Lexmark T620 Service Manual - Page 95

4069-5XX/7XX Hot Fuser Service Check Error codes 923 and 924 may display for a hot fuser failure. CAUTION: The fuser may be hot, use caution before removing or servicing. FRU 1 Fuser Cover Assembly (Assembly includes Thermistor and Thermal Fuses.) 2 System Board 3 Fuser Hot Roll Backup Roll Bearings Action Check for damage to the thermistor assembly. Check the resistance of the thermistor: HOT - J2-1 to J2-2 = 2.5K ohms COLD =150K ohms to 260K ohms If the resistance is incorrect, replace the fuser cover assembly. Error code 924 indicates the system board detects an open circuit in the thermistor circuit for the fuser assembly. The voltage on J14-6 on the system board measures approximately +5 V dc. If incorrect, replace the system board. If correct, check the continuity of the DC fuser cable in the fuser assembly and the DC fuser cable (system board to auto docking connector) attached to J14 on the system board. If there is no continuity, replace the cable. Examine the fuser assembly for signs of overheating or damage. Check the hot roll and backup roll for signs of excessive toner, label glue, labels or other contaminants. If any are found, repair as necessary or replace the fuser assembly. Diagnostic Information 2-67