SONY HCDR770
Manual de Servicio

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 10 M� 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.

E-F Balance (1 Track Jump) Check
oscilloscope BD board TP (TE) TP (VC)
+ �

S-Curve Check
oscilloscope BD board TP (FE) TP (VC)
+ �

Procedure : 1. Connect oscilloscpe to TP (TE) and TP (VC). 2. Turn the power ON. 3. Load a disc (YEDS-18) and playback the number five track. 4. Press the ^ (CD) button. (Becomes the 1 track jump mode) 5. Confirm that the level B and A (DC voltage) on the oscilloscope waveform.
1 track jump waveform

Procedure: 1. Connect oscilloscope to TP (FE). 2. 3. 4. 5. Connect between TP (FE1) and TP (VC) by lead wire. Connect between TP (AGCCON) and TP (GND) by lead wire. Turn the power ON. Load a disc (YEDS-18) and actuate the focus search. (In consequence of open and close the disc tray, actuate the focus search) 6. Cofirm that the oscilloscope waveform (S-curve) is symmetrical between A and B. And confirm peak to peak level within 4 ± 1 Vp-p.
S-curve waveform
symmetry

center of waveform B 0V A (DC voltage)

level = 1.3 ± 0.6 Vp-p

symmetry

A Specified level: B � 100 = less than ± 22%

6. After check, remove the lead wire connected in step 1.
A within 4 ± 1 Vp-p B

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
oscilloscope 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. Turn the power ON. 4. Load a disc (YEDS-18) and playback. 5. Confirm that the oscilloscope waveform is clear and check RF signal level is correct or not. 6. After check, remove the lead wire connected in step 2.
Note: Clear RF signal waveform means that the shape ��� can be clearly distinguished at the center of the waveform.

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

level: 1.45 ± 0.3 Vp-p

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