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Transcript of 45xx PQ Guide
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
Resolving Print Quality Defects
Consumables account for most print quality issues. Do not replace any hardware parts until you have ensured a consumable is not the source of the
print quality issue.
It is important to understand the EP process before embarking on PQ troubleshooting. A brief recap on the CLJ4500/4550 EP process is:1. The Primary Charge roller inside the imaging drum charges the OPC drum to approximately -600v.
2. The laser beam selectively discharges the OPC drum.3. Blackis developed onto the OPC drum first, then immediately transferred to the ITB.4. Magenta, Cyan, and Yellow are then developed (in that order), using the same process as black.
5. Once all 4 color planes have been transferred to the ITB, the image on the ITB is transferred to the paper via the secondary transfer roller.
Note on Lines / Banding / Streaking PQ issues:
It is important when addressing these issues to understand the paper verses banding orientations correct. Figure 1: Horizontal and vertical banding (The arrows for both pictures in Figure 1 indicate the process direction (or paper movement).
1- Horizontal banding (perpendicular to the process direction)
2- Vertical banding (parallel to the process direction)
Repetitive Defect Distances
Consumable Roller Distance
Image Drum Charge Roller 40mm (1.6 inches)OPC Drum 152mm (6 inches)
Toner Cartridges Black 37mm (1.5 inches)
Color 30mm (1.2 inches)
Fuser 131mm (5.2 inches)
ITB ICL Roller 40mm (1.6 inches)
Transfer Roller 53mm (2.1 inches)
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References to additional information
Several PQ issues mentioned in this guide are documented with greater detail in the Knowledge
Retrieval System (KRS).
To receive a login and password for KRS, contact ICO Technical Marketing at the following URL:
http://techweb.boi.hp.com/
Note: Several PQ defects are caused by 3rd-party / remanufactured cartridges. Refer to BPL10795
for complete information on identifying 3rd-Party cartridges.
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Blank Pages
DescriptionAll printouts, including printer test pages, exit the printer blank
Possible Causes Blocked laser shutter
The imaging drum is not rotating
The imaging drum shutter is not retracting
Defective ITB (if blank pages print continuously withoutstopping).
Defective drum drive assembly
Troubleshooting and Suggestions Disconnect the printer from the network before troubleshooting.
Check the tab on the imaging drum (See BPL90006, Figure 1 for
the location). Verify that it is present.
Check to see if white gear on the drum drawer is present (See
BPL90006, Figure 2 for the location).
Check service note C4084A-11 for troubleshooting a possibledefective ITB.
Recommended Parts ITB
White gear
HVPS
Imaging Drum
Carousel drive assembly
Drum Drive assembly
IMPORTANT NOTE: This issue is covered in a work
instruction. See document BPL90006. See service noteC4084A-11 for the defective ITB issue.
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Toner Dusting/Leaking
Description
Spots and small blobs of one of more than one toner color
appear on the printed page. Spots may also appear on theback side of print jobs.
Possible CausesToner dusting occurs when toner particles migrate from the toner
cartridges and deposit on the flaps that cover the toner cartridges. The
CMY cartridges use a non-magnetic toner that relies on static charging
to hold the particles in place. Many times, customers have cartridgesthat extend beyond the stated 6,000-page life. As a result, some of the
toner particles become "worn" and lose their ability to hold a charge.These particles can then fly away from the toner cartridge as toner dust
and deposit on the flaps.
Sometimes toner dust will build up on the toner cartridge itself, then
fall onto the transfer roller. As media passes over the transfer roller,
this toner is picked up and appears as spots that repeat and fade downthe page. The printer performs a cleaning cycle that removes toner
from the transfer roller, but it may not clean the roller entirely.
Troubleshooting and suggestions
Clean the transfer roller with a lint-free cloth
Clean out the waste toner collection tray
Check for 3rd party cartridges. (See BPL10795).
Replace the leaking cartridge(s)
Recommended PartsToner cartridge(s)
Toner cloths
Transfer roller(optional)
IMPORTANT NOTE: This PQ defect is covered in a work
instruction. See BPL90013.
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Toner Flaking
Description
Toner has flaked off the printed page and may be re-deposited
on other parts of the page. (The example shown here was aletter-sized label).
Possible Causes
The media is not within specifications. (Media is
heavier than then what is supported by the printer.
Toner may build up on the fuser and redeposit on the
next page.Troubleshooting and Suggestions
Verify that the media is within specifications
Recommended Parts
Fuser(optional) if it has been damaged by repeated use of
unsupported media.
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Smeared Print
Description
The printed image is smeared and may appear faded or diluted.
Possible Causes
Jammed media in or around the ITB, imaging drum, transfer roller, or fuser. (See
Figure 1).
The frame above the ITB cleaning roller has been bent, causing the cleaning roller
to push against the ITB belt every couple of inches. (See Figure 2).
Troubleshooting and Suggestions
Check the ITB for abrasion marks.
Check the ITB ICL roller for damage or for jammed media like an adhesive label.
Check for jammed media underneath the ITB's top cover.
Check for a damaged ITB (bent ITB frame).
Recommended parts
ITB
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Full-page Ghosting
Description
Entire images from the previous page "ghost" on the current page. In
this example, the Configuration page is ghosting on the EIO 1Configuration page.
Possible Causes
A defective ITB may cause the issue (most common).
3rd-Party Cartridges
The three high-voltage contacts on the middle front drawer
may be damaged or missing contacts (springs).
The cleaning roller cam clutch (CL3) is not engaging.
A failing High-Voltage Power Supply (HVPS) may cause this
issue due to improper charging of the ITB cleaning roller.
Site power. (Plug the printer directly into the wall).
Troubleshooting and suggestions
Check the media.
Check the humidity and temperature.
Check the electrical connections in the middle front drawer.
Check the face plate and the cam shaft for CL3.
Recommended Parts
See BPL90043 for recommended parts.
IMPORTANT NOTE: This PQ defect is covered in a work
instruction. See document BPL90043.
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Same page ghosting in a 40mm band(Process Direction)
Description
Ghosted images at a 40mm interval print down the page in theprocess direction. Color or black may ghost.
Possible Causes
The ITB ICL roller cam assembly may not reset normally,
causing the alignment marks not to align correctly.
Troubleshooting and Suggestions Measure the ghosted images with a PQ defects ruler.
Check for a label wrapped around the ICL roller.
Check the position of the alignment marks on the CL3
cam shaft. (The alignment marks should face out).
Recommended Parts Transfer kit
CL3
IMPORTANT NOTE: This PQ defect is covered in a work
instruction. See document BPL90043.
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Black Developer Ghosting (37mm)(Process Direction)
Description
Images repeat (ghost) down the page in 37mm increments,which matches the circumference of the developer sleeve on
the black toner cartridge.
Possible Causes
When printing a heavy black or solid dark color, the negative
charge that has been applied to the imaging drum cannot be
cleared quickly enough to eliminate the heavy toner buildup.The heavier the contrast between the solid image and the
background, the stronger the ghost image will appear and the
more often it will repeat.
Troubleshooting and Suggestions
Avoid using heavy concentrations of color against a
lighter, contrasting background
Move the solid image so a shaded area is not below it
Change the density of the shaded area
Recommended Parts
None
IMPORTANT NOTE: This issue is covered in KRSII. See
BPL11041 for complete details.
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Magenta or Black-Only Ghosting
Description
This defect appears as a streak of color down the page aftermagenta is laid down. It is best seen after printing three or
more consecutive font lists.
Possible Causes
The ITB cleaning roller is not applying enough positive
charge on the residual toner to carry the toner to the imaging
drum surface for cleaning. Refer to Service Note C4084A-12for complete details.
Troubleshooting and Suggestions
Print 20-100 consecutive color pages. (If the ghosting does not
disappear, replace the ITB).
Check the lot code on the ITB. A counter measure ITB is now
available. The lot code for the new ITBs are EGBXXXXXXX
or later.
Recommended Parts
ITB
IMPORTANT NOTE: This issue is covered in a work
instruction. See document BPL90043. Also see Service Note
C4084A-12.
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Same Page Positive Ghosting
Description
This issue appears as a dark shadow (ghost) in areas of lightgray on light half-tone colored backgrounds. The ghost image
repeats itself every 152 mm (6 inches).
Possible Causes
When the imaging drum is near the end of its life cycle, the
customer may start to see positive ghosting.
Troubleshooting and Suggestions
Changing the background color or tone in the application can
help resolve this issue.
Recommended PartsImaging drum
IMPORTANT NOTE: This issue is covered in a work
instruction. See document BPL90043.
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Same Page Negative Ghosting
Description
This issue appears when dark images from one part of a pageare repeated as light ghosting in areas of medium gray or
medium halftone colored backgrounds. The ghost image
repeats itself every 152 mm (6 inches).
Possible Causes
After a new imaging drum is installed, the customer may seenegative ghosting. As the drum life progresses, the ghost image
may go away.
Troubleshooting and Suggestions
Change the background color or tone.
Recommended PartsNone
IMPORTANT NOTE: This issue is covered in a work
instruction. See document BPL90043.
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CMYK Spots (6mm apart)(Process Direction)
Description
Rows of Cyan, Magenta, Yellow, and Black (CMYK) dotsprint down the page in the process direction. The distance
between the dots is 6mm. The dots may also appear to be gray
or black. In one version, the distance between the dot of a
given color and the next of the same color is observably
152mm or about 6 inches from one dot to the next dot of the
same color.
Possible Causes
A nick or scratch has been made on the imaging drum
Troubleshooting and suggestions
Replace the imaging drum. (This will be the customer's
responsibility unless the drum is new).
Recommended parts
Imaging drum
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White Gapping
Description
This issue appears as a white line or gap, one or two pixels in width,
that surrounds filled areas of text. (Note the white gapping underneaththe eagle's wings).
Possible Causes
There is no hardware fix for this issue
Using halftone colors
Variations in line widths
Polarization within the chemical composition of the toners
Troubleshooting and Suggestions
Use the PCL driver
Change or alter the colors exhibiting white gapping
Avoid using halftone colors
Remove black borders or frames around a solid fill color
Adjust the registration numbers. (See Chapter 7 in the service
manual).
Recommended PartsNone
IMPORTANT NOTE: This issue is thoroughly explained in KRSII.
See document BPL10780.
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Yellow haze around red and green text
Description
Red and green text or thin lines may appear with a yellowhaze (a.k.a. yellow
halo) around the edges. This is a NO FIX issue. Some level of haloing mayalways exist.
Possible CausesHaloing is caused by yellow toner scatter and is more likely to manifest when anew yellow cartridge is installed and/or the other cartridges are weak or low.Yellow is the last color laid down. As a result, the area for yellow imaging is not
as sharp or focused electrically as the other colors. Haloing is increased by lowhumidity and unsupported media.
Troubleshooting and Suggestions
Check for unsupported media or low humidity
Try a color of text with less yellow
Check replacement history of the cartridges. One cartridge may be low.
Adjust the color density settings. (Reduce yellow).
Recommended Parts
None
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Gray hue shift
Description
Light, gray images may take on a color cast. Instead of a neutral tone (callout 1), the
gray image may appear slightly pink, blue, green, etc. (callout 2).
Possible Causes
The CLJ4550 & 4550 print a process gray (combination of cyan, magenta,
yellow and black). Unlike some printers, gray cannot be created using black
halftones.
Toner cartridges have lessened charging abilities over time.
The newest toner cartridge may create a hue of that color.
Troubleshooting and Suggestions
Clean the density sensor.
Increase or reduce the printer's density settings.
Change the color itself to a darker or lighter halftone to reduce hue shift.
Print a configuration page and look for any "weak" colors. Select gray scale in the driver if printing black only.
Recommended Parts
None. (Replacing the cartridges will temporarily fix the issue, however, gray hue shift
may reappear when one cartridge is later replaced).
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Color Halo or Haze around Solid Fill Areas or
Sharkskinning
DescriptionIn this example, a colored halo surrounds the 75% and 100%
boxes on the left-hand side of the configuration page. However,
this PQ issue can be seen anywhere on the page. ( This PQ
defect is usually more apparent in areas of higher toner
consentration).
Possible Causes
Low temperature and humidity.
Media with high resistivity. (The surface resisitivity of
the media changes once the first page is printed, so
duplexed pages are more susceptible).
Duplexing
Troubleshooting and Suggestions
Do not duplex the print job.
Try a media type with a lower surface resistivity.
Increase the humidity in the environment.
Recommended Parts
None
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Discharge marks or chicken scratch
DescriptionAn irregular, wave-like pattern of light lines appear in light,
neutral areas, typically on duplex print jobs. The effect is not
visible in darker sections of the image or text.
Possible Causes
The media (i.e. glossy paper) has low resistivity.
The environment's humidity and temperature are not within
the printer's specific range.
The secondary transfer roller is not seated correctly. Duplexed printing.
Troubleshooting and Suggestions
Change the paper type or print using an unopened ream.
Reseat the secondary transfer roller.
Avoid duplexing.
Increase the humidity in the printer's environment. Replace the ITB to reduce the amount of discharge marks,
although the media resisitivity and moisture content are the
main causes.
Send the print job at a slower speed (heavy or glossy
mode).
Recommended Parts
ITB (optional)
IMPORTANT NOTE: This issue is covered in a work
instruction. This defect shows up in many different ways. See
document BPL90041 for complete information.
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Black Toner Scatter
DescriptionIf you observe black color on a color page, you may observe a
scattering of toner particles around each black character.
These black characters may appear "fuzzy" around the edges
when compared to a monochrome LJ printout.
Possible Causes
Media with high surface resistivity (electricalcharacteristics).
Duplexed print jobs.
Color print jobs, not on black and white only pages.
Dry environmental conditions
If the "scattering" shows only on the bottom of
characters, the media has a high moisture content.
Troubleshooting and Suggestions
Use paper with a surface resistivity of: .0 to 15.0 X
10(10) Ohms/Sq 2.
Manually duplex print jobs verses using the automatic
duplex feature.
Recommended Parts
None
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Left to Right Faded Print (all colors)(Scan Direction)
Description
The entire image on a print out fades from left to right (as shown) or from right to left.
Possible Causes
Stiff media
A paper jam under the ITB assembly has popped the secondary transfer assembly up.
Broken ITB lifting arm cam.
Missing black cap on the plate kit.
Missing "c" bushing on one rail of the ITB drawer. The laser scanner mirror is blocked or contaminated. (It sits behind the silver grill).
Troubleshooting and Suggestions
Check media. Stiffer media can exhibit this issue.
Verify that the secondary transfer roller assembly is pushed down into place.
Reinstall the transfer roller.
Check the ITB lifting cams.
Check the black caps on the ITB lifting arms.
Check the "c" bushings on the ITB drawer (one is white, the other is black).
Clean the laser scanner grill behind the imaging drum
Recommended Parts
ITB cam assembly
Plate kit
ITB drawer
Laser/scanner(optional)
IMPORTANT NOTE: This issue is covered in a work instruction. See document
BPL900180.
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Fading Black Plane
Description
The black plane fades on print jobs. In this example, the black
is fading from left to right. This PQ defect generally occurs onolder printers with a fairly high page count.
Possible Causes
Issues with the black toner cartridge
Spring is bent over in the toner cartridge slot in the
carousel.
Media. (Stiffer paper can exhibit this problem). Mature printers with a fairly high page count.
The connections for CL2 and CL3 have been switched
on the Paper Feed PCB.
Defective carousel drive assembly. (The retractable HV
pin on this assembly has been found to wear, giving a
poor connection to the carousel).Troubleshooting and Suggestions
Replace the black toner cartridge
Try 80gm2
(20 lb) paper.
Recommended Parts
Black toner cartridge
Carousel drive assembly (optional) Carousel assembly (optional)
IMPORTANT NOTE: This issue is covered in a work
instruction. See document BPL90180.
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Light Print on One Side
Description
Light print in all colors show on one side of a print job.
Possible Causes
The black cap on the ITB lifting cam lever is
missing.
The ITB lifting cam lever is damaged.
One of the "c" bushings on the middle front drawer is
missing.
Troubleshooting and Suggestions
Replace the black cap
Recommended Parts
Plate Cover (if the cap is missing)
Plate Kit (if the lever is damaged) Middle front drawer(optional)
Light Print
on Left hand side of page
caused by missing black plasticcap on ITB lifting cam lever.
Replace black cap if ITB lift
cam lever(s) damaged.
Bl k C l Pl O l
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Black Color Plane Only
Description
Black is the only color put down on a color print job like on this
configuration page.
Possible Causes
Grayscale is selected in the driver (This would not apply
to an internal print job like a configuration page).
CL2 is not functioning
Troubleshooting and Suggestions Check the grayscale setting in the driver.
Verify that CL2 is seated correctly.
Verify black only on an internal print job.
Check the first three calibration value sets on the
configuration page (See callout 1).
Recommended Parts
CL2
Paper Feed PCB
High Voltage Power Supply (optional)
IMPORTANT NOTE: This issue is covered in a work
instruction. See document BPL90039.
R d C l Pl ( ) Mi i
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Random Color Plane(s) Missing
Description
Certain color plane(s) may intermittently disappear from print jobs. The first example shows a
CLJ4500 demo page missing the Magenta and Cyan color planes, while the second demo page
is missing the Magenta and Black color planes.
Possible Causes
The High Voltage contact on the Carousel assembly is broken/defective.
Troubleshooting and Suggestions
Verify that the color planes are missing from internal print jobs like a demo or engine test page.
Recommended Parts
High Voltage Power Supply (HVPS)
PS10
Carousel drive assembly (optional)
Carousel assembly (optional)
Missing Black Plane
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Missing Black Plane
Description
The black color plane is completely missing on a print job.
Possible Causes
The black toner cartridge is empty.
The sealing tape has not been removed from the
cartridge.
The connections for CL2 and CL3 have been switched
on the Paper Feed PCB.
The Carousel Assembly is defective.
Troubleshooting and Suggestions
Check the black toner cartridge for sealing tape.
Replace the black toner cartridge.
Check the CL2 & CL3 connections if the defect
appears after a service call.
Recommended Parts
Black toner cartridge
PS10
Carousel assembly
Cyan and Yellow Color Planes Missing
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Cyan and Yellow Color Planes Missing
Description
All printouts are missing the cyan and yellow color planes.
Possible Causes
A paper jam in the fusing area bent the thermister, causing the
fuser to overheat without an error reporting on the control
panel. The overheated fuser damaged the cyan and yellow
cartridges because they sit over the fuser in-between print jobs,
causing permanent damage.
This issue may also arise if the printer is unplugged before the
fans shut off.
Troubleshooting and Suggestions
Check the following parts to see if they are partially melted:
Rear door Feeder assembly
Rowel swing assembly
Carousel flap
All 4 toner cartridges
Fuser
Recommended Parts
Fuser
Black vertical streaks
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Black, vertical streaks(Process Direction)
Description
Black, vertical streaks are printed from the top edge of a
vertical page to the bottom edge.
Possible Causes
The cleaning blade on the drum may have been
gouged or scratched the drum surface.
An excessive buildup of toner on the drum.
Troubleshooting and Suggestions
Perform a half-self test to determine the origin of the
defect.
Check the imaging drum for a corresponding defect.
Recommended Parts
Imaging Drum
Black or Gray Vertical Lines
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Black or Gray Vertical Lines(Process Direction)
Description
A dark line or lines run down the printed page in the
process direction. These lines may be gray or darker
versions of the local colors in the printed images, and the
bands may be varying width on either side of the page.
Possible Causes
An excessive buildup of waste toner in one area of the
imaging drum.
Defect n the transfer roller or ITB.
Troubleshooting and suggestions
Print a half-self test to locate the source of the issue.
Remove and inspect the drum, transfer belt, and the
transfer roller for similar bands. Gently rock the imaging drum back and forth to
distribute the waste toner.
Recommended parts
Imaging drum
ITB Transfer roller
One thin vertical line
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One thin vertical line(Process Direction)
Description
A light vertical line shows up on a vertical page. The line
fades out in the darker areas and may be hairline thin or as
wide as .625 centimeters (.0625 inches) long
Possible Causes
An obstruction such as a piece of lint may be protruding out
of the laser scanner window toward the front of the printer
obstructing the laser beam.
Troubleshooting and suggestions
Clean the laser scanner windows with the printer's blue
cleaning brush. Do not use canned air.
Recommended Parts
Laser/Scanner Assembly
IMPORTANT NOTE: This PQ defect is covered in a work
instruction. See document BPL90112.
Fuser Inlet Guide Streaks
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Fuser Inlet Guide Streaks(Process Direction)
Description
One or more vertical lines may show on print jobs. (See
callout 1).
Possible Causes
Toner build-up on the fuser inlet guides
Duplexing print jobs
Troubleshooting and Suggestions Remove the fuser and inspect the fuser inlet guides.
(This may be difficult since the buildup may be the
same color as the guide).
Check for heavy duplex use.
Check for 3rd party cartridges (See document
BPL10795).
Recommended Parts
Fuser
White, vertical lines
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,(Process Direction)
Gouged ITB
Description
Vertical white lines run the entire length of a vertical page. The
lines appear even in width with possible rough edges.
Possible Causes
Damaged or obstructed ITB
Troubleshooting and suggestions
Print a configuration page to verify the PQ defect
Check the ITB, transfer roller, and imaging drum. Remove any
obstructions.
Recommended Parts
ITB
Several, thin vertical lines
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,(Process Direction)
Description
Very fine, vertical lines less than a millimeter apart may
appear in various places on a vertical page. Ghost images
may appear to the left of the text and graphics. A fine, rope-
like pattern may appear to the right of colored graphics.
Possible Causes
Defective Formatter
Troubleshooting and suggestions
Perform a half-self test
Print a configuration page if the defect appears on the
half-self test
Reseat the formatter if the defect appears on the engine
test
Recommended Parts
Formatter PCA
IMPORTANT NOTE: This PQ defect is covered in a
work instruction. See document BPL90112
Fine vertical lines
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
(Process Direction)
Description
Light vertical lines an eighth of an inch apart cover the
printed images on a page. In some cases, patterns of dark
vertical lines cover the entire page.
Possible Causes
Incorrectly seated or defective formatter
Troubleshooting and suggestions Try a half-self test
Remove the formatter and any 3rd
party memory.
Reseat the formatter
Recommended Parts
Formatter PCA
IMPORTANT NOTE:
This PQ defect is covered in a work instruction. See
document BPL90014.
DC Controller Bands
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
(Process Direction)
Description
The vertical page is broken into alternating 1/2 inch vertical sections. In the top and bottom thirds
of the page, the sections alternate displaced slices of the image; in the middle third of the page,
every other section is lighter than the original image.
Possible Cause
Defective DC Controller
Troubleshooting and Suggestions Reseat the firmware, memory, and formatter.
Remove third-party memory DIMM or EIO devices.
Dispatch technician to replace DC Controller if the issue cannot be resolved by performing
the preceding steps.
Recommended Parts
DC Controller
IMPORTANT NOTE: This PQ defect is covered in a work instruction. See document
BPL90112.
Horizontal Banding
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
(Scan Direction)
Description
Horizontal banding shows through all colors. The bands
appear in an even pattern through the entire printable area.
Possible Causes
Defective High Voltage Power Supply
Troubleshooting
Print a configuration or demo page and verify that the bandingappears in all colors.
Recommended Parts
HVPS
IMPORTANT NOTE: This issue is covered in a work
instruction. See BPL90044.
Magenta & Cyan Banding
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
Description
A horizontal magenta line followed by a cyan line prints out
on a vertical page at 152mm (6 inches) intervals, the distance
of the imaging drum.
Possible Causes
New drums can show this defect due to the charge roller
and/or the cleaning blade rubbing on the drum during
shipping. This defect is caused by a temporary positive chargethat gets trapped on the OPC surface.
Troubleshooting and Suggestions
Wait one to two days while running several copies. The defect
should clear up on its own. If it doesn't, replace the imaging
drum.
Recommended Parts
Imaging drum (optional)
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Gray, Horizontal Bands(Scan Direction)
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
(Scan Direction)
Description
Gray, horizontal bands appear on all printouts.
Possible Causes
Defective Formatter PCA.
Troubleshooting and Suggestions
Verify that internal printouts like an engine test andconfiguration page show the horizontal bands.
Recommended Parts
Formatter PCA
IMPORTANT NOTE: This issue is covered in a work
instruction. See BPL90044.
Complete Discoloration from Edge to Edge
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
Description
The entire page is discolored and streaked from edge to edge
with multiple colors.
Possible Causes
Defective High Voltage Power Supply
Troubleshooting and Suggestions
Verify that the defect shows up on an internal print job like aconfiguration page.
Recommended Parts
High Voltage Power Supply (HVPS)
Color Plane Offset
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
Description
Colorplaneoffset will manifest itself when one colorplane
shifts up or down. In this example, the yellow colorplanehas shifted up higher than the other color planes.
Possible Causes
In many cases, the drum drive assembly is defective and
needs to be replaced.
Troubleshooting and Suggestions
Verify that the defect shows on a configuration page.
A service technician can perform additional diagnostic tests
like registration adjustments to isolate the cause.
Recommended Parts
Drum drive assembly DC controller
IMPORTANT NOTE: This PQ defect is covered in a work
instruction. See document BPL90011.
Solid Black Pages
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
Description
All print jobs print as a solid black page without margins. This
defect also appears as a heavy grayish print out.
Possible Causes
The HVPS is normally attributed to this problem. If the
primary charge roller in the imaging drum does not charge the
drum to 600v, the charge levels could be close to zero. If this
occurs, toner will be attracted to these areas, causing a heavyblack or gray background.
Troubleshooting and Suggestions
Verify that the print out does not have a margin.
Check and clean the HVPS contacts that supply the
primary charge bias to the imaging drum (See Figure 3
in BPL90009 for the location).
Recommended Parts
Imaging drum
HVPS
DC Controller PCB
IMPORTANT NOTE: This issue is covered in a work
instruction. See document BPL90009.
Solid Black Page with Margins
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
Description
All print jobs print as a solid black page with margins.
Possible Causes
This defect shows the normal margin expected if an image
was printed, meaning the laser beam was switched on at all
times.
Troubleshooting and SuggestionsVerify that the solid black page has a margin
Recommended Parts
Laser/scanner assembly
DC Controller PCB
IMPORTANT NOTE: This issue is covered in a workinstruction. See document BPL90009.
Darker than normal print
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
Description
Images, including printer test pages, print much darker than
normal.
Possible Causes
This is normally caused by the printer failing to go through
calibration. The configuration page displays four separate
blocks of numbers that indicate the calibration density
settings for each color. If these settings are all zeros, the
printer has not gone through calibration correctly. In some
cases, the density sensor (PS14) is covered by toner dust or
is defective.
Troubleshooting and Suggestions
Powercycle the printer and verify that the printer
calibrates.
Print a configuration page and check the calibrationvalues (See Figure 1 in BPL90143 for the location of the
calibration values).
Clean the density sensor.
Verify that the media is within specification
Remove any third-party memory.
Recommended Parts
Density Sensor (PS14)
IMPORTANT NOTE: This PQ defect is covered in a work
instruction. See document BPL90143.
Light/Mottled Print
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
Description
Greens, blues, and purples -- colors that include CYM -- may have
thick horizontal bands of light running through them. A cyan
smudge appears at the top of the vertical page.
Possible Causes
Toner ages with carousel rotation and may become "old" before it
is used. Also, 3rd party cartridges can cause this issue (See
BPL10795).
Troubleshooting and Suggestions Check the age of the toner cartridges (in pages, if possible).
Observe the secondary colors on the configuration page for
mottling.
Use the following technique to determine which primary color
makes up the secondary color to identify which toner cartridge is
causing light or mottled print. To determine the low cartridge, lookfor the common colors showing the defect. For example, if green
and blue share the defect, then the common color is cyan.
1. Red = Magenta + Yellow
2. Green = Cyan + Yellow
3. Blue = Cyan + Magenta
Recommended Parts
Toner Cartridge
IMPORTANT NOTE: This issue is covered in KRSII. See
BPL08701 for complete details.
Light Bands of Color on OHTs (4550 only)
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
Description
When using overhead transparencies (OHT), areas of the page
that are supposed to be solid color, print with bands of lighter
color mixed within. This issue is most often seen with blueand green colors and in MS PowerPoint files because they
often have a dark blue background. In this example, the
circled blue box should be solid dark blue. However, light
bands run through it. Banding is also seen in other areas of
this example, including the green background.
Possible Causes
The CLJ4550 uses different color tables for paper media than
for OHTs. This issue is caused by a problem with the OHT
color table.
Troubleshooting and Suggestions
Print the same file on paper media to see if the bandingreoccurs. If not, the problem is with the OHT color
table.
Upgrade to the latest firmware. (This issue was fixed
with firmware version 1.011.0 for the 4550).
Try using a different shade of color. If possible, do not
use blues and greens.
Recommended Parts
Firmware version 1.011.0 or newer
IMPORTANT NOTE: This issue is discussed in a service
note. See service note C7085-02.
Bubble Print
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
Description
Bubble print can be described as overlapping circles randomly
spread throughout any print job.
Possible Causes
This defect usually occurs after service has been done on the
printer and is caused by arching at the connection to the imaging
drum. Possible causes may include the following:
Obstructed or defective drum ground connector
Defective imaging drum
Troubleshooting and Suggestions
Verify if the printer has been serviced. If so, try to determine
what parts were removed and/or replaced. Also, check the
HVPS contact on the drum.
Recommended Parts Drum ground connector
Imaging drum (optional)
Light random lines or missing toner
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HP Confidential CLJ4500 & 4550 Print Quality Defects GuideCurtis Gold & Deborah Hahn November 2001
Description
Irregular light streaks or missing toner (scratch marks)
appear on images. Toner is raised (not smooth) across the
page and may not adhere well.
Possible Causes
Fuser roller delamination can be caused by the fuser
overheating, unsupported media melting to the fuser roller,
or fuser jams.
Troubleshooting and suggestions
Verify that the media is within specifications.
Examine the fuser rollers. Instead of a smooth brown
surface, the rollers will likely show creases or missing
bits of the outer layer.
Recommended PartsFuser
Water Spots (Sand Dunes)
Description
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Description
Spots that look like water drops appear on a printout. These spots
appear more readily on the first (front) page of a duplexed page
and range from 1 to 7mm in diameter.
Possible Causes
Most likely, the cause rests with post transfer breakdown. The
issue is usually media related and is magnified on duplex print
jobs.
Troubleshooting and Suggestions
Check media specifications.
Try a fresh ream of paper.
Turn the duplex option off from the control panel.
Do not duplex.
Ensure that the resistor holder and transfer assembly are
making good contact.
Recommended Parts
Transfer Assembly
Colors switched or wrong
Description
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Description
The image prints with correct sharpness but with the
wrong colors. Depending on the color scheme of the
original image, the print may also appear too dark.
Possible Causes
This case was resolved by switching two of the toner
cartridges that had been installed in each other's slots in
the carousel. The cartridges had been forced into the
printer hard enough to break the locator keys off the
cartridge shutters.
Troubleshooting and Suggestions
Print a configuration page and check the bottom of
the page for a mismatch between two of the colors
and their color names.
Switch the cartridges to the correct positions.
Recommended Parts
None