Sony HCD-GTX777 Service Manual page 29

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3. Mode: Playback
test tape
P-4-A100
(10 kHz, –10 dB)
L-CH
R-CH
in phase 45o
4. After the adjustments, apply suitable locking compound to
the parts adjusted.
Adjustment Location: Playback Head (Deck).
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oscilloscope
L
V H
R
waveform of oscilloscope
90 o 135o 180o
good wrong
forward
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HCD-GTX777/GTX787/GTX888
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CD SECTION
[TEST DISC LIST]
Use the following test disc on test mode.
• CD: YEDS-18 (PART No. 3-702-101-01)
PATD-012 (PART No. 4-225-203-01)
Note:
1. CD Block is basically designed to operate without adjustment.
Therefore, check each item in order given.
2. Use YEDS-18 (3-702-101-01) unless otherwise indicated.
3. Use an oscilloscope with more than 10MW impedance.
4. Clean the object lens by an applicator with neutral detergent
when the signal level is low than specifi ed value with the
following checks.
[S-CURVE CHECK]
BD93 board
TP106(FE)
TP124(VC)
Procedure :
1. Connect an oscilloscope to TP106 (FE) and TP124 (VC).
2. Turn the power on.
3. Load a disc (YEDS-18) and actuate the focus search. (In
Q Q
consequence of open and close the disc tray, actuate the focus
3 6 7 1 3 1 5
search)
4. Confi rm that the oscilloscope waveform (S-curve) is symmetrical
between A and B and confi rm peak to peak level within 3 ± 0.5
Vp-p.
S-curve waveform
Note: • Try to measure several times to make sure that 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.
co
.
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or
oscilloscope
+
–
0 5 8 2 9 9 4 2 8
symmetry
A
±
within 3 0.5Vp-p
B
m
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