Missing Black on printing. Gray is ok

[FrenRoc]

Black color is missing or become very very light gray color.  All the rest of the colors, included two level of Grays are ok.

All ink cartages checked ok.  Print head has been cleaned twice.  As matter of fact, print head has also been rinsed in warm water.

[Riddle_Decipher]

@FrenRoc

Thank you for joining HP Forums. 

I'll be glad to help you 🙂 

As I understand the printer doesn't print black anymore,

Don't worry as I'll be glad to help, however, to provide an accurate resolution, I need a few more details: 

Have you recently replaced the ink cartridges? or any hardware changes to the printer before the issue occurred?

HP doesn't recommend rinsing the printhead in warm water, did you consult a tech before you did the same?

While you respond to that, here's a few things you can do:

Step 1: Use genuine HP ink cartridges

HP recommends that you use genuine HP ink or toner supplies. HP cannot guarantee the quality or reliability of non-HP or refilled cartridges. If you do not use genuine HP cartridges, the steps in this document might not resolve the issue. To check the authenticity of your cartridges, go to hp.com/go/anticounterfeit.

Step 2: Allow automatic servicing to complete

Your HP printer has an automatic servicing routine that can solve many print quality issues. There is nothing you need to do. The print quality should improve a few hours after you experience the issue.

Step 3: Check the paper

Make sure the paper is appropriate for the print job. If it is not, reload the printer with an appropriate paper type.

Step 4: Check the print settings

Check the print settings to make sure they are appropriate for your print job.

CLICK HERE FOR MORE STEPS AND INSTRUCTIONS.

If you've already cleaned the printhead and the issue persists, perhaps, it time to replace it,

I recommend you Contact HP to get it done:

Please use the following link to create yourself a case number, then call and it may help speed up the call process:

Step 1. Open link: www.hp.com/contacthp/

Step 2. Enter Product number or select to auto detect

Step 3. Scroll down to "Still need help? Complete the form to select your contact options"

Step 4. Scroll down and click: HP contact options - click on Get phone number to obtain a case along with the phone number.

They will be happy to assist you immediately.

If you wish to show appreciation for my efforts, 

Mark my post as Accepted Solution.

And click on the Purple Thumbs up icon at the bottom of my comment.

Regards,

[FrenRoc]

Have you recently replaced the ink cartridges? or any hardware changes to the printer before the issue occurred?

Yes, I replaced all ink cartridges about a month ago.  I was working fine for couple weeks.   

No hardware changes to the printer before thie issue occured.

HP doesn't recommend rinsing the printhead in warm water, did you consult a tech before you did the same?

I just followed the suggestion on you-tube to perform the rinsing.  I haven't contact any tech for that.

All my ink cartridges are genuine HP.

Allow automatic servicing to complete and find nothing wrong.

I use this paper type all the time.  I believe this issue have nothing to do with paper.

That sounds like the problem is on the PrintHead!!

[Chimney_83]

Hi @FrenRoc, I am the @Chimney_83. It looks like you were interacting with @Riddle_Decipher, but he is out of the office today so I'll take over from here.

Thanks for the reply and trying the suggested steps. If you have installed new black cartridges and performed cleaning the printheads. 

Recommend you refer to Step 7 in this HP Article. Perform an alignment on the printer. 

If the issue persists, please replace the printhead on the printer. 

For any service options please contact our phone support for assistance. 

Please follow the procedure mentioned below to contact our phone support. 

• Open link:  www.hp.com/contacthp/
• Enter Product number or select to auto detects
• Scroll down to "Still need help? Complete the form to select your contact options"
• Scroll down and click on HP contact options - click on Get phone number.

Let me know how it goes. 

[FrenRoc]

May I ask a technical question?  Can you explain to me about how the printer controls the level of color?  In video, there are multiple bits, say 8 bits, 10 bits, and so on.  The higher bit represents higher intensity.  In my case, it seems like the high bit that never turns on so that instead of give me a high level, I get a very low level.  i.e. changing from 011111.... to 100000.... but my machine get 000000....

Is this make sense to you?

[Chimney_83]

Thanks for the reply, to the best of knowledge there is not provision to change the bits. You can use the print settings in the application you are using to print from to change the print quality. 

If the issue persists, please contact our phone support for the service options available. 

Please follow the procedure mentioned below to contact our phone support. 

• Open link:  www.hp.com/contacthp/
• Enter Product number or select to auto detects
• Scroll down to "Still need help? Complete the form to select your contact options"
• Scroll down and click on HP contact options - click on Get phone number.

Keep me posted. 

[FrenRoc]

Thanks!

I didn't meant to change the bit by us (the user).  I meant either the output bit on control unit was bad, or the connection that related to that bit was open up between the controller and the printhead.  If that is a case, changing the printhead will not help unless the open circuit was on the printhead.

Do you have the signal information on the printhead contact?

[Chimney_83]

Thanks for the reply, there is no way to be sure whether the issue is with the printhead or the printer unless you replace the printhead and check. 

Recommend you to contact our phone support to check on the printhead replacement options and the printer trade-in options. 

Once you speak to our phone support and discuss the options, you can take a call whether to replace the printhead or the printer. 

Let me know how it goes. 

[FrenRoc]

Ok!  I will call the phone support tomorrow. 

Thanks again

[Chimney_83]

Please do contact our phone support in your spare time to check on the service options available. 

Please do post your technical queries on our Forums for assistance. 

Keep me posted.