SONY DE770
Manual de Servicio

SECTION 4 ELECTRICAL ADJUSTMENTS
The CD section adjustments are done automatically in this set. In case of operation check, confirm that focus bias. Precautions for Check 1. Perform check in the order given. 2. Use YEDS-18 disc (Part No.: 3-702-101-01) unless otherwise indicated. 3. Power supply voltage requirement: DC4.5 V in DC IN jack. VOLUME button : Minimum AVLS switch HOLD switch : NORM : OFF Focus bias Check Condition: � Hold the set in horizontal state. Connection:
oscilloscope (AC range)
MAIN board TP629 (RF) TP635 (AGND) 2 k�

+ �

Checking Location: � MAIN board (Side A) �

Procedure: 1. Connect the oscilloscope to the test points TP629 (RF) and TP635(AGND) on the MAIN board. 2. Set a disc. (YEDS-18) 3. Press the u button. 4. Check the oscilloscope waveform is as shown below. A good eye pattern means that the diamond shape (�) in the center of the waveform can be clearly distinguished.

RF Signal reference Waveform (Eye Pattern)
VOLT/DIV : 100 mV (With the 10:1 probe in use) TIME/DIV : 500 ns

TP 629 (RF) TP 635 (AGND) RF level 0.35 to 0.65 Vp-p

To watch the eye pattern, set the oscilloscope to AC range and increase the vertical sensitivity of the oscilloscope for easy watching.

5. Stop revolving of the disc motor by pressing the x button.

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