HP 4700n Service Manual - Page 468

Table 7-21 Causes for vertical lines of white dots Cause The charge roller in the cartridge is damaged or contaminated. The transfer charging roller is worn or damaged. Solution Replace the affected cartridge. If dots occur in all colors, replace the ETB. Calibrate the printer after replacing the ETB. See Full Calibrate Now on page 539. Dirt on the front or back of the paper This table contains information about the causes of and solutions for dirt on the front or back of the paper. Table 7-22 Causes for dirt on the front or back of the paper Cause Solution One or more of the rollers are dirty. See Repetitive defects troubleshooting on page 454 for information about identifying the roller that might be dirty. Clean the indicated roller. If the roller is still dirty after cleaning, replace the appropriate roller, cartridge, or assembly. The pickup roller is dirty. Clean the roller. If the roller is still dirty after cleaning, replace the pickup roller assembly. A poor contact exists in the attaching bias contacts between Clean the contacts. Replace them if they are still dirty or are the ETB and the high-voltage PCB. damaged. The high-voltage PCB is defective or one of the connections is loose. 1. Check the connections. 2. Replace the high-voltage PCB. See High-voltage power supply PCB on page 324. The DC controller may require a firmware upgrade or the connector to the high-voltage PCB (J1006) is disconnected or not seated properly. 1. Upgrade formatter and DC Controller firmware, which can be found in a single .rfu file from http://www.hp.com/ support/clj4700 or http://www.hp.com/support/cp4005. 2. Check the connector (J1006) on the DC controller PCB to make sure it is seated correctly. Vertical lines This table contains information about the causes of and solutions for vertical lines. 448 Chapter 7 Troubleshooting ENWW