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