copying or printing in black now has green tinge

[bob1600]

printing in black now has green tinge using as copier and printing business cards

[senan6806]

@bob1600

A warm welcome to HP Support Community! I'd like to help.

Does it happen when you copy or print on an A4 or Letter paper?

What's the printer model?

Let me know!

[bob1600]

Model office jet pro 6978, copying/printing on letter size paper

green print happens when making b&w copies under glass, feeder copying results in light grey copy.

tried to print business cards as before, those came out green 

print quality diagnostic page prints correctly as well as other printer maintenance pages

this started after replacing all ink cartridges, only use hp cartridges

[senan6806]

@ bob1600

Thanks! Power resetting the printer and then performing an automated/manual cleaning may resolve the issue. Let's try these steps:

Please ensure the printer is up-to-date with its firmware. If you are unsure, you can download and install the latest firmware update from here.

1) Make sure this printer is plugged into a direct wall, not a surge protector

2) Remove all of your ink cartridges from the printer and close the door

3) Remove the power cord from the back of the printer (Do no press the power button)

4) Clean the ink cartridges, refer to step 3 from this document.

5) Plug the power cord back into the printer

6) Wait for the printer to turn on completely, then install the ink cartridges.

7) From the printer control panel, open the Setup  menu.

😎 Open the Printer Maintenance or Tools menu.

9) Touch Clean Page Smears or Clean Smear.

10) From the printer control panel, open the Setup  menu.

11) Open the Printer Maintenance menu.

12) Open the Tools menu, and then touch Clean Printhead.

Let me know how it goes!

If the information I've provided was helpful, give us some reinforcement by clicking the Accepted Solution and Kudos buttons, that'll help us and others see that we've got the answers!
Have a great day!

[bob1600]

Thanks for the help, once I cleaned ink cartridges (had to do it twice) the printer now copies black properly.

Test page was missing magenta colored rectangle when doing original test. Original problem occurred after installing new color cartridges.  So my next question is why does the copy function rely on other colors when only wanting black copy?

[senan6806]

@bob1600

I believe some amount of color inks are used to create Rich black. The printer uses a mixture of solid black over one or more of the other CMY colors, resulting in a darker tone.