TOSHIBA SD-280EKB
Manual de Servicio

1-10
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Trouble shooting chart

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Check whether all the voltages from the power board to the decoder board are normal.

No Check the loaded circuit
CVBS(R1 point) waveform

Yes

Check if the reset circuit consisting of CE3, D6 and R21 is normal (at a high level for tens of milliseconds, then constantly at 3.3V).

No Change CE3, D6 and R21.

27Mhz waveform

Yes Crystal oscillator Y2 and
Check whether there is 27MHz signal output.

No

peripheral components are defected or eroded.

Yes

Check if there is 135MHz signal output on R31.

No

Check whether short-circuit or bad solder on U1,U3

SDRAM(R31 PCLK) waveform

No

Yes

Check if short-circuit and bad solder exist on Pin 60

Check U2. No

Yes Yes Reconnect the component in