fuzzy (or blurry) print HP Deskjet 970

Paul W.

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First, my document has two kinds of print, one is plain text, one with color, red or blue, headers.

Here's what's strange:

In the normal print mode, the text is fuzzy and the headers are fine, in red or blue. The headers are not simply an enlarged font, they must be graphics of some kind.

In the best print mode, the text is fuzzy and the headers are ok, just a little more clear than normal.

In draft, the text is fine but the headers are fuzzy.

(I did a search first, but perhaps I searched incorrectly, couldn't find this topic.)

Any tips would be appreciated, thank you!
 

PeterBJ

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Could you please upload a crop from a scan or photo of a document showing the defects? It's said that a picture is worth more than a thousand words and that is certainly true when discussing printer problems.

The HP Deskjet 970 is a two cartridge printer using the type 45 pigment black and type 78 tri-colour cartridge. I think the printer uses bi-directional printing in normal and best mode and uni-directional printing in draft mode. If a printer can use bidirectional print mode the print head(s)/cartridges most like have two nozzle rows for each colour and black.

If one row of the black nozzles is partially clogged or distorted the result could be fuzzy print in normal and best modes. In draft mode uni-directional printing might be used, meaning only one nozzle row is used. If the nozzle row used is the good one this explains why text is not fuzzy in draft mode.

If one set of nozzle rows in the colour cartridge is partially clogged this could cause bad quality print in draft mode if the partially clogged nozzle rows are used.

I think it is a cartridge problem so what kind of cartridges do you use? New OEM? Remanufactured cartridges? Or cartridges refilled either by yourself or a local refill shop? I admit that a set of new OEM cartridges is very expensive, but maybe a "new" set of remanufactured cartridges would also cure the printer?

Maybe cartridge alignment and positioning errors also contribute to the problem? You could try cleaning the timing/encoder strip with a window cleaner with ammonia on a piece of soft tissue paper. Also do a re-aligning of the cartridges by opening the printer as if you would change a cartridge and remove and reinsert one of the cartridges and close the printer. This should trigger the alignment procedure.

Maybe you can unclog the probably partly clogged cartridges by alternatively pushing the nozzles against a soft tissue paper moistened with a window cleaner with ammonia for instance the "Original Windex with Ammonia-D" and a dry soft tissue paper. This cleaning and the encoder strip cleaning is worth trying before ordering new or remanufactured cartridges.

My suggestions are guesses based on my experiences with similar HP Deskjet models using the same or similar large cartridges. A scan or photo showing the printing defects would increase the chance of finding the cause of the problems.
 
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Paul W.

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Excellent answer, Peter. I think I should have posted my question at another time! Why do I say that? We have family and out of town guests in abundance right now and I may not have time to try your suggestions. First, posting a photo is where I should start.

So bear with me a few days, I may not be able to give your post a worthy response(s)!

Regards,

Paul
 

PeterBJ

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First, posting a photo is where I should start.
What kind of cartridges, new, commercially remanufactured or home/shop refilled you use, is also very important. So please an answer to that question.
 

Paul W.

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Found a window of time here to address a couple of your suggestions...

Attached is a photo of a sample of a photo taken with the printer in Normal mode. Ignore the out of focus quality of blue type, I was holding the camera too close. It's a lot sharper in reality. But as you can see in the black type, there's kind of a shadow effect. That's what I'm concerned about. Why doesn't the blue have that shadow, I'm wondering. The Best option is similar but not as pronounced. Currently we have the computer print menu set to Draft and that's the best of the three, no shadow on the blue or black type.

To your question on the cartridge, it's the commercially remanufactured variety.

IMG_0908.JPG


That's all I have time for this am. Again, very sorry I can't get at any of your other excellent suggestions. Stay tuned, may be a while!

Paul
 
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PeterBJ

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Your photo clearly shows the "shadowing" of the black text. It is hard to determine but has the shadow got a reddish or magenta cast?

I think the problem is caused by a defective cartridge. I have experienced something similar with a HP DJ 930 with cartridges I had refilled. Sadly I don't remember if the black or tri-colour cartridge caused the problem. I think a set of "new" remanufactured cartridges is needed.

But before ordering another set of cartridges you could try forcing an alignment of the cartridges by opening the lid, removing and reinserting one of the cartridges and closing the lid. If this doesn't help then try cleaning the timing/encoder strip with a piece of soft tissue paper moistened with a window cleaner with ammonia. Open the lid as if you would change a cartridge. When the cartridges are in the change position pull the power cord without first turning the printer off. You can now slide the cartridge carriage from side to side so you can get access to all of the timing strip. Be careful not to tear the strip.

If aligning the cartridges and cleaning the timing/encoder strip makes no difference then please do a tap 84 test and take two photos of the print, one showing the black part and one showing the colour part. Here is a list of "Tap tests" for the DJ 9xx series printers.

Here is a "Tap 84 test" almost perfect with only a few missing black nozzles. Click to enlarge:

HP DJ 9xx tap 84.jpg

The HP DJ 9xx series of printers are almost 20 years old, so maybe finding good remanufactured cartridges is difficult?
 

Paul W.

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Thanks to your suggestions, everyone. Finally (a month later!) I got around to this project, incorporating some of your ideas. What worked was:

-> Cleaning the timer/encoder strip using some lintless paper towel and alcohol (didn't have any window cleaner with ammonia handy.)
-> replacing the color cart with a new one. (The old one was 69% full, and I tried pressing a hot water soaked paper towel to the nozzle.)
-> cleaning the nozzle of the black cart

Regards,

Paul
 
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