SONY HCDF250AV
Manual de Servicio

CD SECTION
Note :

1. 2. 3. 4.

CD Block is basically designed to operate without adjustment. Therefore, check each item in order given. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated. Use an oscilloscope with more than 10M� impedance. Clean the object lens by an applicator with neutral detergent when the signal level is low than specified value with the following checks.
oscilloscope BD board

10. Confirm that oscilloscope waveform is clear and check RF signal level is correct or not. 11. Turn OFF the power, and remove the lead wire connected at step 7. Note : A clear RF signal waveform means that the shape ��� can be clearly distinguished at the center of the waveform.
RF signal waveform VOLT/DIV : 200mV TIME/DIV : 500ns level : 1.8 ± +0.3 Vp-p �0.2

TP (FE) TP (VC)

S Curve Check Procedure : 1. Press the 1/u button to turn ON the power . 2. 3. 4. 5. 6. 7. Open the front cover, and press the CD PLUS ONE button. Set the disc (YEDS-18) into the �PLUS ONE� slit. Close the front cover, and chuck the disc. Press the 1/u button to turn OFF the power. Connect the oscilloscope to TP (FE) of the BD board. Connect TP (ADJ) of the MAIN board and connect TP (GND) with a lead wire. 8. Press the 1/u button to turn ON the power. 9. The first track will be played back automatically. When the CHECK button is pressed, �S JI� will be displayed on the fluorescent indicator tube, and focus search will be repeated. 10. Check the oscilloscope waveform (S-curve) is symmetrical between A and B. And confirm peak to peak level within 1.8 ± 0.6 Vp-p.
S-curve waveform symmetry

E-F Balance (Traverse) Check The procedure for this checking method differs for when a general remote control unit is used and not used.
oscilloscope BD board TP (TE) TP (VC)

When a general remote commander is used: 1. Press the 1/u button to turn ON the power. 2. Open the front cover, and press the CD PLUS ONE button. 3. Set the disc (YEDS-18) into the �PLUS ONE� slit. 4. Close the front cover, and chuck the disc. 5. Press the 1/u button to turn OFF the power. 6. Connect the oscilloscope to TP (TE) of the BD board. 7. Connect TP (ADJ) of the MAIN board and connect TP (GND) with a lead wire. 8. Press the 1/u button to turn ON the power. 9. Playback the fifth track of the disc. 10. Press the 3 button on the remote commander. (The tracking servo and the sledding servo are turned OFF.) 11. 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 ± 10%
Traverse waveform Center of the waveform

A within 1.8 ± 0.6Vp-p B

11. Turn OFF the power, and remove the lead wire connected at step 7. 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.
0V

B A (DC voltage)

RF Level Check
oscilloscope BD board TP (RF) TP (VC) level : 0.7 ± 0.3 Vp-p 12. Press the 8 button on the remote control unit. (The tracking servo and sledding servo are turned ON.) Confirm the C (DC voltage) is almost equal to the A (DC voltage) is step 11. Traverse waveform

Procedure : 1. Press the 1/u button to turn ON the power. 2. Open the front cover, and press the CD PLUS ONE button. 3. Set the disc (YEDS-18) into the �PLUS ONE� slit. 4. Close the front cover, and chuck the disc. 5. Press the 1/u button to turn OFF the power. 6. Connect the oscilloscope to TP (RF) of the BD board. 7. Connect TP (ADJ) of the MAIN board and connect TP (GND) with a lead wire. 8. Press the 1/u button to turn ON the power. 9. Playback the fifth track of the disc.

C (DC 0V Tracking servo Sled servo ON voltage)

Tracking servo Sled servo OFF

13. Turn OFF the power, and remove the lead wire connected at step 7.

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