S900 prints have color cast

David C

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Hi,

My S900 has suddenly started producing prints with a distinct color cast. This happened when I changed the Cyan cartridge. I have tried a new cyan cartridge, running the clean and deep clean maintenance operations and have soaked the print head in first in hot soapy water then in alcohol. All to no avail. Throughout all of this the nozzle check has been fine.

Samples of the prints (correct and with color cast) are available at http://www.btinternet.com/~DavidG.Cochrane.

If any of the experts out there can take look and offer advice I would be very grateful.

Thanks.
 

Grandad35

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David,

Could you post your pictures on this forum? This link (http://www.nifty-stuff.com/forum/viewtopic.php?id=36) gives instructions to do this.

Many people (myself included) will not log on to Yahoo to download anything posted there.

What inks are you using? Did you just change ink suppliers?
 

David C

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Hi,

The pictures are now at (and see above!):

Picture1.jpg

Picture2.jpg


I am using third party cartidges and have been since the cartridges that came with the printer ran out. The first replacement cartridge was the same make as the empty one it replaced (i.e., 7dayshop.com). The second attempt was from ChoiceStationery.co.uk. Neither are branded.

Thanks for your help.
 

Grandad35

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Look at the second image and you will see obvious vertical bars on most areas of the image that are not present on the first image. Are you sure that these (suspiciously 1 pixel wide) bars are not an artifact introduced by your scanner or sharpening software? Make sure that they also present on the printed version.

Assuming that they are also on the printed version, these bars are evident in each of the C/M/Y/K colors, so it doesn't look like a problem with a single ink. My first guess is that you have a head alignment problem, so you should run the head alignment routine as the first step. Did you do some major maintenance when the first cart was changed that might have misaligned the print head?

If the bars are not present on the printed version, rescan them together to eliminate any scanning differences.
 

David C

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The vertical bars are likely be an artefact of the scanner - I don't have a scanner myself, so I used one in work that isn't really photo quality. All I was trying to capture with the scanner was the color difference, so I didn't scan on maximum resolution, just 400 dpi. The scanner only goes up to 600 dpi, but I'll try again at maximum resolution and post the results.

I didn't do anything else at the same time as changing the first cartridge, just pulled the old one out and put the new one in. After cleaning the print head subsequently I have gone through the head alignment routine (before printing the sample print above).
 

David C

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Hi,

I've re-scanned both photographs at 600dpi (see below). The scanner is not totally color accurate, but hopefully having a correct version and a faulty version should eliminate this factor. Certainly, there is no banding in the 'correct' picture and it is quite noticeable in the faulty version, so it isn't the scanner. And yet, the nozzle check prints perfectly and I have carried out head alignment.

I've almost resigned my self to replacing the printer - it's about 60 to replace the print head and it seems a very poor investment; better to get a complete new printer even though it means spending twice as much. But, if anyone can offer a magic solution I'm all ears!

Pic1.jpg



Pic2.jpg



Thanks,
David
 

Grandad35

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David,

Do I understand corrently that the bands are visible to the naked eye in the "bad" print? If so, are the bands along the width or length of the paper as it is printed? It is really strange that the bands are now exactly 2 pixels wide at 600 dpi (they were 1 pixel wide at 300 ppi). If the bands are present on your prints, they are almost certainly involved in your color problem.

Is there any chance that the encoder ribbon that senses the print head position is dirty? Actually, it is more likely that the encoder sensor is dirty than the encoder ribbon, since the problem exists uniformly across the entire width.

I applied a 2 pixel blur to your images (to average out any banding) and split both images into their C/M/Y/K components. On the "bad" image, the cyan is about the same, the magenta is darker and the yellow is lighter, if this tells you anything (it is almost as though the magenta and yellow carts are reversed).

You previously indicated that you already aligned the printhead. Just to be certain about this, did you do both the manual and automatic alignment steps? (At least my printer has two steps).
 

David C

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Hi,

The bands are not visible to the naked eye - the images I have posted are cropped from scans of 6X4 prints. At 600dpi they would be much too big to store in the image area for this forum. Even under a magnifying glass there is no sign of banding on the original photograph. The picture was printed in portrait format, so the vertical bands on the picture were vertical when it was printed.

I assume that the encoder sensor is somewhere at the back of the print head assembly - it certainly isn't visible without major surgery on the printer. I can't think of any reason why it would be dirty. Is there any way to clean it, without totally dismantling the printer?

I checked and the magenta and yellow carts are in the correct slots. I did swap the magenta and yellow in Photoshop and the colors looked even stranger!

On the S900 there is only one alignment step. You print the alignment patterns and then enter the numbers of the patterns that are the smoothest.

Thanks for your help.
 

Grandad35

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Since you can't see the bands under a magnifying glass, they obviously aren't there and your scanner is creating them for some strange reason. Sorry for the long side trip down the wrong road. Forget about the encoder - it's not the problem (since there is no banding). A print head misalignment can shift the colors, but you have already checked that.

How do your nozzle checks look? Are all of the colors printing properly and with the correct color? This sounds more like an ink problem than a print head problem. Did you check for cross-contamination? Pull all of your carts to see if there is any sign of the wrong color ink at the exit of any cart. It is not unknown to get an ink pulled back up into another cart, destroying the color. If you already have extra carts for all of the colors, you might want to try installing a complete new set before giving up on the printer. Cross contamination can take a while to clear from the print head, so be sure to print at least the equivalent of 3 8x10 color images before looking at the color.
 

websnail

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Really dumb question but here's a wild assed guess...

Is the scanner using any kind of descreen or other filter mode. Lord knows I see that sort of banding and noise when I try to scan newsprint or magazine copy so I was wondering if this could have a flip side effect.

Just as W.A.G though like I said so please don't mock too loudly :blush:
 

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