Need Help OCE 250GT print issue and do PTFE Micro Filters affect meniscus level?

[UGCalgary]

Our old but well maintained 250GT now has a strange printing issue. We had Canon replace the two yellow print heads recently and immediately had an issue where the yellow ink starts to drop out after printing about 20-25 cm of a full bed with heavy yellow coverage.
If you stop the print and do a nozzle check it is fine. Somehow the yellow printheads are getting ink starvation while printing?
We did notice that when the machine is idle the ink meniscus level on the popup ink screen fluctuates from 12.1 down to 10.7 and then back up to 12.1.
The Canon techs were in for several days trying to find a fix with no luck. Still waiting for a full service report as to what was checked/changed. More on that later.
What is interesting is that on the schematic of the ink and vacuum system for this printer all the plastic PTFE micro filters are specified to be the 0.2 micron version.
However, there are 0.2 micron filters on the black and cyan purge valves and 0.45 micron filters on the magenta and yellow purge valves. Also, the PTFE filters inside the cavity behind the black ink filters are also 0.45 micron.
Only the Canon techs have been in to change those filters over the years.
Does anyone know if it is critical that these all be the 0.2 micron filters? Could a possible vacuum imbalance cause this issue of ink starvation only on the yellow?

 

[AlsEU]

Did the tech check/set the meniscus vacuum level and time of change with the external gauge? How old is the yellow ink pump? Was it replaced?

 

[edcooleyar]

Be sure the meniscus filters are new and to spec. That is a wide meniscus fluctuation but most likely not your problem. You can watch the ink screen during printing. If the yellow goes low and stays that way for more than a few seconds you probably have a weak pump.

 

[Select Bulgaria Service]

Our old but well maintained 250GT now has a strange printing issue. We had Canon replace the two yellow print heads recently and immediately had an issue where the yellow ink starts to drop out after printing about 20-25 cm of a full bed with heavy yellow coverage.
If you stop the print and do a nozzle check it is fine. Somehow the yellow printheads are getting ink starvation while printing?
We did notice that when the machine is idle the ink meniscus level on the popup ink screen fluctuates from 12.1 down to 10.7 and then back up to 12.1.
The Canon techs were in for several days trying to find a fix with no luck. Still waiting for a full service report as to what was checked/changed. More on that later.
What is interesting is that on the schematic of the ink and vacuum system for this printer all the plastic PTFE micro filters are specified to be the 0.2 micron version.
However, there are 0.2 micron filters on the black and cyan purge valves and 0.45 micron filters on the magenta and yellow purge valves. Also, the PTFE filters inside the cavity behind the black ink filters are also 0.45 micron.
Only the Canon techs have been in to change those filters over the years.
Does anyone know if it is critical that these all be the 0.2 micron filters? Could a possible vacuum imbalance cause this issue of ink starvation only on the yellow?

1. All meniscus filters must be 0.22 microns. Not 0.45 and not mixed.
2. The mebiscus vacuum must be measured and adjusted. We have tool for this. To adjust the level is not enough. You can see 12 in UI, but

Our old but well maintained 250GT now has a strange printing issue. We had Canon replace the two yellow print heads recently and immediately had an issue where the yellow ink starts to drop out after printing about 20-25 cm of a full bed with heavy yellow coverage.
If you stop the print and do a nozzle check it is fine. Somehow the yellow printheads are getting ink starvation while printing?
We did notice that when the machine is idle the ink meniscus level on the popup ink screen fluctuates from 12.1 down to 10.7 and then back up to 12.1.
The Canon techs were in for several days trying to find a fix with no luck. Still waiting for a full service report as to what was checked/changed. More on that later.
What is interesting is that on the schematic of the ink and vacuum system for this printer all the plastic PTFE micro filters are specified to be the 0.2 micron version.
However, there are 0.2 micron filters on the black and cyan purge valves and 0.45 micron filters on the magenta and yellow purge valves. Also, the PTFE filters inside the cavity behind the black ink filters are also 0.45 micron.
Only the Canon techs have been in to change those filters over the years.
Does anyone know if it is critical that these all be the 0.2 micron filters? Could a possible vacuum imbalance cause this issue of ink starvation only on the yellow?

So...
1. All filters must be 0.22 microns. With 0.45 you change the droplet size. Also change the vacuum settings if there were any.
2. The Canon colleagues should have a device with which they can try to adjust the vacuum and equalize the value you see with the real value.
3. If you have degas modules, you should remove them and replace them with a simple hose. You simply have a loss of vacuum or the vacuum is not adjusted.

Often the reason for this can be the head. Do a purge and see if there is a head that does not leak like the others.
4. Carefully inspect the black hoses between the head and the subtanks. It often fails.
5. If you wish, find the group on FB Canon Oce Arizona Printers. It will be easier for me to guide you.