focus search)
6. Confirm that the oscilloscope waveform (S-curve) is symmetri-
cal between A and B. And confirm peak to peak level within 4
±1 Vp-p.
S-curve waveform
7. After check, remove the lead wire connected in step 2 and 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.
RF Level Check
BD board
TP(RF)
TP(VC)
Procedure :
1. Connect oscilloscope to TP (RF).
2. Connect between TP (AGCCON) and TP (GND) by lead wire.
3. Turned ?/1 button on.
4. Load a disc (YEDS-18) and playback.
5. Confirm that oscilloscope waveform is clear and check RF sig-
nal level is correct or not.
6. After check, remove the lead wire connected in step 2.
36
Oscilloscope
Symmetry
A
Wthin 4 ±1Vp-p
B
Oscilloscope
Note : Clear RF signal waveform means that the shape " ◊ " can be
clearly distinguished at the center of the waveform.
RF signal waveform
E-F Balance (1 Track jump) Check
BD board
TP(TEO)
TP(VC)
Procedure :
1. Connect oscilloscope to TP (TEO) and TP (VC).
2. Turned ?/1 button on.
3. Load a disc (YEDS-18) and playback the number five track.
4. Press the u button. (Becomes the 1 track jump mode.)
5. Confirm that the level B and A (DC voltage) on the oscillo-
scope waveform.
1 track jump waveform
0 V
Level=1.3 ±0.6 Vp-p Symmetry
A × 100 = less than ± 22 %
Specified level:
B
6. After check, remove the lead wire connected in step 1.
Adjustment Location:
[BD (CD) BOARD] (Conductor Side)
TP (RF)
TP (VC)
TP (AGCCON)
TP (TEO)
TP (FE0)
TP
IC103
(GND)
VOLT/DIV : 200mV
TIME/DIV : 500ns
Level : 1.45 ± 0.3Vp-p
Oscilloscope
Center of
waveform
B
A (DC voltage)
IC101