Sony SLV-7700KME, Service Manual

Page: 100 / 135

7-6
2-6. VIDEO SYSTEM ADJUSTMENTS
For the video system adjustment, follow the adjustment procedures
given below as a rule. The color bar video signal supplied from the
pattern generator is used as the video input signal for the video
system adjustment of the recording mode. Check that the signal
satisfies the specified value designated in the “Check of input signal
(Fig. 7-2-2)”.
[Adjustment Sequence]
1)
X'tal OSC Check
2) SYNC AGC Check
3) White Clip/Dark Clip Check
4) REC Y Level Check
5) REC Chroma Level Check
6) Playback Level Check
2-6-1. X'tal OSC Check (MA-303 Board)
Mode Playback
Signal Alignment tape : Color bar portion
Measurement
IC304 pin
8
point
Measuring
Oscilloscope and Frequencycounter
instrument
Specified PAL : 4,433,619 ± 82 Hz
value NTSC : 3,579,545 ± 82 Hz
Note :
A frequency counter should be connected through a buffer
ampifier (oscilloscope, etc.) having a high impedance and a
low capacitance.
[Check Method]
1)
Check that the oscillation frequency satisfies the specified value
and that the oscillation voltage A is 300 ± 130 mVp-p (PAL)/
250 ± 110 mVp-p (NTSC).
Fig. 7-2-12.
2-6-2. SYNC AGC Check (MA-303 Board)
Mode E-E
Signal Color bar
Measurement LINE-1 OUT VIDEO terminal
point (terminated at 75
Ω
)
Measuring
Oscilloscope
instrument
Specified
A=1.0 ± 0.14 Vp-p
value
[Check Method]
1)
Check that the SYNC AGC level (A) satisfies the specified
value.
Fig. 7-2-13.
2-6-3. White Clip/Dark Clip Check (MA-303 Board)
Mode E-E
Signal Color bar
Measurement
IC302 pin
$•
point
Measuring
Oscilloscope
instrument
Specified White clip : A=190 ± 15%
value Dark clip : B=52 ± 10%
[Check Method]
1)
Check that the white clip level A is 190±15% to the white
(100%) level.
2) Check that the dark clip level B is 52±10% to the white (100%)
level.
Fig. 7-2-14.
A
White (100%)
A
H
White (100%)
100%
H
A
B