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10-360 Heat Roll Overheat Thermistor Failure RAP
The Heat Roll Overheat Thermistor detected an abnormal resistance value continuously for
more than 1500 msec (Heat Roll Overheat Thermistor disconnected).
Initial Actions
Refer to BSD 10.2 and 10.12 for the following procedure.
• Open the Drawer and extend it to the service position. Perform the following:
– Remove the Oil Cartridge (PL 8.1).
– Remove the Front Cover (PL 8.1).
– Remove the Top Cover (PL 8.2).
• Check the Heat Roll Overheat Thermistor for cleanliness, damage and excessive wear at
the point where the Thermistor contacts the Heat Roll. If the surface of the Thermistor is
worn, replace the Heat Roll Overheat Thermistor (PL 8.4). Inspect the surface of the Heat
Roll for excessive wear due to the Thermistor. Replace the Heat Roll if necessary (PL
8.3).
• Check the Drawer connector P700B at the rear of the Fuser for damaged pins. Check the
mating connector on the IOT, and ensure that the mounting plate for the IOT connector is
not bent or misaligned.
Procedure
NOTE: Prior to replacing a component, disconnect the connectors to the component (Heat Roll
Overheat Thermistor and IOT Drive PWB). Check the connectors for broken, bent and dirty
pins. Disconnect and reconnect the connectors several times to remove contaminants due to
oxidation.
Switch the power off. Disconnect P/J172 on the Heat Roll Overheat Thermistor. Measure the
resistance between P/J172-1 and P/J172-2 on the Heat Roll Overheat Thermistor. The resistance
of the Thermistor should be in the range of 0.78K Ohms when hot to 150K Ohms when
cool (room temperature). Note the measurement if it is in specification. The resistance of the
Thermistor is in specification.
NO: Replace the Heat Roll Overheat Thermistor (PL 8.4).
Reconnect P/J172 to the Heat Roll Overheat Thermistor. Close the Drawer. Disconnect P/
Yes: J413A from the IOT Drive PWB. Measure the resistance from P/J413A-13 to P/J413A-8. The
resistance measurement is the same as the measurement noted above (+/- 5%).
No: Go to Flag 1 and Flag 2 on BSD 10.2. Check the harness for an open circuit.
Yes: Replace the IOT Drive PWB (PL 9.2).