Canon LBP 2460 Service Manual - Page 254

Malfunction Troubleshooting, M-1 Fixing Unit Failure Abnormal Temperature, Action

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CHAPTER 4 B. Malfunction Troubleshooting M-1 Fixing Unit Failure (Abnormal Temperature) 1. The thermistor has shorted. Action: Turn the power OFF and remove the fixing unit. Measure the resistance between the fixing unit connector J50B-2 (FSRTH) and J50B-3 (GNDTH). The connector J50B is the lower terminal of the left connector. If the resistance is 1kΩ or less, check the wiring from connector J222 on the DC controller PCB to the thermistor. If it is normal, replace the thermistor. 2. The fixing unit drive circuit in the power supply is defective. Action: Replace the power supply. 3. The DC controller PCB is defective. Action: Replace the DC controller PCB. M-2 Fixing Unit Failure (abnormal Warm-up failure/abnormal low temperature) 1. The thermistor is dirty. Action: If the thermistor contact area of the fixing upper roller is dirty, clean it. 2. The thermistor is not installed correctly. Action: If the thermistor is not evenly contacting the fixing upper roller, re-install the thermistor correctly. 3. The thermistor wire is broken. Action: Turn the power OFF and remove the fixing unit. Measure the resistance between the fixing unit connector J50B-2 (FSRTH) and J50B-3 (GNDTH). If the resistance is not between 150kΩ and 290kΩ (normal temperature), check the wiring from connector J222 on the DC controller PCB to the thermistor. If it is normal, replace the thermistor. 4. The main heater wire is broken. Action: Remove the fixing unit. If there is no continuity between the fixing unit connector J50-3 (FSRN1: the upper right terminal of the left connector) and J51-4 (FSRN2: the upper right terminal of the right connector), replace the main heater. 5. The sub heater wire is broken. Action: Remove the fixing unit. If there is no continuity between the fixing unit connector J50-4 (FSRL1: the lower right terminal of the left connector) and J51-3 (FSRL2: the lower right terminal of the right connector), replace the sub heater. 6. The thermoswitch is open. Action: Remove the fixing unit and wiring cover. If there is no continuity between thermoswitch connectors, replace the thermoswitch. 7. The DC controller PCB is defective. 4 - 40

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B.
Malfunction Troubleshooting
M-1 Fixing Unit Failure (Abnormal Temperature)
<Possible causes>
1.
The thermistor has shorted.
Action:
Turn the power OFF and remove the fixing unit.
Measure the resistance between the
fixing unit connector J50B-2 (FSRTH) and J50B-3 (GNDTH).
The connector J50B
is the lower terminal of the left connector.
If the resistance is 1k
Ω
or less, check the
wiring from connector J222 on the DC controller PCB to the thermistor.
If it is
normal, replace the thermistor.
2.
The fixing unit drive circuit in the power supply is defective.
Action:
Replace the power supply.
3.
The DC controller PCB is defective.
Action:
Replace the DC controller PCB.
M-2 Fixing Unit Failure (abnormal Warm-up failure/abnormal low temperature)
<Possible causes>
1.
The thermistor is dirty.
Action:
If the thermistor contact area of the fixing upper roller is dirty, clean it.
2.
The thermistor is not installed correctly.
Action:
If the thermistor is not evenly contacting the fixing upper roller, re-install the
thermistor correctly.
3.
The thermistor wire is broken.
Action:
Turn the power OFF and remove the fixing unit.
Measure the resistance between
the fixing unit connector J50B-2 (FSRTH) and J50B-3 (GNDTH).
If the resistance
is not between 150k
Ω
and 290k
Ω
(normal temperature), check the wiring from
connector J222 on the DC controller PCB to the thermistor.
If it is normal, replace
the thermistor.
4.
The main heater wire is broken.
Action:
Remove the fixing unit.
If there is no continuity between the fixing unit connector
J50-3 (FSRN1: the upper right terminal of the left connector) and J51-4 (FSRN2: the
upper right terminal of the right connector), replace the main heater.
5.
The sub heater wire is broken.
Action:
Remove the fixing unit.
If there is no continuity between the fixing unit connector
J50-4 (FSRL1: the lower right terminal of the left connector) and J51-3 (FSRL2: the
lower right terminal of the right connector), replace the sub heater.
6.
The thermoswitch is open.
Action:
Remove the fixing unit and wiring cover.
If there is no continuity between
thermoswitch connectors, replace the thermoswitch.
7.
The DC controller PCB is defective.
CHAPTER 4
4 - 40