flatbed scanner calibration/optical reference failure

[C_Slate]

1. Solid dark vertical line on the left edge

2. Skewed shadow line along the top edge (slants downward rightward)

Purchase Date: November 25, 2022

Warranty: Expired

Cause

• Failure of the flatbed white shading reference used at scan start

• The CIS performs calibration while the carriage is slightly in motion

• Because the reference reflectance is no longer uniform, the firmware applies incorrect gain correction across time, producing:

  • Vertical compression of the first scan band

  • A slanted shadow line instead of a straight one

This is why:

• Text at the top appears “squashed”

• Gray and B&W exaggerate the issue

• Restarting and cleaning did not help

This printer only lasted less than three years.  HP quality has degraded dramatically after experience with this product.  It also jams in the feeder and tries to feed multiple documents at once, as much as three documents at a time intermittently.  Truly disappointing!

[Kuroi_Kenshi]

Hi @C_Slate,

Welcome to the HP Support Community! We're stoked to have you on board! 

To help us get started on resolving your issue, could you please share the model name of your device?

We're looking forward to helping you get back up and running! 

Best regards,

[C_Slate]

This is the product I have, Kuroi Kenshi.

CN28B57111

HP Smart Tank 7301 All-in-One

[Kuroi_Kenshi]

Hi @C_Slate,

Thank you for the response.

I understand your flatbed scanner is producing a dark vertical line on the left edge and a skewed shadow line along the top, which points to a flatbed calibration/optical reference issue. Let’s go through a few steps to check what could be causing this and what can realistically be done.

Power reset to force full scanner recalibration
Turn the printer off, unplug the power cable from the rear, and disconnect it from the wall outlet.
Wait at least 60 seconds, then plug it directly into a wall outlet (not a surge protector) and power it back on to allow a fresh CIS calibration cycle.

Inspect the flatbed white reference strip
Open the scanner lid and look closely at the thin white strip along the top edge of the flatbed glass.
Check for yellowing, gray shading, scratches, adhesive residue, or uneven discoloration, as any non-uniform reflectance here will cause gain correction errors.

Clean the scanner glass and reference area precisely
Use a lint-free cloth lightly moistened with glass cleaner or distilled water.
Clean the entire glass surface and the white reference strip carefully, then dry fully before closing the lid.

Check for shadowing caused by lid or backing foam
Close the scanner lid slowly and ensure it sits flat without gaps or warped hinges.
If the lid backing foam is damaged or uneven, it can introduce slanted shadows during the initial scan band.

Test scans using different modes
Perform one color scan and one grayscale or black-and-white scan of a blank white sheet.
If grayscale and B&W exaggerate the distortion, it confirms incorrect CIS gain calibration rather than a software issue.

Verify flatbed vs ADF behavior
Scan the same document using the flatbed and then the document feeder.
If the defect appears only on flatbed scans, the CIS reference failure is isolated to the flatbed optical path.

Address ADF multi-feed and jam behavior separately
Clean the ADF pickup rollers and separation pad with a damp lint-free cloth.
Worn or glazed rollers commonly cause multiple sheets to feed at once, especially on devices over two years old.

I hope this helps.

I'm glad I could help! 😊 If this resolved your issue, please mark it as "Accepted Solution" and click "Yes" on "Was this reply helpful?" Your feedback not only keeps us going but also helps others find the solution faster! 👍✨

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Best regards,

[C_Slate]

Hi Kuroi,

I have read your troubleshooting steps and actions.  These are the actions I conducted to narrow down the CIS reference failure.  B&W and grayscale both are skewed, but the color mode is not.  Right now, I can only use the feeder for non-color prints.

It is disappointing as my Epson Printer lasted nearly 10 years before I replaced it with this HP model.  This product only last less that 3 years before suffering a depot level repair requirement.

I appreciate the guidance, but I plan to replace it in the near future.

Sincerely,

Chris

[Kuroi_Kenshi]

Hi,

Welcome to the HP Support Community! 

We're here to help you tackle that hardware failure! Don't worry, we've got your back! 

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We're looking forward to helping you resolve this issue! 

Stay tuned, and thanks for your patience! 

Best regards,