Bad printing of last 20% of photos on 10x15 photo paper

[ReinLemmens]

I have literally the same problem as described here:

https://h30434.www3.hp.com/t5/Printer-Ink-Cartridges-Print-Quality/Officejet-7740-always-prints-the-...

I have found an issue with the printer which is obvious but is not easily addressed.

Here's the deal. The printer prints and scans colour and B/W documents great. But photo printing on photo paper (6x4 inch particularly), is a disaster.

Not that the hardware is not capable, but I believe it's an issue with the printer's firmware.

It prints the first 70-80% of the photo with absolutely great quality, with the finishing 20-30% fuzzy. It appears that the print head failed to blend the pigmented ink after producing the first 70-80%. Here's an example of the result:

(top: original, bottom: copied on 4x6 photo paper, left part fuzzy)

I have talked to the phone support, and we have ruled out the driver issue: the effect is consistent with either windows or MAC computer, and the above picture was actually direct copied from the scanner glass with the printer's own software.

I have printed the printer quality diagnostic page with no issue found, cleaned the print head, aligned the print head, manually wiped the print head, then HP suspected that it's a print head issue (which sounds very warranted at that moment) and sent me a free print head under warranty, but did not fix the issue.

Then HP sent me a replacement printer, which produced the same result!

At this point the only thing we haven't changed is the photo paper. It's really standard Kodak 4x6 photo paper and to rule out the possibility of bad photo paper, I swapped the photo paper with plain A4, and the result is less noticeable but definitely still the same, the first 80% of the photo has good quality and last 20% is really rough.

Up till this point, there's not much I could do to keep diagnosing this problem.

It looks like a firmware issue which calculates the ink mixing parameters incorrectly halfway through a print. I am wondering if anyone in HP labs can reproduce this issue and hopefully fix it?

[Nal_NR]

Hi @ReinLemmens,

Welcome to the HP Support Community. 

I'd be happy to help you! 

Fabulous analysis. Spectacular diagnosis of the issue before posting. Kudos to you for that.

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