#1: Canon Pixma CIS's - overpressure Author: Martin, Location: South Yorkshire, UKPosted: Sat Sep 29, 2007 8:32 pm — I've been trying to find where I may have discussed this in the past but had no luck so I thought I'd start a new post with a "fix" for Canon Pixma CIS kits.
The problem I've been seeing has been bugging me now for over a year and was made significantly more difficult to nail down because of the sheer number of variables involved in a CIS kit in this sort of printer. For instance the size of the exit port and the poor air seal between cartridge and port create one set of problems, while the chips, differences in printer design and of course the fact that it's a bubblejet instead of a Piezo inkjet print-head design... Well, it all added up to one painful experience.
The symptoms experienced are those of printouts being banded with each pass somewhat faced and a distinct "gradient fill" effect that leaves the start of a printhead run being bold, and then fading more and more as it reaches the other side of the paper.
In the end I tried virtually every tactic I could think of and assumed, incorrectly that the problem was one of ink starvation, when in fact the exact opposite was true.. Turned out that the problem was one of ink overpressure, ie: the ink reservoirs I was using were too high in relation to the print-head thus forcing too much ink into the print-head and, at a guess, degrading the bubblejet process.
The solution is so simple I wanted to scream but basically you need to either raise the printer slightly (in my case around 2cm) or lower the ink reservoirs in relation to the printer. This corrects the imbalance of pressure and you will find that printouts appear in full colour without the banding/gradient effect.
Just to rub salt into the wound though someone pointed out recently that another CIS manufacturer already knew about this from back in the iP4000/iP3000 days... as per this link:
http://www.9to6.co.uk/phpbb2/viewtopic.php?t=77
#2: Author: Martin, Location: South Yorkshire, UKPosted: Sun Feb 24, 2008 3:02 pm — I need to add to this post as I've found that you can get overpressure issues if you overfill the cartridge too.
Ok, in a nutshell if you look at a brand new Canon OEM cartridge you will see that there is a sponged area and a tank segment full of ink. The sponged area has two distinct layers of sponge with the lower layer much denser and absorbant while the top layer is more coarse and holds very little ink. The important bit here is that there's no ink in the top portion of the sponged cartridge.
My mistakes (just discovered) has been to overfill the cartridges so that this top portion of the cartridge is full of ink and thus producing greater pressure over the printhead and creating the same issue discussed in the original thread posting.
The solution is pretty simple. If you overfill the sponged portion, drill a temporary hole above the sponged area and allow the excess ink to drip out until an equilibrium is reached with air above the sponged area and obviously ink in the tank (spongeless section). Obviously once you've balanced things out, reseal the hole you drilled and you're good to go.
Note:
It has been suggested that placing the tube fitting above the sponged portion creates too much pressure and that you should place your fitting above the spongeless/tank section. Unfortunately such an approach involves modification of the printer casing to allow fittings and tubing clearance in the printer and in some instances (MP500 for example) the case does not lend itself to any modification without a lot of potentially destructive work.
For myself I've found that so long as the cartridge has a balanced ink level as described above, it should work with the fitting over either section of the cartridge.
