HP M255dw Black is LIght Gray, Color

[Erne4]

Hp M255dw worked great for 4 years,

No system changes when problem started.

Problem;

Black text is very light gray(uniform density), colors print normal

Comparison prints are make from the supply report from printer touch screen, I don't feel its a driver issue

always used Hp toner

Attempted resolution;

1. Re calibrated & restored to factory defaults

2. Ran cleaning page form Menu

3. replaced Black toner cartridge 206A

4. Upgraded firmware to datecode 20231206

5. Re calibrated

6. swapped back to original 206X cartridge

7. Re-calibrated

8. cleaning page

9. power on reset multiple times

No change in print quality for any of resolution steps

Does anyone have any ideas?

Anyone know how to enter the service mode?

Thank you

Erne4

[A_Gayathri]

Hi @Erne4,

Welcome to The HP Support Community.  

Thank you for posting your query, I will be glad to help you.

I understand your detailed steps in troubleshooting your HP Color LaserJet Pro M255dw, it appears you have covered most of the common fixes. Since black text remains light gray despite the toner cartridge replacement and multiple calibrations, it indicates a deeper issue, likely related to the printer's hardware. 

Here are a few additional steps and considerations:
 

Additional Troubleshooting Steps

Check the Imaging Drum:

• The imaging drum might be causing the problem. Even if the colors print fine, the black drum section could be worn out or damaged. Inspect the drum for any visible damage or wear.

Clean the Laser Scanner Assembly:

• Dust or debris on the laser scanner mirrors can affect the printing quality. You might need to open the printer and clean the laser/scanner assembly. This should be done carefully to avoid further damage.

Check for Firmware/Software Glitches: Update the firmware on an HP printer

• Although you have updated the firmware, try reinstalling it or rolling back to a previous version to rule out any bugs introduced in the latest update.

Accessing Service Mode

Accessing the service mode on HP printers typically involves a sequence of key presses. Here’s a general method, but please note that specifics can vary by model:

Turn Off the Printer:

• Make sure the printer is completely powered off.

Press and Hold Specific Buttons:

• Simultaneously press and hold the buttons for 2-6 (for some models) on the numeric keypad or the Home and Back buttons.

Turn On the Printer:

• While holding these buttons, turn the printer back on.

Enter Service Mode:

• Continue holding the buttons until the display changes, indicating that you are in the service menu.

Refer to this document:  HP Color LaserJet Pro M255dw User manual

I hope this helps. 

Take care and have a good day.

Please click “Accepted Solution” if you feel my post solved your issue, it will help others find the solution. 

[Erne4]

Hi Gaya1239,

Thank you for the quick response.

Suggestion 1. Check the Imaging Drum

The M255dw has the photo conductor drum for each color interrogated into the toner cartridge.  Swapping the toner cartridge should rule out this as a potential cause.  The image is transferred from the photo conductor to an accumulating belt and then transferred to the paper just before entering the fuser.  I don't know if it makes 1 pass by all the photo conductors or 4.  I have not fully inspected the accumulating belt yet.

Suggestion 2. Clean the Laser Scanner Assembly

The laser scanner assembly appears to be a seal module and the scan mirror is not easily accessible It has 4 exit slots where the laser is directed to each of the 4 photo conductors.  So I used canned air to blow off the stationary mirror for all 4 colors.  I was afraid accessing the inside of the module would mess up the alignments inside.  This did not change the darkness of the black text.

Suggestion 3. Check for Firmware/Software Glitches

I have not attempted to downgrade yet.  Problem existed with original code level and with the upgraded version.  when i upgraded it was the first time this printer has been connected to the internet.  but it worth a try.  Tomorrows task.

as for the service mode.

the M255dw only has a power button and a touch screen no other physical buttons.  I tried the power button and the home and back buttons on the touch screen with no results.

I also examined the main board and nothing in the high voltage section that showed signs of fried components or scorching.  I did a cursory look at the contact at the end of the photo conductor rolls and the black one looks like the cyan.  I also re-seated the connectors on the laser scan unit.  The alignment of the toner cartridges to the accumulating belt is very sloppy i will look into that issue as well.

your response has been very helpful.

Thanks again

[A_Gayathri]

HI @Erne4,

Thank you for your response. If you need further assistance feel free to reach out to us. 

If the information I've provided was helpful, give us some reinforcement by clicking the Accept as Solution, and on the public post, that'll help us and others see that we've got the answers!

Have a great day ahead!