Samsung ML-451 Series Service Manual page 214

4. Alignment and Troubleshooting
9) Remove the thermistor. Check if the thermistor has curled as shown below. If there is any contamination on
the film, clean it.
CAUTION
Be careful not to be scratched or curled the film.
10)Check if the thermistor connector on the main board is connected properly.
11) Check if the FDB connector is connected properly.
12)Check if the voltage in user environment is in this range (80V ~ 140V, 160V ~ 260V).
13)If there is no problems for above steps, update the firmware.
14)Replace the FDB. If the problem persists, replace the main board.
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