Fujitsu DL7400 Maintenance Manual page 157

5.3.8 Surge Current Controller
2.8.1 Surge Current Controller
Surge current caused at power-on is controlled by the power thermistor (NTC thermistor) on the power supply board.
This section explains the surge current controller.
At power-on
The power thermistor is directly connected to the power supply input line and normally has several ohms of
resistance when power is turned on.
This resistance suppresses surge current at power-on.
During printer operation
Because the power thermistor heats by itself by input current during printer operation, resistance is lowered
down to about one-tenth of its initial value to reduce loss.
When power is turned on again
If the power is turned on again immediately after it is turned off, the power thermistor is still warm
and may have less suppression effects, and surge current exceeding the specified level may flow.
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