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Visual chart of HP LaserJet print defects

Visual chart of HP LaserJet print defects

This is a useful reference chart of images, showing a picture of each of the most common print defects found in laser printers. Use this guide to identify your print defect, and read more about the print defect with potential causes and solutions.

Below is a chart of common print defects found in laser printers. It is not a complete list but should cover 90% or more of the most common image defects. Click on the defect for more info on potential causes and solutions:






Background scatter

Possible Cause -Solution

  • Toner cartridge is defective - Install a new toner cartridge

  • Fuser assembly is bad - Do a half-way test to determine if it is the fuser

  • Transfer Roller is dirty or worn. A worn Transfer Roller can cause background scatter due to improper bias voltages. - Replace the transfer roller.






Black lines - parallel or perpendicular

Possible Cause -Solution

  • parallel or perpendicular If the lines are repeated at a consistent interval down the page, this is a repetitive defect.--See the Repetitive Image Defect Ruler in the service manual to measure and determine source of lines.






Black page

Possible Cause -Solution

  • Defective toner cartridge --Install a new toner cartridgeblack pages

  • High voltage power supply circuit is defective (not supplying the correct negative voltage)--Replace the High Voltage Power Supply PCA

  • DC controller PCA is defective. If the DC Controller turns on the laser beam continuously, the entire surface of the Photosensitive drum is neutralized causing a completely black page.--Replace the DC Controller PCA






Blank page

Possible Cause -Solution

Occasional Pages

  • Multiple feeds--The printer may be feeding two or more pages at once because the paper is difficult to separate. Flex the paper a bit to help separate before installing in printer.

  • Software configuration ,. network configuration--Re-install printer driver.  Check paper size settings in software. Check any software/network settings related to printing a blank separator page between jobs.

  • Malfunctioning paper pickup assembly--The paper pickup solenoids can misfire and intermittently cause the pickup rollers to rotate an extra revolution.  This will cause a blank page.  Replace or repair paper pickup solenoids.

All Pages

  • No toner is available  for print--Remove sealing tape on toner cartridge, or replace the toner cartridge if necessary.

  • Malfunctioning laser shutter--Perform a half-way test  and see if there is an image on the imaging drum. If there is no image on the drum, check the laser shutter for correct operation when inserting the toner cartridge

  • No transfer roller voltage--Perform a half-way test  and see if there is an image on the imaging drum. If there is an image on the drum, make sure the transfer roller is installed. Without transfer roller voltage, toner cannot be attracted from the surface of the drum to the print media. Replace the transfer roller if necessary.

  • No developing bias--Perform a half-way test  and see if there is an image on the imaging drum. If there is no image on the drum, clean the high-voltage power supply contacts. With no developing bias charge, toner is not attracted to the drum. Replace the engine controller board if necessary.

  • Defective laser scanner cable--Perform a half-way test  and see if there is an image on the imaging drum. If there is no image on the drum, low-level signals exchanged between the laser/scanner assembly and the engine controller board could theoretically affect laser output. Replace the laser/scanner cable assembly if necessary.






Blank spots

Possible Cause -Solution

  • Defective toner cartridge--Replace the toner cartridge.

  • Dirty laser scanner mirrors--Clean the laser scanner mirrors. On some models, this is an advanced procedure; consult the service manual for instructions on accessing the laser scanner assembly.

  • Contaminated or deformed transfer roller--Replace the transfer roller.






Bubble print

Possible Cause -Solution

  • Defective toner cartridge--Replace the toner cartridge.

  • Defective High Voltage Power Supply--Replace the High Voltage Power Supply

  • Photosensitive drum inside toner cartridge is not grounded--Check for proper mounting of the High Voltage Power Supply, and the HVPS ground contact on the toner cartridge. Check for proper seating of toner cartridge. Replace toner cartridge.

  • Paper does not meet specifications -- moisture content, conductivity, or surface finish may not work correctly with the electrophotographic process.--Try a different paper type






Compressed print

Possible Cause -Solution

  • Drive gear is broken or worn--Inspect and replace the worn gear of assembly

  • Toner cartridge bushings are too tight--Replace the toner cartridge







Contamination on back

Possible Cause -Solution

  • Contamination inside printer--1. Print at least 10 pages to see if the problem goes away on its own.  2. Print a cleaning page (consult User's Guide/ Service Manual.) 3. Identify and clean the contaminated part, or better yet, replace the contaminated part if replacements are orderable. 4. If contamination continues, check toner cartridge for leaks. Replace cartridge.

  • Print media does not meet printer specifications, or is stored improperly. 1. Print a few more pages to see if the problem corrects itself. 2. Turn over the stack of media in the tray. Also try rotating the media 180 degrees. 3.  If the print media does not meet HP specifications, replace the paper, and advise the customer to use the recommended print media and store it properly.






Creases

Possible Cause -Solution

  • Paper is loaded incorrectly.--Make sure print media is loaded into tray correctly, and that the tray guides are adjusted properly to fit against the paper stack.

  • Determine the cause by performing a half-way test to isolate the defective component.--Replace defective component. Common possibilities include slipping paper pickup assembly, slipping feed assembly, slipping fuser assembly.






Curl

  • Print media does not meet printer specifications or is stored improperly.--1. Print a few more pages to see if the problem corrects itself. 2. Turn over the stack of media in the tray. Also try rotating the media 180 degrees. 3. I the print media does not meet HP specs, replace the paper.

  • Wrong fuser setting for print media type--From the paper-handling menu on the control panel, change the fuser mode setting or choose another paper type from the printer driver.

  • Wrong output bin--Print to a different output bin (top or rear output bin).






Distorted image

Possible Cause -Solution

  • Defective engine controller board--Replace the engine controller board

  • Defective laser scanner--Replace the laser scanner

  • Poor connection of cables to the engine controller board--Reseat the cables connected to the engine controller board

  • Print media does not meet printer specifications or is stored improperly--1. Print a few more pages to see if the problem corrects itself. 2. Turn over the stack of media in the tray. Also try rotating the media 180°. 3. If the print media does not meet HP specifications, replace the paper, and advise the customer to use the recommended print media and store it properly






Dropouts

Possible Cause -Solution

  • Failing toner cartridge, or wrong toner density setting--Replace toner cartridge, or wrong toner density setting

  • Failing upper fuser roller in fuser--Replace fuser

  • DC Controller is defective (low primary voltage)--Replace the DC controller

  • High Voltage Power Supply is defective--Replace the high voltage power supply

  • Transfer roller is defective--Replace the Transfer Roller






Faded print w. bubbles

Possible Cause -Solution

  • Toner cartridge drum not grounded properly--With no ground path, the drum cannot discharge. The negative charge on the drum repels toner and leaves a white page with bubble print. 1. Replace toner cartridge. 2. Check the drum ground spring and reconnect it, if necessary. 2. Replace the engine controller board






Fading print

Possible Cause -Solution

  • Toner supply is low , failing--Shake the cartridge gently to redistribute the toner, or replace the cartridge

  • Transfer roller is defective or incorrectly installed.  If the Transfer roller loses conductivity, it cannot effectively pull toner from the drum to the paper--Inspect the Transfer Roller for proper installation and contact. If the Transfer Roller is damaged, replace it

  • Laser mirror is dirty or shutter is not functioning--Clean the scanner mirror.  Check the Laser/Scanner shutter door for proper operation. If defective, replace the Laser/Scanner Assembly.

  • Print density is set incorrectly--Change to a darker setting and retry printing

  • EconoMode is on. (EconoMode saves toner by reducing the dot density. This may appear to be a print quality problem in some cases.)--Turn EconoMode off. EconoMode settings are stored in either the printer driver or the job application.






Faulty Registration

Possible Cause -Solution

  • Paper guide on the paper tray is incorrectly adjusted.--If the guide is pushing too tightly against the paper, it may be delayed in being pulled into the printer. If the guide is too loose, it may cause image skewing. Make sure that the paper guide is adjusted for the correct paper size and is locked into position.

  • Paper is being picked up skewed; worn pickup , feed, or registration rollers.-- Inspect all paper path rollers, looking for wear, cracks, or glazing. Replace worn rollers.

  • Paper tray is overloaded. If the tray is overloaded, the Pickup Rollers may not pick correctly.--Reload proper amount of paper squarely in the tray. Review paper loading with the customer.






Gray background

Possible Cause -Solution

  • Faulty toner cartridge--Replace the toner cartridge

  • High voltage power supply failure--Replace high voltage power supply

  • Formatter failure--Replace formatter

  • Wrong toner density setting--From the print-quality menu on the control panel, adjust the toner density setting.






Horizontal black lines

Possible Cause -Solution

  • Defective laser scanner assembly or engine controller board--1. See the “Repetitive defect ruler” 2. Reseat connectors on the laser scanner and engine controller board. 3. Replace the laser/scanner assembly followed by the engine controller board, if necessary






Horizontal smudges

Possible Cause -Solution

  • Paper path contamination or damage--1. See the Repetitive defect ruler. 2. Check the toner cartridge and replace it if necessary. 3. Check the fuser and replace it, if necessary






Horizontal white lines

Possible Cause -Solution

  • Defective toner cartridge--Replace the toner cartridge

  • Dirty / defective laser scanner assembly--Clean laser scanner mirrors. Replace scanner assembly if necessary.

  • Defective DC controller--Replace DC controller