Cd Section; S-Curve Check; Rf Level Check; E-F Balance (Traverse) Check - Sony HCD-V4800 Service Manual

CD SECTION

Notes:
1. CD block basically constructed to operate without adjustment. There-
fore, check each item in order given.
2. Use YEDS-18 disc (Part No.: 3-702-101-01) unless otherwise indicated.
3. Use the oscilloscope with more than 10 MΩ impedance.
4. Clean an object lens by an applicator with neutral detergent when the
signal level is low than specified value with the following checks.

S-Curve Check

Connection:
BD board
TP (FE)
TP (VC)
Procedure:
1. Connect the oscilloscope to TP (FE) and TP (VC) on BD board.
2. Connect the TP (FEI) and TP (VC) with lead wire.
3. Turned power switch on.
4. Put disc (YEDS-18) in and turned power switch on again and
actuate the focus search.
5. Confirm that the oscilloscope waveform (S-curve) is symmetri-
cal between A and B. And confirm peak to peak level within
3.0 ± 1.0 Vp-p.
S-curve waveform
6. After check, remove the lead wire connected in step 2.
Note: • Try to measure several times to make sure that 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

Connection:
BD board
TP (RF)
TP (VC)
Procedure:
1. Connect the oscilloscope to TP (RF) and TP (VC) on BD board.
2. Turned power switch on. (stop mode)
3. Put disc (YEDS-18) in and press the · button.
4. Confirm that the oscilloscope waveform is clear and check RF
signal level is correct or not.
Note: Clear RF signal waveform means that the shape "≈" can be clearly
distinguished at the center of the waveform.
oscilloscope
+
–
symmetry
A
within 3.0 ± 1.0 Vp-p
B
oscilloscope
(AC range)
+
–
RF signal waveform
When observing the eye pattern, set the oscilloscope for AC range
and raise vertical sensitivity.

E-F Balance (Traverse) Check

Connection:
BD board
TP (TE)
TP (VC)
Procedure:
1. Connect the oscilloscope to TP (TE) and TP (VC) on BD board.
2. Turned power switch on.
3. Connect the SL702 and SL703 on the VIDEO board with sol-
der.
4. Put disc (YEDS-18) in and press the · button, and play the
number five track.
5. Press the REPEAT button. (The tracking servo and the sled-
ding servo are turned off.)
6. Confirm that 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
0 V
7. Press the REPEAT button. (The tracking servo and the sled-
ding servo are turned on.) Confirm that the C (DC voltage) is
almost equal to the A (DC voltage) is step 6.
Traverse waveform
0 V
Tracking servo
8. After check, remove the soldering installed in step 3.
– 21 –
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
(with the 10: 1 probe
in use)
+0.25
level: 1.3
–0.20
oscilloscope
(DC range)
+
–
Center of the waveform
B
A (DC voltage)
level: 1.3 ± 0.6 Vp-p
Tracking servo
Sled servo Sled servo
OFF ON
Vp-p
C (DC
voltage)