No print atall after cleaning print head: Canon i9950

[lewisham_phil]

Hi
My first time on this very informative forum; hope someone can help!
I've just acquired a i9950, and as there were just a few stripes on the test print, which couldn't be eradicated with a couple of deep cleans, I took the print head out, and cleaned it in line with a number of suggestions, using hot water soaked pads, and blowing through with compressed air. I put tape over the ink outlet ports on the cartridges to try and avoid any possible drying out of the cartridge sponge. I've replaced everything, and am now on my fifth deep clean, with not even a hint of colour on the test print.. is this normal? How many deep cleans does it normally take to get the ink back through?
Thanks in advance....

I'm now on my 10th deep clean, and there is still not even a spot of colour from any of the eight cartridges! Argh! what have I done!!

An update, following a further search on the forum; I'm wondering if there is a purging problem, as my ink levels don't seem to be decreasing despite 15 to 20 deep cleans. There is no ink at all getting through the heads; verified this by removing the head assembly onto a damp pad..

 

[Trigger 37]

phil,.. Take out the ink carts and cap them. Then take out the printhead and blot the bottom of the head with a damp paper towel. Check to see if you get all colors of ink. If you see ink then it is getting to the bottom of the printhead. Clean the contacts on the back of the printhead with a tissue and Isopropyl Alcohol. Then clean the contacts inside the carriage asm. ONly wipe the contact here in a downward motion as they rotate down but not up.

If you don't see ink, then you are correct, the purge unit is not sucking ink out of the ink carts and down through the prinhead. If you have done that many cleanings and the ink levels are not going down, then there could be a problem with the purge unit. Open the cover and when the head is centered pull the power cord out. Now the printhead is free to be moved to the far left and out of the way. Now use a syringe with some hot water and fill up the parking pads for the printhead. They are over at the far right. Once they are full, watch them to see if any of the water flows down to the purge tubes. It has to go somewhere. Plug the power back in and cycle the power on/off a couple of times giving the printer time to do it's normal cleaning cycle. This should suck the water through the purge unit and help to clean it out.

Open the cover and pull the power again to check and see what has happened to the water. If it is still there, you know there is a problem. If it is gone, good, you may want to repeat the water test to help clean out the purge tubes. There are about 12 things that could cause the purge unit not to suck ink up into the printheads, everything from the DC power supply, to the purge unit being stuck at one end due to accumulated ink turned to glue. Or is just may be a gear out of mesh, or a broken return spring, or a bad photo cell, or,........

Let us know what you find.

 

[Tin Ho]

Is your i9950 a new printer with a new set of OEM cartridges? If the answer is yes check the vent on the top of your cartridges. The vent is at the rear end of the cartridge originally covered by a plastic tape. The tape needs to be pulled to break the seal of the vent. If the vent is still covered under the tape ink will not flow into the print head. That's why the deep cleaning cycles did not draw any ink out of the cartridges. Trigger37 and I must be typing at the same time. Before I posted this I did not see his post. He sure gave a more complete set of things to look into.

 

[lewisham_phil]

Thanks Trigger 37 and Tin Ho for your replies.
Tin Ho, the cartridges are OEM but have been refilled, and were topped up when I picked it up yesterday, and all the vents are clear.
Trigger 37, there is no sign of any ink atall getting through the heads after checking with a damp pad; the cartridges are full, and the ink seems to be free running; atleast if I squeeze the cartridges, a drop of ink is expelled.
I have had a go at filling the parking pads, but they have so far taken three syringes (total 30ml) of water and it keeps soaking away. When you say 'fill up' the parking pads, do you mean keep filling until it is puddling on the surface, or will it only do this if there is actually a blockage? If it keeps soaking away do I assume that it is not blocked? Is there a danger of me filling up the ink waste tank?!
I have done a deep clean and test print, and still not a dot. I notice that the pads look like they haven't pulled any ink through, as particularly the left hand pad is white, as it was after cleaning with the syringe.

 

[Trigger 37]

phil,.. Ok with the testing you have done, and you still do not see any ink getting to the printhead, the purge unit is not sucking ink. It is OK that the ink passes through the pads. That is what is shoud do. However to suck ink, like I said in my note, there are 10 other things that can cause it not to suck ink. One of the gears could be jammed and therefore the entire purge unit won't turn. If you go to your print driver and select properties and pull up the "maintenance" window and do a cleaning cycle, do you hear the mechanism churrning inside as if it is trying to do the purge cycle. Do any of the noises sound funny, grinding, or anything like that.

I think the next thing for you to do is to take the unit apart and check the purge unit and test it. I do not have the i9900 or i9950 printer Service Manual. But as far as I can tell, the i9950 is just a wide format 8 color ink jet printer. That is a lot of ink to manage. Th inside guts of the printer, and the purge unit are not any different from any other Canon printer.

You may want to find some local Canon Service facility. While this printer looks very much like a Wide Format version of the Canon i960, I'm not sure my manual for the i960 would give you sufficient information to take the prinet apart.

 

[lewisham_phil]

Yes, it is looking like a purge unit problem; so tonight I removed the covers, and had a closer look at the purge unit. Removing the two purge head pads reveals four outlets; the two at the front lead straight down into the waste sump, while the two towards the back lead to the purge pump. It's worth knowing this before you empty copious amounts of water directly into the sump as I did!
I used a syringe to pump hot water back up the purge pump outlet tubes, which passed through easily, and without much ink colouration, which surprised me. It is easy to pop the small tubes off the back of the purge head doing this, if to much pressure is used. The purge head movement seems to work, if I rotate the motor manually. Is there anything else I can check while I'm in there?
Otherwise, I might reassemble it tomorrow, and try temporarily blocking the direct drain holes in the purge head, so that I can then fill them up with water and see what happens.

 

[Trigger 37]

phil,...Leave the printer out of the case and reconnect all the tubes of the purge unit and the pads. The metal frame has some feet on the bottom and you can elevate the entire chassis using some small wood blocks. Arrange things such that you can reconnect all the cable that you disconnected. I don't think it matters that the cover is open, but you can find the cover switch and come up with some way to tape it down so the printer thinks it is all back together.

Put some folded paper towels under the clear exit tubes from the purge unit. Be carefull not to block the downward movement of the pads. This is part of the purge cycle and they need room to drop the pads out of the way of the printhead when it moves back into position. Re-install the printhead and all the inks. Turn the printer on and from your PC force it to do a cleaning cycle. You can watch all the cycle of the purge unit and see any ink that is sucked out. The cycle looks like this; The white locking lever will drop down and the pads will drop down and the printhead will move away. Then the wipers will travel forward and back. If the printer thinks the top cover is closed it will park the printhead over the pads after 55 seconds. Once it is there, you can do the Cleaning cycle. The purge unit will raise the pads to the bottom of the PH and then the drive motor will turn for several revolutions. It sucks black ink in one direction and then reverses and sucks colored ink while turning in the opposite direction. You want to watch all the gears that are inside of the purge unit and especially the spring that pulls the wipers back away from the printhead.

You can watch all of this cycle when the power is off and the printhead is move away by turning the large white gear away from the front of the machine. Turn it slowly and you should see the pads drop down, the locking tab drop down, the wipers come forward and then get pulled back by the tension of the spring. I have had purge units go bad because one of the gears came out of connection, and another one the spring popped off and the wipers would not come back, and another one where the locking tab spring was missing. I finally found it in the bottom of the printer. There are also photocells in the back bottom of the purge unit that monitor the cams that turn durning the cycle. This tells the printer that the purge unit is doing its cycle. Since you're not getting any error messages all of this should be working. YOu could have an air leak in the pump or just a bad pump.

Put some more water on the pads and manually turn the white gear and see if the pump sucks the water down through the tubes to your paper towel. Now that you have it apart, you can see everything. Lets us know what you find.

 

[lewisham_phil]

Thanks Trigger37, and congrats on the big 300!
Right, it is almost certainly the purge pump; all the parts go through the motions, wipers go to and fro, but nothing coming out of the purge tubes. To make certain, I removed the two pads from the rubber purge head, blocked the direct drain holes with two small lumps of bluetack, and filled the rubber head with water. I did a deep clean , which runs the purge pump for approx 10 seconds, (you can see the drain tubes oscillating slightly during this time, so the motor is trying to do something). However nothing was pumped away, the two rubber wells still full of water.
Do you know what type of pump this is? The ability to push water back up the outlet tubes with a syringe seems to depend on what part of the cycle the purge routine is on, though it never comes up as far as the purge head, but comes out at port or leak somewhere below (unlike I suggested in my last post).
I am rather resigned to replacing the purge unit, so I shall dismantle this one if I do, unless you think there are any last ditch ideas on how to revive the pump!
Any recommendations of parts suppliers in the UK would be appreciated..

 

[mikling]

usually the purge pump is a peristaltic pump which is a positive displacement pump. The action works the same way our intestines work by a moving squeezing motion. The construction is usually quite simple consisting of a set of rollers that rotate and squeeze the tubing thus pushing liquid out of the tube. Imagine a garden hose that is filled with water. An automobile wheel then runs along the length squeezing the liquid out. Keeping in mind that what goes in must come out and thereby the vacuum or sucking action. These pumps are quite accurate and used extensively in dispensing and medical applications.......in which case you can see that the simplicity leads to reliability. Generally either the motor is not working or the tubing is either broken or cracked and replacement of the tubing or motor is all that is necessary.

 

[Trigger 37]

Phil,.. I listed some very specific things to do. From reading your note I can't make out if you did them. Are you saying you elevated the chassis and put a paper towel under the purge tubes, and ran a deep cleaning cycle with printhead installed and ink installed and you "GOT NO INK TO COME OUT OF THE TUBES ONTO THE TOWEL." Yet all the parts of the pump went through the cycle.

Your test of blocking up the holes under the pads only proved "That if you block the drain in a sink, the water will not flow"

You need to prove your purge pump is not working. All it could be is a total block inside the pump. To prove this you need to see something come out of the purge unit tubes onto a paper towel. Leave the PH and inkcarts installed and again, fill the pads with water. Then run two or there Power ON/Off cycles. YOu should see the water come through the exit purge tubes onto the towel. Use very hot water from you sink. If there is a clog inside the pump this will help dissolve it.