HP OfficeJet Pro K850dn User Manual

5.Lift the handle of a printhead and use it to pull the printhead out of its slot.
ENWWMaintaining the printheads 63
 

6.Carefully remove any ink from the contact pads on the printhead using a dry cotton swab or a
soft, dry, lint-free cloth that will not come apart or leave fibers behind.
CAUTIONOnly wipe the contact pads. Wiping the nozzles (located on the underside of
the printhead) can cause severe damage to the printhead.
7.If some residue remains, slightly moisten the swab with distilled, filtered, or bottled water, and
continue wiping until the contacts are clean.
CAUTIONAvoid using drinking water or alcohol, which...

13
.Close the top cover.
14
.Where necessary, repeat the above steps for the remaining printheads.
15
.If you installed a new printhead, wait while the printer initializes it and prints an alignment page. If
you removed and reinserted printheads but did not install a new printhead, print an alignment
page manually. See 
To align the printheads.
If the alignment page does not print, make sure the printhead latch and all covers are securely
closed.
ENWWMaintaining the printheads 65
 

Replacing the printheads
NOTETo find out which printheads are compatible with your printer, see HP supplies and
accessories.
NOTEOnly replace printheads after you have attempted to clean the printheads. See To
clean printheads automatically and To clean the printhead contacts manually.
1.Open the top cover.
2.Lift to open the printhead latch.
66 Chapter 5   Maintaining and troubleshooting ENWW
 

3.Lift the handle of a printhead and use it to pull the printhead out of its slot.
ENWWReplacing the printheads 67
 

4.Remove the new printhead from its package, and then remove the protective tape.
68 Chapter 5   Maintaining and troubleshooting ENWW
 

5.Insert the printhead into its color-coded slot. Press down firmly on the printhead to ensure proper
contact.
ENWWReplacing the printheads 69
 

6.Pull the printhead latch all the way forward, and then press down to ensure that the latch is
properly engaged. You might have to apply some pressure to engage the latch.
7.Close the top cover, and then wait while the printer initializes the printheads and prints the
alignment pages.
70 Chapter 5   Maintaining and troubleshooting ENWW
 

Diagnosing the print quality
To verify the print quality of the printer, you can perform print quality diagnostics, which involves
printing of test patterns. This will help you decide whether to run any maintenance tools to improve
the print quality of your printouts.
Printer driver
●In Windows 2000 or XP, click the Services tab, click Service this device, and then follow the
onscreen instructions.
●In Windows 98, click the Services tab, click PQ (print quality) diagnostic page, and then follow
the...

Testing the paper feed
If you encounter frequent jams, perform a paper feed test to ensure that the paper path of the tray or
duplex unit is clear. The process will feed 20 blank pages.
●Printer driver
Click the Services tab, click Service this device, and then follow the onscreen instructions.
●Toolbox (Windows)
Click the Printer Services tab, click Test Paper Feed, and then follow the onscreen instructions.
●HP Printer Utility (Mac OS)
Open Information And Support, click Test Paper Feed, and then...