Electrical Adjustments - Sony Walkman D-E777 Service Manual

D-E777/EJ721/EJ725
The CD section adjustments are done automatically in this set.
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 : NORM
HOLD switch : OFF
8
SECTION 4

ELECTRICAL ADJUSTMENTS

(J401)
Focus bias Check
Condition:
• Hold the set in horizontal state.
Connection:
oscilloscope
(AC range)
2 K Ω
TP635 (GND)
[ MAIN BOARD] (Side B)
EXCEPT
US MODEL
3
4 5
EXCEPT
US MODEL
20 16
15 11
5 6 10
EXCEPT
US JEW
Procedure:
1. Connect the oscilloscope to the test points TP629 (RF) and TP635
(GND) 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 cen-
ter 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 : 500ns
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.
TP629 (RF)
1
3
8
9
RF level
0.45 to 0.65 Vp-p (D-E777/EJ725)
0.38 to 0.6 Vp-p (D-EJ721)
US M
1
16