Hot Fuser Service Check - Lexmark T632 Service Manual

4060-xxx

Hot fuser service check

Error Code 923: Indicates the fuser is too hot during printing or when the printer is idle.
Error code 924: Indicates an open circuit has been detected in the fuser thermistor circuit.
Note: Check the fuser sub error codes to help diagnose between a 923 and 924 error.
CAUTION: The fuser may be hot, use caution before removing or servicing.
CAUTION: There is a danger from hazardous voltage in the area of the printer where you
are working. Unplug the printer before you begin, or use caution if the printer must receive
power in order to perform the task.
FRU
1 Fuser cover assembly
(assembly includes
thermistor and thermal
fuses)
2 Fuser assembly
3 Fuser to system board DC
cable
4 System board
5 Fuser hot roll
Fuser hot roll bearings
Fuser backup roll bearings
Fuser backup roll
Fuser mechanical parts
2-54
Service Manual
Action
Check for damage to the thermistor assembly. If damage is found,
replace the fuser top cover assembly. If no damage is found, check
the resistance of the thermistor between pins J6-1 and J6-2 on the
cable.
• HOT < 10K ohms
• COLD = approximately 450K ohms
If the resistance is incorrect, replace the fuser top cover assembly. If
the resistance is correct, check each pin of J6 to ground. If there is
continuity, replace the fuser cover assembly. See
removal" on page 4-25.
Check for continuity between J6-1 and J1-2 and between J6-2 and
J1-3. If incorrect, replace the fuser assembly. If correct, go to step 3.
Check the continuity of the cable. If incorrect, replace the cable. If
correct, go to step 4.
Measure the voltage on J14-3 on the system board. The voltage
should change from approximately +2.5 V dc with the thermistor cold
to approximately +1.6 V dc when the thermistor is hot. If incorrect,
replace the system board. If correct, go to step 5.
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 problems are found, replace the
fuser assembly.
"Fuser cover