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5-10
No video picture, no sound.
Change CE3, D6 and R21.
No video picture,
no sound.
Check if the reset circuit consisting
of CE3, D6 and R21 is normal (at a
high level for tens of milliseconds,
then constantl
y
at 3.3V
)
.
Check whether there is
27MHz si
g
nal out
p
ut.
Check the loaded circuit
Crystal oscillator Y2 and
peripheral components
are defected or eroded.
No
No
No
Yes
Yes
Yes
27Mhz waveform
Trouble shooting chart
Check whether all the voltages
from the power board to the
decoder board are normal.
CVBS(R1 point) waveform
Check if there is 135MHz
signal output on R31.
Check whether
short-circuit or bad
solder on U1,U3
SDRAM(R31 PCLK) waveform
Check U2.
No
No
Reconnect the component in
Yes
Yes
Check if short-circuit and
bad solder exist on Pin 60
Yes
No