Xerox 3150 - Phaser B/W Laser Printer, Service Manual

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Summary of Product
Service Manual 4-11
4.3.5.9 Transfer
The charging voltage, developing voltage, and the transfer voltage are controlled by pulse width modulation (PWM).
Each output voltage is changeable according to the PWM duty cycle. The transfer voltage used when the paper passes
the transfer roller is decided by environment recognition. The resistance value of the transfer roller changes due to the
environment of the room or within the printer. This change in resistance in turn changes the value of the voltage due
to loading. This voltage is fed back into the printer through the A/D converter. Based on the value fed back the PWM
cycle is changed to maintain the required transfer voltage.
4.3.5.10 Fusing
The temperature of the heat roller's surface is detected according to the resistance value of the thermistor. The
thermistor resistance is measured using the A/D converter and thus the CPU can determine the temperature of the heat
roller. 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 controlled range while controlling the fusing process, an error is reported.
See the error table below to identify fuser temperatur errors.
4.3.5.11 Laser Scanner Unit (LSU)
The Laser Unit consists of the laser diode and the polygon motor control. When the printing signal occurs, the laser
diode is turned on and the polygon motor is enabled. When the light sensor detects the beam, H-SYNC occurs. When
the polygon motor speed becomes steady, Ready mode occurs. If these two conditions are satisfied the laser unit is
judged to be ready. If the two conditions are not satisfied, one of two errors are reported as shown in the table below.
Error Description DCU LED Display
Open heat error
Lower than 68
0
C for more than 25 seconds while
warming up.
60 All LEDs blinking
Low heat error Standby:
Lower than 100
0
C for more than 20 seconds.
Printing:
From 2 consecutive pages; the fixed fusing
temperature has been lower than 30
0
C for more
than 5 seconds.
Higher than 220
0
C for over 3 seconds.
62 All LEDs blinking
Over heat error
It has been higher than 220
0
C for over 3 seconds.
68 All LEDs blinking
Error Description DCU
Polygon motor error When the polygon motor speed is not steady. 95
H-SYNC error The polygon motor speed is steady but the H-SYNC
is not generated. 96