Win the Sherlock Holmes award

[D3D]

After a half a year of struggling with white inks we decided to replace the three most problematic white print heads on our Arizona 2280 (only 1 shown here). With some remote support we did the job ourselves, having never done it before it was moderately challenging but everything worked out just fine. The trouble is a main problem we thought we were fixing is still present. HOW!!!??? You can see in the image that these areas of missing nozzles are the same for the replaced print head and the new print head. The underside of the carriage is clean, no boogers of any kind, we are pretty clean shop and take care of things in general. Is this electrical? A ribbon cable? Something messed up on a board? We can get a 100% perfect nozzle test with some cleaning and purging. Also if it goes out mid job pressing the pause button and waiting a minute seems to get us back most of the time. I will get a tech in if I have to but I am hoping someone here has seen this before and can offer some insight.

 

[AlsEU]

Take a quick look inside the carriage and compare the position of the missing nozzles with the ink connection tube at the top of the head. Older versions of Arizona had a similar problem on the white channels - ink flows into the head and leaves some sediment on the internal side of the nozzle plate directly under the tube. In time the sediment layer grows - the white circulates in the tubing, but a portion inside the head remains motionless. The white pigment is the heaviest of all colours (due to the titanium used for the production) and sediments in the shortest time.
You may try to flush the head using the syringe and the IPA (not the flush, it won't dissolve the sediment) from time to time or clean the nozzle plate with the IPA (a small amount may be sucked into the head through the nozzle and it may help). If you use IPA on the nozzle plate, before the test print make standard cleaning using ink - IPA removes everything from the nozzle plate and printing requires a thin layer of the ink on the nozzle plate. Without it the test print after IPA cleaning will be worse than before...

 

[D3D]

Take a quick look inside the carriage and compare the position of the missing nozzles with the ink connection tube at the top of the head. Older versions of Arizona had a similar problem on the white channels - ink flows into the head and leaves some sediment on the internal side of the nozzle plate directly under the tube. In time the sediment layer grows - the white circulates in the tubing, but a portion inside the head remains motionless. The white pigment is the heaviest of all colours (due to the titanium used for the production) and sediments in the shortest time.
You may try to flush the head using the syringe and the IPA (not the flush, it won't dissolve the sediment) from time to time or clean the nozzle plate with the IPA (a small amount may be sucked into the head through the nozzle and it may help). If you use IPA on the nozzle plate, before the test print make standard cleaning using ink - IPA removes everything from the nozzle plate and printing requires a thin layer of the ink on the nozzle plate. Without it the test print after IPA cleaning will be worse than before...

Thanks I will check it out when I am back in tomorrow, I see the logic to what you are saying. I will be disappointed if that is the case though, seems like print heads less than 2 weeks old should not have any sediment.

 

[D3D]

Wow, I can't believe it. What a design failure to kick forward for so many generations of printheads. It looks like you are correct, there is block of nozzles that commonly go out that are perfectly in line with one of the tubes. How is it you know this to be the case, have you worked as a Canon tech?

 

[AlsEU]

If you see this problem two weeks after the head replacement, maybe you need to consider the ink system flushing to remove sediments from tubes, pumps and so on. And an important question - when did you replace the ink filters for the last time?

 

[D3D]

We did a complete flush 2 months ago when we changed white ink brands. Replaced the filters at that time as well. One thing we notice is that we get low reservoir notifications on the white inks, after a purge of course but also sometimes during a print. Is there anything related to the ink pumps that could be a factor?

 

[AlsEU]

White ink pumps are always the most tired due to the ink weight. Look around the pumps, maybe there's a black powder around (if it's there, the brushes are approaching the end of their lifetime. Newer machines have brushless pumps, I'm not sure which version you have. Did you replace the main ink filters or these in the carriage?

 

[JamesLam]

AlsEU, maybe Canon should have you in for some training (to train their techs and service peeps).

 

[D3D]

White ink pumps are always the most tired due to the ink weight. Look around the pumps, maybe there's a black powder around (if it's there, the brushes are approaching the end of their lifetime. Newer machines have brushless pumps, I'm not sure which version you have. Did you replace the main ink filters or these in the carriage?

We replaced the ink filters by the bags and the 2 white reservoirs, on this machine there are no filters in the carriage. I don't see any black powder but don't know what motors are being used either.

 

[AlsEU]

Did you measure the meniscus vacuum using the external gauge? Did you replace the small filters inside the carriage, in the vacuum tubing?

 

[D3D]

Did you measure the meniscus vacuum using the external gauge? Did you replace the small filters inside the carriage, in the vacuum tubing?

No, meniscus has not been measured. Did not see any ink in the meniscus filters and did not replace. Ours reads below 18 on screen pretty routinely, but I know that is not generally accurate.