HP Enterprise 500 manual Fuser failure detection

Fuser failure detection

When the DC controller detects any of the following conditions, it determines that the fuser has failed. The DC controller then interrupts power to the fuser heaters and notifies the formatter.

●Abnormally high temperatures: Temperatures are too high for any of the following components, at any time:

◦TH1: 230° C (446° F) or higher

◦TH2: 285° C (545° F) or higher

◦TH3: 285° C (545° F) or higher

●Abnormally low temperatures: Temperatures are too low at any of the following components after the product has initialized.

◦TH1: 120° C (248° F) or lower

◦TP2 or TP3: 100° C (212° F) or lower

Or, the temperature drops in either of the thermopiles (TP1 and TP2) by 30° C (86° F) or more within a specified length of time.

●Abnormal temperature rise: The DC controller determines an abnormal temperature rise if the detected temperature of TH1 does not rise 2° C within a specified time period after the fuser motor is turned on, or if the detected temperature of the thermistors does not rise to a specified temperature for a specified time after the fuser motor is turned on.

●Thermistor open: The DC controller determines a thermistor open if:

◦The detected temperature of TH1 is kept at 12° C (53° F) or lower for a specified time after the fuser motor is turned on.

◦The detected temperature of TH2 is kept at 4° C (39° F) or lower for a specified time.

◦The detected temperature of TH3 is kept at 4° C (39° F) or lower for a specified time.

●Drive-circuit failure: The DC controller determines a drive-circuit failure:

◦If the detected power supply frequency is out of a specified range when the printer is turned on or during the standby period

◦If the current detection circuit detects an out of specified current value

●Fuser discrepancy: The DC controller determines a fuser type mismatch when it detects an unexpected fuser unit presence signal. The product has two fusers for 110 V or 220 V input power.

18 Chapter 1 Theory of operation ENWW