problems with image after replacing tanks on iP8720

jal

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Maybe not...? When I said problem solved after installing the Canon cartridges, I had printed the same photo above (Venice gondolas) and it was fine. Today I printed a different photo, except used plain paper (for reasons not relevant here - I always use photo paper if I want a quality photo print), and the the gray verticals lines were back in the black areas. When I printed it with photo paper, the lines were gone. Seems obvious there's something about the paper, I guess?
 

PeterBJ

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The media setting determines which black ink is used. For plain paper setting the pigment black ink in the large black cartridge is used. For all other media settings the dye (photo) black in the small black cartridge is used, So the problem is caused by the ink or printhead, not by the paper.

Make sure the tape covering the vent on the pigment black cartridge is removed and try cleaning the nozzles. It is only necessary to clean the Pigment black nozzles, You don't need to clean the dye nozzles.

You could also check that the pigment black cartridge can deliver ink by holding it over a sink or holding a paper towel under the ink outlet and blowing gently into the vent. It should be east to expel a drop of ink. Else there is a problem with the cartridge.
 
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jal

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PeterBJ, I hadn't seen your reply until now. But since my last post I'd printed a couple of photos on photo paper which both came out very nice. I resolved to just not use plain paper. Then today, before seeing your post, I printed a photo on photo paper which had the vertical stripes again, both in the blacks and in some darker colors - browns. The photo I printed was one my wife wanted me to print that she found online - she emailed it to me. I cleaned the nozzles and then tried printing the gondola photo again and it was fine - blacks were good, not a trace of the stripes. Looked at your post and I understand the problem is not the paper and my experience printing the photo from an online source confirms that. Now I am wondering if there is something about the photo from the online source that explains why it had the stripes in the black.
 

PeterBJ

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.........Now I am wondering if there is something about the photo from the online source that explains why it had the stripes in the black.
I don't think the source of the photo makes any difference. I think the striping is caused by ink starvation because of a high demand for photo black ink in large black or very dark areas.
 

jal

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I have appreciated all of your input and have learned some things about the iP8720. I am a novice concerning this technology as I am sure is obvious. Forgot to say that, yesterday I did take the photo black cartridge out and blew into the vent (the Y shaped opening) and nothing came out onto the paper towel which must prove your conclusion about ink starvation. But this morning I printed a 4x6 photo on photo paper of Christmas lights on a house at night - image is almost all black - and no stripes. I remain a bit mystified despite your best efforts to educate me. Thanks again.
 

PeterBJ

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It looks to me like there is probably an intermittent ink starvation problem with the CLI-251 BK cartridge. Is it really a new Canon OEM? Not an aftermarket cartridge or a remanufactured cartridge?

Here is scan of Canon OEM cartridges, notice Canon logo and a thin brown phenolic chip. Yours should look the same except the cartridge should be marked CLI-251 BK or CLI-251 XL BK. Click to enlarge.

CLI-551 BK OEM.jpg

Most aftermarket PGI-250/CLI-251 cartridges are made from transparent plastic and the chip is thicker and made from red or green epoxy/fibre glass material. There are however aftermarket cartridges that are black and look very much like OEM cartridges.
 
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jal

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The cartridges I have are definitely Canon OEM. They have the Canon logo on both sides and on the top as in your scan, and the brown phenolic chip. Got them at B&H - at a price I would expect to pay for OEM.
 

PeterBJ

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I agree that your new cartridges must be genuine Canon. Sadly I cannot figure out then what causes the seemingly intermittent ink starvation.
 

jal

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Thank you for all your attention to this and the help you have provided.
 
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