Canon MP630 magenta printing only on one half of printhead

[Genesys]

When I currently print with my Canon MP630, color images all look green-blueish with a small horizontal stripe of correct coloration about every cm.

When printing the nozzle test page, I see that the darker magenta stripe is only half it's width, indicating that magenta does not print there. interestingly the brighter magenta stripes print completely (see attached photo).

I already throughly flushed the printhead with 20%/80% alcohol/distilled water several times and ran several cycles of the intense printhead cleaning program, without improvement.

Since the lighter magenta stripes print completely, there might something else be off.

Any idea what could be going on and how to fix it?

 

[Ink stained Fingers]

The missing half magenta patch is an electrical fault within a chip in the printhead, a range of nozzles are not addressed anymore. It is not recommended to do much anymore with such printhead since the failure may propagate and damage more, in the printhead and ulitmately on the motherboard. There is no way to to determine the possible residual life of such printhead e.g. just to print text with the black ink channel.

 

[Genesys]

Thank you for your reply! So this chip resides inside the printhead and replacing it would likely fix the problem? How come the lighter shades of magenta are printed on the testsheet, do these use different nozzles?

 

[stratman]

The missing magenta is an electrical fault, either in the print head or the logic assay board, and is irreparable. If the malfunction is in the print head then a new print head will resolve the issue. If the malfunction is in the logic assay board in the printer then a new logic assay board is the answer. We cannot know which is affected but the likelihood is the print head.

There is also the rare issue of a print head problem causing irreparable damage to the logic assay board and vice versa. For example, a logic assay board malfunction and then irreparably harm the print head. A new print head may also be harmed as well.

As I said, the most likely scenario is a new print head will resolve the issue BUT we cannot be 100% sure. You take your chances.

How come the lighter shades of magenta are printed on the testsheet

Nature abhors a straight line. It is unlikely a clog of ink perfectly blocks out half of the Magenta. That the other tests of Magenta appear good most likely is due to a different software /code subroutine executed than the one where the missing Magenta happens.

Since you have little to lose at this point, you could flush with water, then soak it in liquid dish washing soap like Dawn or Fairy for 12-24 hours, flush the print head with water, dry so that no residual water remains to short out electrical contacts and circuit boards, and give it a try again.

ran several cycles of the intense printhead cleaning program, without improvement.

Deep cleaning cycles are to be done once or twice in a 24 hour period or risk destruction of the print head.

 

[Ink stained Fingers]

Canon, the bubble inkjet method, needs separate nozzle rows for different droplet sizes, Epson can modulate the same piezo nozzle to emit droplets with different volumes. There is a chip in the printhead soldered directly onto a flex cable, a chip without case encapsulated after mounting, and this chip is not available as an individual spare part. I remember a few reports that people have tried to move such a chip from one printhead to another but without success, the surface mounting is too complicated as a manual process since the lead spacing is extremely small, and getting the chip off in the first place was another challenge. It may now look slightly different inside printheads of different generations but it is def. not repairable at this location. You may look for another printhead or consider replacing your printer soon.

 

[The Hat]

Any idea what could be going on and how to fix it?

@Genesys, your nozzle print suggests that your print head has a partial electrical burn out on the magenta nozzles and your only solution is to buy a new printer, because print heads are not available for that model any longer, you can however go on using it for black text, sorry...

 

[stratman]

your print head has a partial electrical burn out on the magenta nozzles

Then why are the lighter Magenta nozzle check swaths not missing that portion as well?

The issue would then not be the nozzles themselves but instead a malfunction in the firing of the nozzles.

 

[PeterBJ]

For cyan and magenta the QY6-0072 print head used in the MP630 and other printers has got 3 nozzle sets , normal, medium and light. See this extended nozzle check from the MP630 service manual:

 

[The Hat]

Then why are the lighter Magenta nozzle check swaths not missing that portion as well?

Because they’re not burned out, only the full magenta nozzles are affected.
click to enlarge

 

[stratman]

3 nozzle sets , normal, medium and light

3 different nozzle sets or 3 different recruitment strategies of all nozzles available? In other words, the darkest Magenta swath uses more or all the nozzles, the lightest color swath uses fewest of all the nozzles giving the perception of a lighter shade (less ink laid down).

If there are 3 different nozzle sets - without any nozzle used in one set used by another set - then droplet size or number of passes may explain the different shades.

The conclusions I've drawn from the seminal thread on this subject by ghwellsjr at

https://www.printerknowledge.com/threads/anatomy-of-a-canon-print-head.6190/

• there are multiple sets of nozzles for Magenta
  
• either within the same set are same sized nozzles OR within the same set are different sized nozzles for different sized droplets
• in posts #14-17, the simulated effect of burned out nozzles by placing tape over one set of Magenta (and Cyan) nozzles resulted in a decrease intensity (or lighter shade) of Magenta (and Cyan) but NOT a complete loss of ink.
• post #19 demonstrates that the darker swath of Magenta uses more total ink drops and also uses different sized ink drops - there is potential recruitment of various nozzle sets, not just only 1 of the 3 sets for the darkest Magenta swath. The tape occluding a set of nozzles does not result in a complete loss of ink. Some ink from other Magenta nozzles sets still spit out ink.
• finally, in post #44, @turbguy postulates:

  Actually, I suspect that the majority of print head failures (the ones that have obvious missing patterns during nozzle checks) are due to failures not in the nozzles, BUT IN THE MUTIPLEXING SCHEME ELECTRONICS embedded in the head circuits.

This is what I was referring to, albeit not as well or nearly as accurately, about how one half of the dark Magenta swath could be missing while the other lighter swaths remains complete. It isn't the nozzles but something else upstream from the nozzles that can carve out such a specific and well defined malfunction.

I also wonder if this occurs suddenly as well, unlike maybe the slowly progressing lightening of color as more nozzles fail until a blank stripe is noticed after enough of nozzles are burned.