Prima PH50D8, Service Manual

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2
6 -
4) VGA No Picture
yes no
normal abnormal yes no
normal abnormal
6) DVI no picture
If VGA works normally, it’s enough only to check the connection between socket X401and N403
and the operation status of N403. R414 is the matching resistance for its input. If it has problem the
DVI image would become abnormal.
5
．
Abnormal picture :
Peculiar color, which may be caused by the following phenomena:
A certain differential wire pair of LVDS
（
RX0+/-
，
RX1+/-
，
RX2+/-
，
RX3+/-
）
is abnormal,
which may lead to lack of color ( it’s not a complete loss of color);
Failure with resistor rows R550~R555
，
which may lead to loss of corresponding color from
the gray degree corresponding to the picture of all channels. Through self signal check by
PW181, the failure is still there.
Failure with resistor rows R419, R421, R425, R427, R431, R432
，
which may lead to loss of
corresponding color from the gray degree corresponding to the picture of channels
VGA/YPRPB/DVI.
Failure with resistor rows R415, R418, R422, R424, R429, R430
，
which may lead to loss of
corresponding color from the gray degree corresponding to the picture of channel DVI.
Failure with resistor rows R342, R343, R344, R345
，
which may lead to loss of
corresponding color from the gray degree corresponding to the picture of sub-channels
TV/AV/YCRCB, or lead to abnormal brightness.
If input YPRPB signal is normall
If the mode of VGA (lower right corner
of screen OSD) identifiable
Measure the input line/field synch.
signal of 81 and 82 of N403
Check N402
and its
peripheral
Check N403 and its
peripheral,especially its output
signals (CLK, line/field synch.
and enable etc.)
Check N403 and
its peripheral
Input interface
circuit has
problem
If the two TV pictures
are normal
Check input
circuit of GPORT
of N501