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No video picture, no sound.
No video picture,
Check
voltages from the power
board to the decoder board
are normal.
Check if the reset circuit consisting
of Q1,Q2,CE6 is normal
(at a high level for tens of milliseconds,
then constantly at 0V).
Check whether there is
27MHz signal output.
Check if there is 133MHz
signal output on R56.
5-8
no sound.
Go
whether
all
the
Yes
Yes
Yes
SDRAM(R49 SDCLK) waveform
Yes
Check U1.
No
Check the loaded circuit
CVBS(L30 point) waveform
No
Change Q1,Q2
Crystal oscillator Y1 and
No
peripheral components
are defected or eroded.
Check whether
No
short-circuit or bad
solder on U1, U5
Yes
Reconnect the component in
short-circuit
Trouble shooting chart
27M waveform
No
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