Gp 3.7 Fuser Control - Xerox N2125N - DocuPrint B/W Laser Printer Service Manual

• Warm-up failure - SOS signal intervals are longer than the READY reference value during
three consecutive samplings of the SOS. The actual laser power does not equal the value
set in NVRAM.
• Laser speed too low (Down Failure) - SOS signal intervals are longer than the set Down
Failure interval after completion of warm-up. The set Down Failure is a time interval corre-
sponding to 90% of the rated Laser Motor speed of rotation.
• Laser speed too high (Overrun Failure) - SOS signal intervals are shorter than the set
Overrun Failure interval after completion of warm-up. The set Overrun Failure is a time
interval corresponding to 102% of the rated Laser Motor speed of rotation.
Initial Issue
DocuPrint N2125

GP 3.7 Fuser Control

Fuser Temperature Control
The Thermistor monitors the temperature on the surface of the Heat Roll and compares that
temperature with the rated temperature that was set in NVRAM. The Print Engine Controller
switches the Heat Rod on or off depending on how the actual temperature differs from the rated
temperature.
Fuser Temperature Adjustment
You can adjust the rated Fuser temperature by changing the NVRAM Value. You can adjust the
setting in 16 increments, with each increment approximately 4 C.
The printer switches on the Heat Rod when the Fuser temperature lowers below the current
control temperature (approximately 178 C for the standard control temperature). The printer
switches off the Heat Rod when the Fuser temperature rises above the current control temper-
ature (approximately 180 C for the standard control temperature).
Fuser Warm-up
Power to the Heat Rod is applied at the start of printer warm-up. Warm-up is complete when
the Heat Roll reaches the current control Temperature. If the Fuser Temperature is below
100 C at start of warm-up, then warm-up finishes when the Fuser temperature reaches
"standby temperature".
Fuser Trouble (U4 Error Code)
There are five major causes of a U4 error.
• Warm-up failure - Fuser warm-up does not complete within specified seconds after start-
ing.
• Low Trouble temperature - The Fuser temperature drops to the Low Trouble temperature
(approximately current control temperature, minus approximately 25 C
• High Trouble temperature -The Fuser temperature rises to the High Trouble temperature
(approximately current control temperature, plus approximately 35 C
• The Thermistor circuit opened.
• STS failure -The Heat Rod remains on for at least ten seconds after warm-up has com-
pleted.
AC Power Shutoff to the Fuser
There are eight reasons that the printer shuts off AC power to the Fuser.
• Fuser Failure (U4)
• Paper jam
• Open Front Cover Assembly
• Laser failure (U2)
• CPU or NVRAM problem (U6)
• Main Motor Assembly problem (U1)
• Fan problem (U5)
02/2000
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General Procedures / Information
GP 3.6 , GP 3.7