Electrical Adjustmens - Sony D-EJ250 Service Manual

ELECTRICAL ADJUSTMENTS
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.
(J401)
VOLUME button : Minimum
HOLD switch : OFF
SECTION 4
Focus bias Check
Condition:
• Hold the set in horizontal state.
Connection:
oscilloscope
(AC range)
TP601(RF)
[MAIN BOARD] (SIDE B)
CN601
Q301 ECB
15
TP601
C304
(RF)
R603
C317
1
C302
C301
4
Procedure:
1. Connect the oscilloscope to the test point TP601(RF) 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 : 500ns
RF level
0.4 to 0.8 Vp-p
To watch the eye pattern, set the oscilloscope to AC range and
increase the vertical sensitivity of the oscilloscope for easy
watch-ing.
5. Stop revolving of the disc motor by pressing the x button.
7 7
D-EJ250