Lexmark Optra C710 Service Manual - Page 123

5016-001 Fuser Hot Service Check CAUTION: The fuser may be hot, use caution before removing or servicing. Error Codes 923 and 924 may display for a hot fuser failure. Error Code 924 indicates the engine board has detected an open in the thermistor circuit. Note: Most of the wiring and electrical devices can be reached by removing the paper exit cover on the bottom of the fuser assembly. FRU 1 Fuser: • Assembly • Hot Roll • Backup Roll Bearings 2 Thermistor Assembly Engine Board Action Check the fuser assembly for signs of overheating or damage, especially the hot roll and backup roll. Also check for contaminants such as label glue or excessive toner buildup. • If contaminants are found, repair as necessary or replace the fuser assembly. • If damage from overheating is found, replace the fuser. Check for a shorted thermistor by measuring across the connector located in the cable guide. • If the thermistor is shorted, replace the thermistor. • If replacing the failing thermistor does not fix the problem, replace the engine board. Check for signs of damage or contamination to the thermistor assembly. If no problem is found, check the resistance of the thermistor. Hot: CN18-1 to CN18-2: Approximately 2.0k - 2.5k ohms Cold: Approximately 150k to 250k ohms If incorrect, replace the thermistor. Check for an open in the thermistor circuit in the fuser assembly. Be sure the thermistor is properly connected to the thermistor cable in the bottom of the cable guide. Diagnostic Information 2-57