white stripes on Canon MX700, replace print head or circuitry problem?

[ghwellsjr]

There is just the one purge pump but it has valves on it that can independently control the suction on the two purge pads. You have good understanding on all the other issues.

 

[inoe]

mission accomplished, and you sir, ghwellsjr, are the man!

the new printhead arrived this afternoon and, behold, the new nozzle check pattern:



I also snapped a comparison nozzle arrays on both old and new printheads,

old:


new:


not much to tell, the nozzle arrays on the old seems fine compared to the new one, apart from general wear and tear.

Nonetheless, here is my humble analysis of the problem.

Note on the color nozzle array (CMY) that there are 1 extra strips for each magenta and cyan. There are 5 strips on the CMY array (instead of 3, one for each color), with CMYMC arrangement. I suspect that each C and M strips are used for lighter shade of each, and to get a full saturation, the printer will fire up the secondary C and M strips respectively to get double density. I seems to remember years ago that the early professional grade 6 color inkjet have the light M and light C cartridge, and I suppose that is what canon try to simulate here with dual strips for C and M.

If you look at the nozzle check pattern on the original (first) post, the stripes are present on the darker shade of C, dark M, and Y, while the lighter C and M are fine. I think this corresponds to three out of five CMY nozzle strips failed to deliver, which can either be the nozzle overheated (running out of ink? i can't seem to recall any such incident) or circuity problem inside the print head that causes the module failed to energized the secondary nozzle strips for darker shade of C and M.

Either way, you are correct from the very beginning, that it is the print head that causing the problem. Rare occurrence, maybe, compared to the more common clogging and/or uneven delivery of ink, but I think I agree that any problem on the nozzle check, most likely the printhead is the culprit.

Thank you for your patience, ghwellsjr.

Regards,
inoe

 

[ghwellsjr]

You're very welcome. I love success stories.

You might be interested in this thread. It's actually for an older print head that includes photo black, but I think the principles still apply.