HP P 1100 Service Manual

							Image formation process
Each of the following process function independently and must be coordinated with the other product
processes. Image formation consists of the following processes:
●Latent-image formation block
◦Step 1: primary charging
◦ Step 2: laser-beam exposure
● Developing block
◦Step 3: developing
● Transfer block
◦Step 4: transfer
◦ Step 5: separation
● Fusing block
◦Step 6: fusing
● Drum cleaning block
◦Step 7: drum cleaning
Figure 1-15   Image formation process
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							Latent-image formation stage
During the latent-image formation stage, the laser/scanner forms an invisible image on the
photosensitive drum in the print cartridge.
Primary charging Step 1: dc and ac biases are applied to the primary charging roller, which transfers a uniform negative
potential to the photosensitive drum.
Figure 1-16   Primary charging
DC bias
Photosensitive drum
Primary charging roller
Laser beam exposure
Step 2: The laser beam scans the photosensitive drum to neutralize negative charges on parts of the
drum surface. An electrostatic latent image is formed on the drum where negative charges were
neutralized.
Figure 1-17   Laser beam exposure
Laser beam
Unexposed area Exposed area
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							Developing stage
Print cartridgeStep 3: In the print cartridge, the developing cylinder transfers toner onto the electrostatic latent image
on the photosensitive drum.
Figure 1-18   Print cartridge
Blade
Developing cylinder
AC bias
DC bias
Photosensitive drum
Unexposed area
Exposed area
Exposed area
Unexposed area
Toner acquires a negative charge from the friction that occurs when the developing roller rotates against
the developing blade. The developing bias is applied to the developing roller to make a potential
difference between the developing roller and the photosensitive drum. The negatively charged toner is
attracted to the latent image on the photosensitive drum because the drum surface has a higher
potential.
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							Transfer stage
Step 4: The transfer charging roller, to which a DC positive bias is applied, imparts a positive charge
on the paper. When the paper comes in contact with the photosensitive drum, the toner is transferred
to the paper.
Figure 1-19   Transfer
Media
Transfer roller Photosensitive
drum
DC bias
Step 5 : The elasticity of the paper causes its separation from the photosensitive drum. A static charge
eliminator aids separation by weakening any electrostatic adhesion.
Figure 1-20   Separation
Media
Transfer roller
Photosensitive
drum
Static charge eliminator
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							Fusing stageStep 6: The DC negative bias applied to the fusing film strengthens the holding force of the toner on the
paper and prevents the toner from scattering.
The product uses an on-demand fuser method. The toner image is permanently affixed to the paper by
heat and pressure.
Figure 1-21   Fusing
Fuser film
Toner 
Pressure roller 
Fuser heater
Media 
Cleaning stageStep 7: The cleaning blade scrapes the residual toner off of the photosensitive drum and deposits it into
the waste toner case.
Figure 1-22   Drum cleaning
Waste toner container Photosensitive
drum
Cleaning blade
ENWW
Image-formation system 27 
						

							Pickup, feed, and delivery system
The media feed system picks up, feeds, and delivers the page.
Figure 1-23  Pickup, feed, and delivery system block diagram
Fuser film
Delivery roller
Single-sheet-feed slot
(HP LJP P1100w printer Series)
Transfer roller
Photosensitive drum
Feed roller Pickup roller
Separation
pad
Pressure roller
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							Photo sensors and switches
NOTE:The illustration in this section also shows the product motor and solenoid. The power switch
is not shown.
Figure 1-24   Photo sensors, motor, and solenoid
M1
PS751
PS701
PS702
SL1
Single-sheet-feed slot
(HP LJP P1100w printer Series)
Table 1-7   Photo sensors, motor, and solenoid
ItemDescription
M1Main motor
SL1Pickup solenoid
PS701Fuser delivery sensor
PS702Media-width sensor
PS751TOP sensor
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							Input tray, main-input tray, or priority input slot
NOTE:The HP LaserJet Professional P1100 Printer series has a single input tray. The HP LaserJet
Professional P1100w Printer series has a main-input tray and a priority input slot.
Jam detection
The product uses the following sensors to detect the presence of paper and to check for jams. The paper
must pass each sensor within a specified time.
NOTE: To find the following components, see Photo sensors and switches on page 29.
● PS701; fuser delivery sensor
● PS702; TOP sensor
NOTE:
The product automatically ejects paper if the TOP sensor detects residual paper within
the product when the power is turned on or the door is closed.
The product detects the following jams:
● Pickup stationary jam
● Delivery delay jam
● Delivery stationary jam
● Fuser wrapping jam
● Door open jam
● Residual media jam
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							2 Removal and replacement
●Introduction
●
Removal and replacement strategy
●
Electrostatic discharge
●
Required tools
●
Before performing service
●
After performing service
●
Post-service test
●
Parts removal order
●
Pickup roller
●
Separation pad
●
Transfer roller
●
Covers
●
Main assemblies
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							Introduction
This chapter describes the removal and replacement of field-replaceable units (FRUs) only.
Replacing FRUs is generally the reverse of removal. Occasionally, notes and tips are included to provide
directions for difficult or critical replacement procedures.
HP does not support repairing individual subassemblies or troubleshooting to the component level.
Note the length, diameter, color, type, and location of each screw. Be sure to return each screw to its
original location during reassembly.
Incorrectly routed or loose wire harnesses can interfere with other internal components and can become
damaged or broken. Frayed or pinched harness wires can be difficult to find. When replacing wire
harnesses, always use the provided wire loops, lance points, or wire-harness guides and retainers.
Removal and replacement strategy 
WARNING! Turn the product off, wait 5 seconds, and then remove the power cord before attempting
to service the product. If this warning is not followed, severe injury can result, in addition to damage to
the product. The power must be on for certain functional checks during troubleshooting. However,
disconnect the power supply during parts removal.
Never operate or service the product with the protective cover removed from the laser/scanner
assembly. The reflected beam, although invisible, can damage your eyes.
The sheet-metal parts can have sharp edges. Be careful when handling sheet-metal parts.
CAUTION: Do not bend or fold the flat flexible cables (FFCs) during removal or installation. Also, do
not straighten pre-folds in the FFCs. You  must fully seat all FFCs in their connectors. Failure to fully
seat an FFC into a connector can cause a short circuit in a PCA.
NOTE: To install a self-tapping screw, first turn it counterclockwise to align it with the existing thread
pattern, and then carefully turn it clockwise to tighten. Do not overtighten. If a self-tapping screw-hole
becomes stripped, repair the screw-hole or replace the affected assembly.
TIP: For clarity, some photos in this chapter show components removed that would not be removed
to service the product. If necessary, remove the components listed at the beginning of a procedure
before proceeding to service the product.
32 Chapter 2   Removal and replacement ENWW