i560 & MP730 nozzle test is wierd

[Trigger 37]

I've got some printer problems with my MP730 printhead and I want to post a picture of the nozzle test pattern to get some help from others in figureing out what could cause these patterns. I've looked for a "Help" folder on this web site but can't find one. I need to know how to post a picture or to set up a link to a picture. I see others have set up such a link but I don't know how to do it. Hope someone will set me straight.

As far as cleaning the printhead, I've done it a dozen different ways and the pattern shows no improvement. It is the standard cross bar or ladder print that canon uses in most printers. Mine is just printing or not printing in places is should. When it fires specific nozzles the ink wanders around in a curved pattern but eventually gets to the place it should have been. I even prints dots ahead of where the printing is supposed to start. It would be much easier for you to help if you could see the close up picture I've taken with my Digital Camera.

I see the http and the img buttons but there is no way to paste a picture inside the message. I know there is a way, I just haven't learned it yet.

 

[mikling]

Many times when the jet is weak, it is either due to clogs or ink feed issues from the carts.
If you have refilled many times and use the printer regularly, you would then suspect ink feed issues.

 

[Lilla]

I see the http and the img buttons but there is no way to paste a picture inside the message. I know there is a way, I just haven't learned it yet.

First upload your picture by following the instructions at this link

Then add a link in your post to your picture.

For example:

[img]http://www.nifty-stuff.com/img/files/mypicture.jpg[/img]

 

[Trigger 37]

Lilla,

Thanks for the info. I knew it had to be something like that.

Ok, here is the problem,.. the Magenta prints very weird patterns. It does things that logically seem impossible,...like printing dots before the time has come to start the pattern,... or printing curved lines instead of straight lines. If it is really a clogged nozzle, and OH yes,.. all print head are made up of individual nozzles and each one can be fired independantly,... how could it do these kinds of things. The first picture is of the first part of the Magenta pattern. The second picture shows the first part of the Cyan and the Magenta. You can see all the nozzles of the Cyan (except one) print great and in straight lines. The black pattern in also perfect,... not one error. The pattern, or commands to create such a pattern are the same so it is not the electronic signals to the head that are bad. I should also mention that I have moved this head to my Canon i560 printer and since the nozzle test pattern is different on that printer the Magenta comes out with missing lines in a solid bar of Magenta.

On the top left corner of the pattern you see that the majority of all nozzles fire at once and that produces the vertical magenta line. The you see a curved line coming up from the second horizontal line to finish making the first top horizontal line. This is nozzle number 1 on the magenta head and you can see it completes about 90% of that line. Now I know the paper did not move in that crazy curved pattern, and physically the nozzle didn't move,.. so how could the printer make such a pattern. Here is the same pattern in Cyan so you can see how straight it is. In the third row and the 6th line down you will see that one of the Cyan nozzles did not fire. After a couple of head cleaning cycles that was fixed.

You will see in other parts of the Magenta image that there are several nozzles that do the same thing and repeat over the entire width of the test. None are exactly the same as any other, except that the same nozzle always makes the same curved pattern starting at each vertical line. This is the point where all nozzles are fired at once.

If the first curved line is really nozzle #1 firing as it is supposed to fire,... how does it get all the way to the top of the 2nd horizontal line and make its way up to the first horizontal line where it should have been. Nozzles don't move. Heads move, and paper moves. If a nozzles in clogged and partially sprays out dots,.. they would be very close and random,... not 100% repeatable. If it really is something to do with the electronics, it is in the printhead as this problem travels with the printhead to another machine. I did not include the photo of the "light Magenta" nozzles test pattern, and that may be even a bigger clue. Similar curved lines occur from that printhead and it is completely different from the Magenta head. It only shares the same ink source. I have mentally rulled out any broken wires since if any wire was broken, an entire group of nozzles would not function since they are all address selected in binary code,.. just like a memory chip. There has to be a decoder chip inside the printhead since there are 512 Cyan and Magenta nozzles and 256 yellow. However, if you look at the bottom of the printhead there are 5 colored rows of nozzles,.. this means 256 in one row each for C,N,Y,Pc,Pm, nozzle test pattern prints there are 5 colored row, C,M,Y,Pc,Pm, in that order. Again, if any decoder was shorted or broken, an entire section of the pattern would be missing. Nothing I know of electrically could cause the unit to print curved patterns. In looking close at the entire pattern, it appears as if all nozzles fire at some point in time at some location.

I hope someone has some idea. Thanks
I just wish that someone from Canon or a trained Canon rep followed this web site. They could tell me in a minute what could cause this. As more information to others, I have tried dozens of cleanings, full power air compressor at 90 psi, I have used a syringe full of Windex and a 1/4" straw to force Windex down through the filter screens in the printhead. Nothing has ever changed the Magenta pattern.

If I don't get some good help from this forum I'm going to do the complete head disassmbley I found in this forum. I haven't done it yet because I had convinced myself it could not be a clog. My other choice is to just live with it and don't every use that printer for color prints.

 

[Grandad35]

Trigger 37,

Here's my theory on what you are seeing.

Each ink color has two columns of nozzles (you can see them when you look at the bottom of the print head). One column is apparently acting properly, but for some reason the ink from some nozzles on the other column is being deflected sideways after it exits from the nozzles. Imagine what would happen if there was a buildup of ink residue on one side of a nozzle - the ink "bubble" would not release from all areas of the nozzle opening at the same time and would shoot off at an angle. This process would be somewhat repeatable, so the ink from a defective nozzle would always have approximately the same offset on the paper.

If this is the case, the head probably isn't clogged in the traditional sense, so a disassembly wouldn't help (as you already surmised). I would concentrate on trying to clean the exit areas of the nozzles. I have seen photos where this area can be scratched by a paper towel, so start by setting (not scrubbing) the head on a folded paper towel soaked with an ammonia based window cleaner. If you have a strong magnifying glass, try looking at this area to see if it is damaged in any way (e.g. chipped corners on the nozzles exits).

Is the printer still under warranty? Did this problem appear suddenly, or was it there from when the printer was new? If it appeared suddenly, did anything unusual preceed its appearance (a child fed a sheet of peanut butter covered paper through the printer, etc.).

Any other suggestions on how to clean the nozzle exits?

 

[Trigger 37]

Grandad35, Thanks for your suggestions. It is long out of warranty, but abosolutley everything else works. The MP730 is quite a nice fax unit that can copy pages at 22ppm in great black print.

You are right about the dual print head. Just about all of the Canon 3 color+Black printer have 5 color heads,... C,M,Y,Pc,Pm. Instead of including 5 ink color carts, they add an extra row of head for Pc & Pm. These heads are set to release 1/2 as much ink in each drop as the C,M,Y head. This gives them the effect of Photo Cyan and Photo Magenta. When you print the nozzle test pattern you get a pattern for each head + the black head. The pattern is the same size as the head, so Maintenance can trace bad nozzles.

I've check the head with the magnifying glass I have (which is not great) and can't see anything. These nozzles are smaller than a human hair. In my long -long note I pointed out that the Magenta head and the Photo magenta head both have these unexplained curved lines that start in the wrong place about 1/16" below where they should be and as the head moves across the paper the ink dot curve up to the line where they should have been, which is 1/16" higher and 1/32" farther over to the right.
Also, the Magenta head and the Photo Magenta head are separated by the Yellow head and that puts them about 3/8" apart.
Any nozzles that was defective or had some clog would "Spray poor dots" each time it was fired. These dots are the right size but just in the wrong location. The distance these dots move is about the space of 16 nozzles,... way to far for such a small 2 picoliter dot to fly. Look at the picture again and see if you agree.

I'm going to call Canon and ask them if I can fax the picture to them. The will never allow anyone to email them a picture because they are affraid what they would get. I guess they won't allow a fax either. I wonder about the mail. I think I will also locate a good local Canon repair person and fax them the picture and see what they say.

Maybe someone else has some ideas.