4-9
No video picture, no sound.
Change
CE17, R47, D2,L30
No video picture,
no sound.
Check if the reset circuit
consisting of CE17, R47,
D2,L30 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 115MHz
signal output on L7.
Check the loaded circuit
Crystal oscillator Y1 and
peripheral components
are defected or eroded.
Check whether
short-circuit or bad
solder on U3, U6
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Reconnect the component in
short-circuit
Check U4.
27M waveform
SDRAM(L7 SDCLK) waveform
Check whether all the voltages
from the power board to the
decoder board are normal.
CVBS(R85 point) waveform
Trouble shooting chart
Go
No