Weird iPF8400 printhead issue

[TheMatrix]

Hello,

Let me start this by saying I have been using iPF printers since 2007. I have seen all sorts of failures, and this one is baffling to me...

I'm having the weirdest problem with my 8400. It was sitting for a long while, and I had to replace both printheads last year. Initially both worked fine, but then every so often the gloss black (BK) channel would get all wonky. I rarely print on gloss, so it wasn't an issue. I have only used genuine Canon ink and printheads (no knock-offs from Amazon).

Symptoms: The nozzle check for 11/12 colors is always perfect. It is only BK that is the problem. Every nozzle check shows a different sputtering pattern, and every so often both squares will be perfect. That sounds like a clog. Now here's the thing that is puzzling me - on a letter-sized test print, after the first few dozen passes, the banding stops and it starts to print normally. This makes no sense, as any sort of ink starvation issue would be getting WORSE with each pass, not better. Also, any stubborn physical obstruction (pet hair, dust, etc) would simply never go away - it wouldn't magically disappear after ~6" of printing every time. I don't understand what the issue could be.

Does anyone have any suggestions? I was thinking of trying that "Magic Bullet" printhead cleaning liquid, but I can't seem to find it anywhere in the US. I see lots of "printhead cleaning fluid" on Amazon though. Is it the same?

Thank you!

[TheMatrix]

Not sure why the nozzle pattern image didn't upload, but here are 3 of them side-by-side.

[Czornyj]

Hello,

Let me start this by saying I have been using iPF printers since 2007. I have seen all sorts of failures, and this one is baffling to me...

I'm having the weirdest problem with my 8400. It was sitting for a long while, and I had to replace both printheads last year. Initially both worked fine, but then every so often the gloss black (BK) channel would get all wonky. I rarely print on gloss, so it wasn't an issue. I have only used genuine Canon ink and printheads (no knock-offs from Amazon).

Symptoms: The nozzle check for 11/12 colors is always perfect. It is only BK that is the problem. Every nozzle check shows a different sputtering pattern, and every so often both squares will be perfect. That sounds like a clog. Now here's the thing that is puzzling me - on a letter-sized test print, after the first few dozen passes, the banding stops and it starts to print normally. This makes no sense, as any sort of ink starvation issue would be getting WORSE with each pass, not better. Also, any stubborn physical obstruction (pet hair, dust, etc) would simply never go away - it wouldn't magically disappear after ~6" of printing every time. I don't understand what the issue could be.

Does anyone have any suggestions? I was thinking of trying that "Magic Bullet" printhead cleaning liquid, but I can't seem to find it anywhere in the US. I see lots of "printhead cleaning fluid" on Amazon though. Is it the same?

Thank you!

Print head cleaning fluids are usually for piezoelectric print heads, and as such may not work or even damage the print head. Furthermore, it will be difficult/impossible to get rid of it from retention tank without wasting all ink from other retention tanks, so it's actually a very bad idea.

[Lessbones]

I've been using the ink owl flush/cleaning solution on my canon heads for years with no issues.  What this looks like to me, and especially given it going away with printing more, is that your capping station may not be making a good seal on that part of the head.  The capping station has a number of rubber seals on it, and these can degrade over time, or get bent out of shape in some edge cases.

Generally print head cleanings come in two forms:

1.  Fire the nozzles a bit into a flushing pad, then wipe the nozzle plate clean of excess ink
2.  Create a seal between the head and the cap, and build up suction to draw ink through the heads WITHOUT firing the nozzles.

2 is more commonly performed as a "power cleaning", but it is also generally part of a regular cleaning routine too, and if your cap isn't making a proper seal, it can actually cause the ink to be drawn backwards into the head like what you're seeing there.

I would first inspect the capping station in service mode "CR REG Unlock" and at the same time i would pop the head out and check for any dried ink on the bottom, especially around the area where the rubber seal makes contact.  Removing the head in service mode when unlocked won't trigger a massive flushing of ink like it would normally when doing a "replace head" procedure.

If none of this is conclusive, I've also had ink lines develop little holes through friction with the underside of the top of the printer since the plastic parts to hold them down have snapped off my head carriage-- If the holes aren't too large you wouldn't see ink leaking, but you'd see bubbles getting drawin into the line which could also cause issues like this.

[Kyle Jackson]

Hi, if this were an HP I'd say it's got air in the heads and/or ink lines. Based on @Lessbones description of the Canon's head priming system, it's pretty much the same concept that the HP DesignJets use: a capping station with a suction pump for purging/priming. But over time the heads can get air in them -- meaning they're low on ink -- and you get this pattern of faded/banded printing at the leading edge of a print, which sometimes improves as the print progresses.

In HP-land we can tackle this first by weighing the heads to see if they have air in them, since we know how much a brand new / fully primed head weighs. If the heads are light it means air. Options are replace the head (no longer possible for discontinued HP heads), or use a purge / priming kit to draw air from the heads and re-prime them with ink. The same kit can also be used to draw air bubbles from the ink tubes leading to the printhead carriage. Finally like @Lessbones mentioned, a good cleanup of the capping / service station area, and the printheads and carriage, to get rid of any crud that might interfere with normal operation. This can restore normal printing quality, provided the heads still have enough functional / unblocked nozzles. If not, the nozzles could be soaked or a cleaning fluid could be used with the air purge kit. (I've not yet used the fluid tho, maybe some day...)

[TheMatrix]

use a purge / priming kit to draw air from the heads and re-prime them with ink. The same kit can also be used to draw air bubbles from the ink tubes leading to the printhead carriage. Finally like @Lessbones mentioned, a good cleanup of the capping / service station area, and the printheads and carriage, to get rid of any crud that might interfere with normal operation. This can restore normal printing quality, provided the heads still have enough functional / unblocked nozzles. If not, the nozzles could be soaked or a cleaning fluid could be used with the air purge kit. (I've not yet used the fluid tho, maybe some day...)

Thanks for the replies, everyone. I took the side panel off and cleaned the cleaning unit, but it looked ok. The rectangular seals that go around the heads look fine too. I inspected the head but I didn't see any residue or debris that could be causing this. Does anyone know where to find a purge kit? I see a few on amazon, but I don't know if I should trust them. This site (https://www.marruttusa.com/printer-maintenance/inkjet-cleaning-videos-canon-ipf.php) shows a syringe being used to push fluid into the chamber, which looks like it should help purge any air, but unfortunately I don't see a way to purchase that Magic Bullet stuff. Hence why I'm looking on amazon...

[TheMatrix]

I flushed the black channel with isopropyl alcohol, then distilled water using a syringe. The nozzle check was faded gray (as expected with watered down ink/water being ejected) but otherwise almost perfect, and I was very happy. Then as the black ink eventually refilled the chamber over the course of many black test prints and a few head cleanings, all the problems came back. I think the problem is the ink itself. I have no idea how to proceed at this point. :/ The ink expired years ago, but I have never had a problem with old ink in any iPF printer, and all the other 11 colors are working fine. Has anyone encountered this before?

[Kyle Jackson]

That syringe looks the same as the one we use for HP printheads. It's just a big blunt plastic tip. If the tip is same size then maybe an HP head syringe could be used if unable to get a Canon one.

It's aqueous pigment inks and the pigment particles can't dissolve in water, so we're just using water to "re-hydrate" any dried pigment clogs to soften them and help flush them from the nozzles. HP docs stress about never touching the nozzle surfaces or using alcohol, but it seems using at least distilled water is okay for soaking and blotting onto lint-free wipes, and there are some vendors that sell a "cleaning solution" (no idea what's in it). The Canon info you linked seems similar.

That link suggests taking everything out of the head so there is nothing in them but air    That would be death for HP heads -- we want the opposite, to get air out of the heads and ensure they're re-filled with ink. Maybe the Canon iPF head priming system is different and removes the air effectively all on its own? Like do Canon heads contain any ink in them when new in the package? The HP heads do, and the printer purges air too but it seems some gets "trapped" inside heads the longer they're in service, so sometimes a manual air purge and re-prime with ink keeps them going. (HP's design approach went with "cheap" disposable heads, so we're really expected to just toss them and replaced with new ones.)