When I print no blck color shows even with a new

Replace the black cartridge. Even new ones can sometimes be bad.

please replace balck cartridge with other or pump it with air from its in inserting hole.or clear ink head connector

this should take care of it,,....

http://cob.fsu.edu/tech/printermanuals/laserprinters/HPLJ2600n.pdf

rememmber its your choice to vote, it counts

regards

printer is probably too old . buy a new one

or just print everything out in blue or sumtin other than black.

(thats what i do when my black ink is out)

Many printers will not print if one color is out, some will. One thing to check is to make sure that when you print, the option for "balck and white" is selected in the printing preferences.

Many people don't realize that even though the document may be black and white the printer still processes it as a color document which wastes costly supplies.

Have you replaced with original HP cartridges? HP mark is well known for sensitivity to non-original cartridges.

u check ur head is working properly i think this main error of head where u insert balck vartrige if u have same printer then u have check replace the black cartrige find out it work properly then sure ur balck head is damage

yes u can use it with black and white 

hp3420 printer driver

Check it's not a software driver fault, uninstall both printers drivers from pc and disconnect the printers and restart. Re-install the driver and then connect the printer when prompted