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Service Guide OL400
Chapter 4 Failure & Repair Analysis
RAP 05:Engine Error - Fusing Problem Alarm
START
Turn the power OFF, then ON. Does a fuser unit alarm occur immediately?
NO
Go to A
YES
Is the thermistor open (the normal resistance should be about 100k ohms
at room temperature)? Measure between pins 1 and 2 of the cable connected to
engine controller circuit board J2.
YES
Replace the fuser assembly.
NO
Is the thermistor shorted? (See above)
YES
Replace the fuser assembly.
NO
Replace the engine controller circuit board.
END
A
Power OFF, then ON.
Does the fuser lamp glow? (Check this from the rear vents of the printer.)
YES
Is the thermistor open? (See above)
NO
Replace the engine controller circuit board.
YES
Replace the fuser assembly.
NO
Is the fuser lamp open? (With the upper cover open, lift the upper unit
and
measure the resistance between the heater AC connections.) (0
ohms is
normal. Infinite resistance is open.) Check for proper
contact between the
fuser's AC contacts and the power supply.
YES
Replace the fuser assembly.
NO
Is the HEAT signal turned on? (HEAT signal at engine controller
circuit board IC3 pin 75.)
NO
Replace the engine controller circuit board.
YES
Replace the power supply unit.