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5
Check 11: Is the video circuit OK?
<Outline> Composite signal and component signal are output from DVD-LSI (IC1501), and are output from the
HOST I/F (CN1901) via a buffer circuit.
IC1501
Composite
DVD_LSI
Component Y
Component Cb
Component Cr
Video
DAC
section
Fig 11.1: Video circuit
<Checking method> Playback DVD-REF-A1 TITLE2 CHAPTER5 (WHITE 100%), and monitor COMPO signal with
an oscilloscope with GNDV1 (stylus) being the reference. Set the trigger mode to "TV trigger" and
the trigger line to "150 line".
Check point 1 (stylus)
NO.
1 COMPO
In case of NG, check the applicable line, the periphery of the major components in the drawing above, soldering of the
peripheral components and defective components.
COMPO signal
Pedestal level
Fig 11.2: Waveform for the case of composite white 100% output
<Video level readjustment method>
In case the video composite output is outside of the specification value, readjust the level according to the method
described below.
(Note : Units are exchanged, the video output is not adjusted. )
Turn the volume (VR1671) to adjust the video level within the range of 1.0 ± 0.02 Vpp.
The adjustment specification is 1.0 ± 0.02 Vpp.
IC1501
Y
LSI
Video
Cb
DAC
section
Cr
Fig 11.3: Video circuit (component)
5
6
AVCC5
Video buffer circuit
Specification value
Reference waveform
1 000 mVpp ± 5 %
Waveform 6
Reference
value
Color burst
Horizontal sync signal
AVCC5
Q1701
Video buffer circuit
Q1702
Video buffer circuit
Q1704
Video buffer circuit
AVH-P7900DVD/RE
6
7
CN1901
HOST I/F
COMPO
PEAK
Adjust this level within the
range of 1.0 ± 0.02 Vpp.
BOTTOM
CN1901
HOST I/F
Y
Cb
Cr
7
8
A
B
C
D
E
F
61
8
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