Clogged Canon print head

[Grandad35]

...More probably the usual software glitch that we experience in so many areas of the computer world. Many of them require a reboot or re-installation of the software to cure the problem. Equivalent to "kicking" a mechanical device that is malfunctioning and seeing it come to life again!

I suspect that the chip on the back of the small PC board on the print head is a serial EEPROM that stores data about the print head. It's not much of a stretch to imagine that its data can get scrambled by some power (or other) glitch, and that resetting the memory cleans things up. I guess that it's not out of the question that when the printer senses an overload or overheating condition in the print head that it purposely deactivates the offending bank of nozzles. I would like to see if the same "fix" works for others, or if that post was just an anomaly.

 

[Nifty]

I would like to see if the same "fix" works for others, or if that post was just an anomaly.

Spot on!

Of course, when you're about to break open the print head or trash it, the reset of the eeprom is definitely not a terrible thing to try as a last ditch effort.

I guess someone would have to have a very specific problem and find this very specific solution before we get any kind of confirmation that it "works". Even then it could still be a fluke.

 

[Trigger 37]

Grandad35,... Thanks very much for you keen eyes and spotting this new post. I'll be happy to do the testing. I have about 6 other printheads and one of them probably has the "Picket Fence" syndrome. It is just a matter of finding the head, and the printer that goes with it.

On a different subject, I had sent you an email about cleaning HP ink carts, similar to the way you refurbish Canon ink carts. I never got a response so I have done some other experiments on cleaning out very difficult clogs on the HP -94-99 series or in fact, any HP cartridge that has a built in printhead. When the cart is virtually empty or just near that, rather than refill the ink cart, I inject hot water with a syringe. I used filtered drinking water heated to about as hot as you could drink a cup of coffee. I inkjected about 3-5ml depending on the size of the ink cart. Then I blotted the color ink carts on a hot wet paper towel, but never let it set in any spot. If you let it set, the colors will wick together and contaminate the ink inside the cartridge. I continue to blot the ink carts until I see all 3 colors good and strong. Then I put it in the printer and run alternate cleaning cycles and test prints. Once I get a decent flow of ink, I print the 3 color bars to purge the ink out of the carts. So far I'm having 100% success with this approach. There are always a couple of nozzles that just won't give up, but mostly I'm very happy with this approach.

Going back to the post above and resetting the EEprom. The EEprom that is reset is not the one on the back of the printhead. It is the main board EEprom that contains all the data that Canon keeps. The only information in that EEprom that could affect printing, is the Printhead Temperature setting. Since the banks of nozzles are divided down into groups of 128 nozzles, if a bank somehow over heats I can see this could shut down the bank. There is a position in the EEprom data that keeps track of the last printer error code. It is possilbe that these are somehow connected in the diagnostics and a section of the printhead is shut down. Hopefully I can confirm this fix, if someone doesn't beat me too it. I want to do it in a way that I document the EEprom data before and after the test.

 

[Grandad35]

Trigger37,

I got your message and did reply, but somehow it obviously got lost in the "ether".

I have never tried to clean a HP cart, so you have already progressed far beyond any knowledge that I may have on the subject.

A question on the hot water/blot technique - how many pages do you have to print to purge the water and get good color? It would seem that you would have to print at least 6-10 ml of ink to get "95% pure" ink at the nozzles.

Because HP boils a small amount of the ink to eject each droplet, consider using distilled water for the purge to prevent any minerals in the water from depositing on the nozzle heaters while the purge water is being printed.

 

[Trigger 37]

Grandad35,.. Sorry I missed your other note. It has been a very busy month. So far I have done this process on several different HP ink carts and printers. Believe it or not, with the ink cart almost empty, 2-3 ml of hot water produced great color on plain paper after two or three cleaning cycles and one or two printings of purge 3 color bars. The colors on this particular printer were not critical, only that they produced color. On the ohter printers, I printed sufficient sheets to prove there were no steaks and I had most of the nozzles clean. Then I use a syringe to withdraw all of the ink out of each color. Then I refilled each color with the correct number of ml of ink. To avoid any problem with over filling, I always use 1ml less than the max. I also have weighed all HP ink carts empty and full and I know the weight of ink by the ml. I use a very small scale that measures in grams so I know exactly how much ink to put into each ink cart.

To get the colors to come out right it is critical to withdraw all excess ink before the final refill. I think I use better that distilled water as I use water filter through charcoal filters which removes just about all minerals from the water.

This process is nowhere near as clean as what you have used on the Canon ink carts, but for what I am doing it seems to work fine. There always seems to be one or two nozzles in a given color that will not come clean, but again these are not high quality photographic printers, just everyday office or home printers.

 

[canonfodder]

For quite a while I have been running a Canon iP4200 with my home built constant ink-level CIS. See: http://www.nifty-stuff.com/forum/viewtopic.php?id=2498 Finally, I have experienced a problem with one color. The cyan started to get a scattered weakness in the Nozzle Check Print. I would run a cleaning cycle and clear it up and proceed with my printing.

Later it became necessary to do a Deep Cleaning to get the cyan to check properly. Still later it required two Deep Cleanings and finally it just stopped printing cyan completely.

I puzzled over this, lifted out the cartridge to see if I could lift the external bottle and get ink to flow, and it did. With the external bottle raised two or three inches, ink would start out the cartridge exit port.

Since wishing didn't make the problem go away, I decided to pull the print head and proceed with testing and cleaning attempts.

Using a thick walled vinyl tube that fit well over the ink inlet port, I tried to pull a vacuum on the cyan port. I use a large 60mL syringe for my vacuum pump. The cyan port would not yield at all. I moved over to the magenta port and with a fairly heavy pull, got magenta ink to come out of the head.

At this time I became worried that my unplugged cartridges might try to dry out, so I retrieved my new backup printhead from storage and installed it in the printer and set it to doing initial cleaning and then set it to doing Printhead Alignment.

Back to the clogged printhead.

With a folded towel paper pad in a shallow dish, I microwaved some water that soaked the pad and came up to a 1/8 inch depth. With the head sitting upright on the paper towel, I pulled the vacuum on the magenta input port and got magenta and eventually water. I returned to the cyan input port and pulled strongly with complete resistance until finally I got a small amount of cyan color out. This was repeated with re-heating of the water from time to time and some long waits until finally, success with the cyan port yielding ink followed by water, with a similar resistance as given by the magenta port.

I visited the other ink input ports and gave them the vacuum treatment until clear water came through. They each offered a similar resistance to that of the magenta. I decided to leave the head with water in the ink chambers for a day, so I sealed it in a ziplock bag with a wet towel paper folded up beside it. Finally I vacuumed out all the water and sealed the head again in the ziplock bag. I certainly believe the head is unclogged, but I have not run it yet.

I want to note something that I observed. Even with the head clean and unclogged, it takes a quite significant vacuum force to pull water into the printhead and out the input port. I know this is not the force caused by the restriction of the ink jet holes, because at one point I had the bottom plate of the printhead disconnected from the top plastic part, far enough to see that the little tubes that couple were separated from the bottom plate with its ink jet hole pattern. In this open condition I still got the strong resistance to a vacuum pulled on the ink input ports. I am guessing that there is some sort of extremely fine filter-like pad in the ink path, and I guess that filter, or whatever, is in the upper part below the metal screen which covers the input port. This may be not so much a filter as it is a functional part of the pumping action of the printhead. I picture the ink being restricted so it can't quickly move back with every pressure shot meant to shoot out a droplet of ink. If anyone has a distinct knowledge of this part of the print head, please let us hear about it.

I decided that I much prefer pulling a vacuum on the ink input ports as I picture anything that is clogging the ink path should not be forced down into the extremely small ink jet openings. Pulling a vaccum on the ink input port seems the logical thing to do, and it is easy to supply incoming water or other liquids by immersing just the bottom of the printhead in the liquid, perhaps aided by a soaked towel or filter paper.

 

[jflan]

Very nice post canonfodder.
I have done a similar regimen only pushed rather than pulled, heated, distilled water.

 

[Nifty]

Great post canonfodder! I completely agree with your statement regarding pulling a vacuum vs. potentially pushing a clog deeper.

 

[Tin Ho]

Canonfodder, I have done what you just did on an i960 print head several years ago. I recommend that you use a smaller syringe. A 5 ml syringe is what I use. I filled the syringe with some water and some air as well before pulling the plunger of the syringe. The water and air in the syringe make the suction a little spongy. Don't force it too hard as you may actually destroy the print head. You can pull (to vacuum the ink intake) and push (to pressurize) alternately. The spongy push and pulling is much safer for the nozzles.

If you had done this at the first sign of clogging (rather than after many cleaning cycles with more printing in between) you could have unclogged it a lot easier. At the moment the clog is cleared you will see a cloud of ink bursts out of the ink intake into the syringe with clean water in it. Continue to pull the plunger will result in a steady small amount of water being sucked through the print head into the syringe.

When you get to this state there is a 50% chance that the print head is unclogged. Remember the nozzle opening is not the only opening at the bottom end of the print head. There is still a larger opening near the nozzle. When the larger opening is unclogged the nozzles may be still clogged. At that point continue to push and pull the plunger to apply pressure and vacuum probably will not improve further. You will still need to use cleaning fluid to unclug the nozzles. The most common cleaner is Windex that contains Ammonia.

Had you done the vacuum (and pressure alternately) method at the first sign of problem you would have a much better chance to unclog it successfully without using cleaning fluid. I have had some success using the push and pull method then plugging in a cleaning cartridge overnight. Don't use a large syringe and apply too much vacuum or pressure. I destroyed a print head by doing that.

 

[canonfodder]

If you had done this at the first sign of clogging (rather than after many cleaning cycles with more printing in between) you could have unclogged it a lot easier.

Tin Ho, I have to agree with you on that point.

I did not know what I was experiencing at first, so didn't start right away on the print head. Next time I will check that a lot sooner. I did not print anything other than the simple Nozzle Check between cleaning cycles because I feared doing that might risk print head damage.

Thank you very much for your comments.