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HP P 1100 Service Manual

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Page 31

Fuser failure detection
The DC controller determines a fuser unit failure, releases the relay to interrupt power supply to the
fuser heater, and notifies the formatter of a failure state when it encounters the following conditions:
●Start up failure
◦If the main thermistor does not detect a specified temperature during the start up process of
the heater in the wait period.
◦ If the main thermistor does not detect a specified temperature during the heater temperature
control in the initial rotation...

Page 32

Fuser temperature control
The fuser temperature control maintains the temperature of the fuser heater at its targeted temperature.
The DC controller monitors the FIXING TEMPERATURE (FSRTH) signals and sends the FIXING
HEATER CONTROL (FSRD) signal according to the detected temperature. The fuser heater control
circuit controls the fuser heater depending on the signal so that the heater remains at the targeted
temperature.
Figure 1-9  Fuser-heater control circuit
FSRTH DC controller
RLYD
FREQSNS
AC input...

Page 33

Fuser protective function
The protective function detects an abnormal temperature rise of the fuser unit and interrupts power
supply to the fuser heater.
The following three protective components prevent an abnormal temperature rise of the fuser heater:
●DC controller
◦The DC controller interrupts power supply to the fuser heater when it detects an abnormal
temperature of the fuser heater.
● Fuser heater safety circuit
◦The fuser heater safety circuit interrupts power supply to the fuser heater when the...

Page 34

Low-voltage power supply
The low-voltage power supply (LVPS) converts ac input voltage to dc voltage. The LVPS has two fuses
on the PCA. The LVPS 24 V output is interrupted to the fuser and the high-voltage power supply if the
cartridge-door interlock switch (SW501) is in the off position (cover open).
WARNING!The product power switch only interrupts dc voltage from the LVPS. The ac voltage is
present in the product when the power cord is plugged into a power receptacle and the power switch is
in the off...

Page 35

Overcurrent/overvoltage protection
The low-voltage power supply has a protective function against overcurrent and overvoltage to prevent
failures in the power supply circuit. If an overcurrent or overvoltage condition occurs, the system
automatically cuts off the output voltage.
If the dc power is not being supplied from the low-voltage power supply, the protective function might
be running. In such case, turn off the power switch and unplug the power cord. Do not plug in the power
cord or turn on the...

Page 36

High-voltage power supply
The high-voltage power supply (HVPS) applies biases to the following components:
●Primary charging roller
● Developing roller
● Transfer roller
Figure 1-11   High-voltage power supply
Primary
charging bias circuit
Developing
bias circuit
Transfer bias circuit
Engine controller
To primary charging roller
To developing roller
Photosensitive drum
Transfer roller
High-voltage power supply
DC controlle r
Cartridge
18 Chapter 1   Theory of operation ENWW 

Page 37

Laser/scanner system
The laser/scanner system receives VIDEO signals from the ECU and formatter and converts the signals
into latent images on the photosensitive drum.
The main components of the laser/scanner are the laser unit and the scanner motor unit. The DC
controller sends signals to the laser/scanner to control the functions of these components.
Figure 1-12  Laser/scanner system
Formatter
DC controller
BDI signal
VIDEO signal
LASER CONTROL signal 
 
SCANNER MOT OR CONTROL signal
Engine controller...

Page 38

Laser failure detection
The DC controller determines an optical unit failure and notifies the formatter, if the laser/scanner
encounters the following conditions:
●The scanner motor does not reach a specified rotation within a specified period of the scanner
motor start up.
● The rotation of the scanner motor is out of specified range for a specified period during the scanner
motor drive.
● The BD interval is out of a specified value during a print operation.
20 Chapter 1   Theory of operation ENWW 

Page 39

Image-formation system
Electrophotographic process
The electrophotographic process forms an image on the paper. Following are the major components
used in the process:
●Print cartridge
● Transfer roller
● Fuser
● Laser/scanner
● High-voltage power supply
The DC controller uses the laser/scanner and HVPS to form the toner image on the photosensitive drum.
The image is transferred to the paper and then fused onto the paper.
Figure 1-13   Electrophotographic process block diagram (1 of 2)
High-voltage power...

Page 40

Figure 1-14  Electrophotographic process block diagram (2 of 2)
DC controlle r
Engine controller
Cartridge
Transfer roller Developing roller
Main motor
Photosensitive drum Primary charging roller
22 Chapter 1   Theory of operation
ENWW 
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