3-30 Phaser 7750 Printer Service Manual
Fuser STS (Rear) Failure, Code 45
Rear Thermistor open error. The machine logic detected an open circuit in the rear
thermistor.
Troubleshooting References
Applicable Parts Wiring and Plug/Jack Map References
■ Fuser
■ Engine Control Board
Troubleshooting Procedure
Step Actions and Questions Yes No
1
1. Turn OFF power, remove the fuser
assembly and allow it to cool down.
2. Measure the resistance between the
Fuser connector P600-7 and P600-9.
3. Does the resistance measure between
30 K and 190 K Ohms?
Go to step 2. Replace the fuser
assembly.
2
1. Reinstall the fuser assembly.
2. Enter service diagnostics.
3. From the Sensor Tests run the Fuser
Temperature test.
4. Is the temperature indicated
approximately 165
o
C?
Replace the
engine control
board.
Go to step 3.
3
1. Turn printer power OFF.
2. Check for an open circuit or poor
connection between J641-4 and
J641-5.
3. Is the wiring harness OK?
Replace the
engine control
board.
Repair or replace
the wiring
harness.
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