Xerox Phaser 3450, Service Manual, Page: 27 / 155

4-15
Summary of product
Service Manual
4.4.4 Fusing
The temperature change of the heat roller’s surface is changed to the resistance value through the thermistor. By con-
verting the voltage value, which impressed to the resistance, to the digital value through the AD converter, the temperature
is decided. The AC power is controlled by comparing the target temperature to the value from the thermistor. If the value
from the thermistor is out of the controlling range while controlling the fusing, the error stated in the table occurs. (For the
domestic model, the Q-PID method has been applied.)
4.4.5 LSU
The LSU is consisted of the LD (Laser Diode) and the polygon motor control. When the printing signal occurs,
it turns the LD and drives the polygon motor. When the receiving light part detects the beam, Hsync occurs.
When the polygon motor speed becomes a normal, LReady occurs. If two conditions are satisfied, the sta-
tus bit of the LSU controller register becomes 1 to be judged that the LSU is ready. If two conditions are not
satisfied, the error shown in below occurs.
Error Description LCD Displat
Open Heat Error When warming up, it has been lower Engine Fuser Error
than 68°C over 28 seconds
Lower Heat Error • Standby : Engine Fuser Low Heat Error
It has been lower than 130°C over 10 seconds
• Printing :
- 3 consecutive page; it has been 20°C lower
than the fixed fusing temperature over 7 seconds.
Over Heat Error It have been higher than 230°C over 10 seconds Engine Fuser Over Heat Error
Error Description LCD
Polygon motor error When the polygon motor’s speed doesn’t Photo Error
become a normal
Hsync error The polygon motor’s speed is normal, HSYNC Error
but the Hsync signal is not created.