Fuser Temperature Control; Fuser Heater Protective Function - HP LaserJet Enterprise 700 M712 series Handbuch Zur Fehlerbehebung

Fuser temperature control

The fuser temperature control maintains the temperature of the fuser heater at its targeted temperature.
The DC controller monitors the FUSER TEMPERATURE signals (MFSRTH, S1FSRTH, S2FSRTH and
S3FSRTH) and sends the FUSER HEATER CONTROL signals (FSRD1 and FSRD2). The fuser heater
control circuit controls the fuser heater depending on the signals so that the fuser heater remains at the
targeted temperature.

Fuser heater protective function

The fuser heater protective function detects an abnormal temperature rise of the fuser and interrupts
power supply to the fuser heater. The following protective components prevent an abnormal
temperature rise of the fuser heater:
DC controller
●
The DC controller monitors the detected temperature of the thermistor. The DC controller releases
the relay (RL1001) to interrupt power supply to the fuser heater when it detects an abnormal
temperature.
Fuser heater safety circuit
●
The fuser heater safety circuit monitors the detected temperature of the thermistor. The fuser heater
safety circuit releases the relays (RL1001 and RL1002) or deactivates the fuser heater control
circuit to interrupt power supply to the fuser heater when it detects an abnormal temperature.
Thermoswitch
●
The contact of the thermoswitch is broken to interrupt power supply to the fuser heater when the
temperature of the fuser heater is abnormally high.
Current detection circuit
●
The current detection circuit monitors the current value flowing in the fuser heater control circuit,
and it releases the relay to interrupt power supply to the fuser heater when it detects an abnormal
current flow.
The DC controller deactivates the FUSER HEATER CONTROL signal and releases the relays
(RL1001 and RL1002) to interrupt power supply to the fuser heater when it detects out of a
specified current value of the CURRENT DETECTION signal (FSRCUR).
ENWW
Engine control system
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