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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
SECTION 4
ELECTRICAL ADJUSTMENTS
(J401)
– 8 –
Focus bias Check
Condition:
• Hold the set in horizontal state.
Connection:
oscilloscope
(AC range)
2 K Ω
TP635 (AGND)
[ MAIN BOARD] (Side B)
5
20
85
80
75
70
65
61
90
91
95
00
105
110
115
20
31
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
watch-ing.
5. Stop revolving of the disc motor by pressing the x button.
TP629 (RF)
60
55
50
45
40
35
RF level
0.4 to 0.5 Vp-p
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