HCD-V8900, HCD-V8900AV, LBT-V8900AV - Sony Audio Service Manual (repair manual). Page 15

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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 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.

Note : A clear RF signal waveform means that the shape “

◊

” can

be clearly distinguished at the center of the waveform.

RF signal waveform

Procedure :
1. Connect oscilloscope to test point TP (FE) on BD board.
2. Connect between test point TP (FEI) and TP (VC) by lead wire.
3. Turned Power switch on.
4. Put 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.)

5. Check the oscilloscope waveform (S-curve) is symmetrical be-

tween A and B.
And confirm peak to peak level within 3±1 Vp-p.

S-curve waveform

oscilloscope

BD board

TP (FE)
TP (VC)

+
–

symmetry

A

B

Within 3 

±

 1 Vp-p

6. After check, remove the lead wire 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 bright-

ness to obtain best waveform.

oscilloscope

BD board

TP (RF)
TP (VC)

+
–

Procedure :
1. Connect oscilloscope to test point TP (RF) on BD board.
2. Turned Power switch on.
3. Put disc (YEDS-18) in to play the number five track.
4. Confirm that oscilloscope waveform is clear and check RF sig-

nal level is correct or not.

VOLT/DIV : 200mV
TIME/DIV : 500ns

level : 1.3           Vp-p

+0.25
–0.20

oscilloscope

BD board

TP (TE)
TP (VC)

+
–

Procedure :
1. Connect oscilloscpe to test point TP (TE) on BD board.
2. Connect the lead wire to both ends of the land of SL702 (ADJ)

and SL703 (AFADJ) of the VIDEO board.

3. Turned Power switch on. Press  FUNCTION  button to select

CD.

4. Short the lead wire.
5. Put disc (YEDS-18) in to play the number five track.
6. Press the  REPEAT  button. (The tracking servo and the sled-

ding servo are turned OFF.)

7. 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

0V

level : 1.3 

±

 0.6 Vp-p

A (DC voltage)

Center of the waveform

B

8. 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 voltage) is step 7.

Traverse waveform

0V

C (DC 
voltage)

Tracking servo
Sled servo
        OFF

Tracking servo
Sled servo
        ON

9. Remove the lead wire connected step 1.