The toner cartridge is a consumable, user-replaceable component that contains the printing mechanism (photosensitive drum, primary charging roller, developing station, and cleaning station) and a supply of toner. The lifespan of a new toner cartridge is approx. 3,000 pages. The useful life of the installed toner cartridge can be extended further by using the EconoMode feature. You should replace the toner cartridge installed in your HP LaserJet 4ML Laser Printer when/if:
· The message [12 OPEN OR NO EP] appears on the display panel – The SW201 switch is open, which means that the HP LaserJet 4ML Laser Printer does not detect the toner cartridge. You should reinstall the toner cartridge, and then close the top cover. Please replace the installed toner cartridge with a new one if the problem persists.
· The message [16 TONER LOW] is displayed – The installed toner cartridge is nearly empty. You should install a new toner cartridge in order to be avoided print quality problems.
· Printouts are blank – You must make sure that the sealing tape has been removed from the new toner cartridge during the installation. Please replace the installed toner cartridge if the problem persists.
· Solid black printouts – The installed toner cartridge is defective. Please install a new toner cartridge.
· Faded printouts – This print quality problem appears when the toner level drops under the normal operational minimum. Thus, you should install a new toner cartridge in your HP LaserJet 4ML Laser Printer.
· Vertical black lines appear; Horizontal black lines; Repetitive image defects occurring at intervals of 2.95 inches; – The photosensitive drum of the installed toner cartridge is damaged. You have to install a new toner cartridge to improve print quality.
· Background toner scattering – This is an indication for a leaking toner cartridge. Please install a new toner cartridge.
· Compressed print – The components of the installed toner cartridge have been exhausted. You should install a new toner cartridge in your HP LaserJet 4ML Laser Printer.