Fuser Failure Detection - HP LASERJET ENTERPRISE M725dn Troubleshooting Manual

Fuser failure detection

The DC controller determines if the fuser functions properly. The DC controller determines a fuser
failure, interrupts the power supply to the fuser heater, and notifies the formatter of a failure state when
it encounters the following conditions:
Abnormally high temperature 1
●
The main thermistor detects 240°C (464°F) or higher for a specified period.
Abnormally high temperature 2
●
The sub thermistor 1 detects 230°C (446°F) or higher for a specified period during the WAIT
period.
The sub thermistor 1 detects 230°C (446°F) or higher for a specified period before INTR starts.
The sub thermistor 1 detects 300°C (572°F) or higher for a specified period.
Abnormally high temperature 3
●
Either one of the sub thermistor 2 or sub thermistor 3 detects 230°C (446°F) or higher for a
specified period during the WAIT period.
Either one of the sub thermistor 2 or sub thermistor 3 detects 230°C (446°F) or higher for a
specified period before INTR starts.
Either one of the sub thermistor 2 or sub thermistor 3 detects 300°C (572°F) or higher for a
specified period.
Abnormally low temperature 1
●
The main thermistor detects 60°C (140°F) or lower for a specified period during the WAIT period.
The main thermistor detects 70°C (158°F) or lower for a specified period during heater
temperature control of the INTR period.
The main thermistor detects the targeted temperature minus 40°C (104°F) or lower for a specified
period during heater temperature control or pressure roller cleaning of the PRINT period.
The main thermistor detects 80°C (176°F) or lower for a specified period during heater
temperature control or pressure roller cleaning of the PRINT period.
Abnormally low temperature 2
●
The sub thermistor 1 detects 60°C (140°F) or lower for a specified period during the WAIT
period.
Abnormally low temperature 3
●
Either one of the sub thermistor 2 or sub thermistor 3 detects 60°C (140°F) or lower for a specified
period during the WAIT period.
Abnormal temperature rise
●
The main thermistor detects the targeted temperature minus 10°C (50°F) or lower for a specified
period during heater temperature control of the INTR period.
ENWW
Engine control system
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