R2400 / ink occasionally leaks puddles onto prints

[alsetn]

Once in a while during printing large blotches will streak across then print. Sometimes but not always this will occur after topping up the cartridge. As I assume is correct, I am leaving the chip-end vent open and the opposite end plugged, with usually excellent printing quality.
Is there a pressure/vacuum issue that changes after unplugging to fill?

here is an example:
http://proto.dangyro.com/blotch.jpg

 

[mikling]

The internal pressure is supposed to be slightly negative under normal operating conditions. Once you open the plug, the pressure becomes neutral since the negative pressure is lost. When filling the cartridge, the ink in the cartridges then makes the pressure at the nozzle slightly positiive as the ink level is raised. If you are able to fill and replug the cartridge quick enough, the slight positive pressure will not have caused ink to leak out of the nozzle and cling to the underside of the printhead. Now if ink did in fact leak out a bit and cling to the underside, then puddling would occur and these could drop off while printing...and you get what was shown.
Also once the printhead goes through the motions, the cartridge is supposed to then become slightly negative again since ink is removed and air enters the cartridge at the bottom. This slight negative pressure prevents the ink from leaking out afterwards. generally after a clean, these issues disappear or after some use, the underside loses the ink and the pressure is set up properly again. The best thing is to sacrifice a sheet of copy paper with some printing before putting a sheet of the good stuff.
Now and then you also get a blowoff check valve inside the cartridge that is stuck open and the cartridge will not keep negative pressure this will also cause the drips. To fix this situation, you reseal the cartridge and use the syringe to generate a negative pressure and this will reseat the check valve. Sometimes a head clean operation will reseat the valve. This valve is at the top and is hard to see and is there as a blowoff valve to vent positive pressure in the cartridge from the expansion of air internally which would have forced ink out of the nozzle.
There's quite a few engineering details in these refillable cartridges actually.

 

[OutOFtheinkwell]

Yes, I occasionally see this on my Epson 1400. I usually let it go as it only does it once, or I print with cheap more porous paper to act as a blotter, or I power the printer off and on so the rubber wiper is brought into play. Either way it isn't a major problem. Recently my wife kept printing until 2 dampers ran dry and that caused problems for awhile. I was getting a bright( red or green) horizontal thin line down one side of the paper for a time. It finally worked itself out and all is well for now. I do think the Epson models with the Piezo heads instead of the thermal heads are more durable and forgiving of these things. As I type this my wife is happily printing away and things look good.(subject to change without notice) LOL! I think she is more careful now and she just told me to check the ink level which I need to go do now! Outoftheinkwell !

 

[OutOFtheinkwell]

Update on the last comment. The dampers still look good the lowest being the LM and it is over half full! As most of you know the lite colors, ( LM and LC) almost always are used up at about a 2 to 1 ratio. Sometimes I just top off these two colors and print some more! Outoftheinkwell)

 

[Fenrir Enterprises]

The new style dampers I have for my 1400 are gravity feed with no valve at all. So far they're working okay but I do wonder about the pressure issue, since it's going to be all over the place, neutral when you open it and fill it, gradually becoming negative as the fill port is sealed and ink is being pulled by the printer. Hmm.

 

[Lothman]

On my R2400 I had similar print results. The reason were not the refillable cartridges but a clogged tubing to the waste ink tank. So the ink stood on the pads instead of beeing pumped off. Then the Printhead was wetted by the small ink sea on the pad and dropped that on the paper.

Just have a look on the inkpad on the rest position while printing. When you can see the ink standing there (instead of the foam structure of the pad) it has nothing to do with the cartridge.

 

[alsetn]

Solved! (workaround)-
It seems the temporary loss of vacuum after filling is the culprit. As suggested I just have to do a "clearing" print and let the vacuum build up again.
The following prints are fine.

Thanks all.