Replaced the DC Controller PCB but now all black is light grey

[WMK77]

I replaced the DC controller PCB. The error, that I found to indicate the need for replacing the PCB, is no longer showing, nor any other errors.

But, all prints are in light grey where they should be black. Colors are fine. The problem is with the black.

The black toner indicates that it should still be good for anothe 1500 prints...

Any idea what the cause is here?

Any help is highly appreciated! 

[VikramTheGreat · Accepted solution]

Hi @WMK77,

Welcome to the HP Support Community.
 

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

Since you’ve replaced the DC controller PCB on your HP Color LaserJet Pro MFP M277dw and the original error is resolved, but black prints are now coming out light gray, it strongly points to a post-repair calibration or hardware communication issue, particularly between the DC controller and the black toner/imaging drum.

1. Steps to Fix

• Perform a Cold Reset / NVRAM reset to force the printer to reinitialize calibration and communication:
  1. Power off the printer.
  2. Press and hold the Right Arrow (→) and Cancel (X) buttons.
  3. While holding, turn on the printer.
  4. When Permanent Storage Init appears, release the buttons.
  5. Allow the printer to fully initialize.

⚠️ This will erase custom settings (network config, etc.) — back them up if needed.

2. Black Developer Unit or Laser Scanner Assembly Issue.
✅ Fix

• Power off, remove the black toner cartridge, and inspect:
  • Any toner leakage, bent pins, or burned contact points?
  • Gently shake the toner and reinstall.
• Try swapping in a new or known-working black toner, if available.

3. Run a Color Calibration / Cleaning Page

• Go to Setup > Service > Cleaning Page and Color Calibration.
• This can realign the toner application and help if there has been controller or sensor drift.

I hope this helps.

Take care, and have an amazing day!
 

Did we resolve the issue? If yes, please consider marking this post as "Accepted Solution" and click "Yes" to give us a helpful vote - your feedback keeps us going!

Regards,

VikramTheGreat

[WMK77]

The recalibration solved the issue. Just HD to trigger this by pressing the bottom right corner on the touch screen during start up

[VikramTheGreat]

Hi @WMK77,

That's fantastic news — I’m glad to hear the recalibration resolved the issue!

Thank you as well for sharing the specific steps.
 

Pressing the bottom right corner of the touchscreen during startup to trigger the recalibration.
 

That tip can be incredibly helpful to others in the community facing similar touchscreen alignment or responsiveness issues. Your contribution is much appreciated!
 

If anything else comes up, feel free to reach out — we’re always here to help.

Take care, and have an amazing day!
 

Did we resolve the issue? If yes, please consider marking this post as "Accepted Solution" and click "Yes" to give us a helpful vote - your feedback keeps us going!

Regards,

VikramTheGreat