MP780 No Red, Yellow or Green Colors

[SCGUY99]

My Canon Pixma MP780 would not print in pigment black (BCi-3ebk) or yellow (BCI-6Y) a few days ago. After several cleanings, extended nozzle checks, a cleaning of the purge unit and a rinsing and overnight soaking in Windex of the printhead, I was able to get the printer to print in black (3ebk) again but not yellow. I spent a lot of time reading many detailed and helpful postings on this forum about getting the ink to flow again and I remember one of them said something to the effect of when the printhead is being cleaned/drained to watch if liquid tries to come to the top of the ink heads on each of the colors. Well, liquid never rose above the mesh screen on the yellow ink head and now the printer will not prink in red, yellow or green. If I print an image of a red, green or yellow car, they all come out blue. Any suggestions on what I might try next?

 

[ghwellsjr]

If you take a paper towel soaked in Windex or just plain water, and you drip a few drops of Windex on to each screen, then you should see bubbles or other action on each of the screens as you blot the print head on the wet paper towel. If you don't, then you probably have an ink clog somewhere in the print head. If you do and the print head still won't print in that color, then you probably have an unfixable electrical problem in the print head and will probably need a new print head.

 

[SCGUY99]

Thanks for the tip. I cleaned the print head again with Windex and that fixed the problem. I guess it needed a very deep cleaning.

 

[l_d_allan]

a cleaning of the purge unit

I'm curious how you did that. I'm aware of how to check if the purge unit is working , but not how to clean it (or whether it even can be cleaned).