Unresolvable banding on Canon ipf 6300

[Danny Burk]

Hello all....I'm having unresolvable banding on my 6300, and I hope someone may have an idea that I've not already tried. Long story, but here goes...

The printer started banding in November 2012; it turned out to be a failed R printhead and replacing it solved the problem. I bought a spare head shortly afterward, assuming that the L head may soon need replacement. Move forward to a month ago, and the problem began again. Banding started out of the blue one day, with no changes to setup, paper, custom profiles, etc. that have worked fine for hundreds of prints. All drivers, etc. are current versions.

Banding is horizonal (direction of print heads) and shows up on b&w prints; I can only see it in areas of little detail that are quite dark, about quarter-tone (i.e. dark areas of open sky). I've tried color gradation tests and can't definitely see banding there, although it's possible that there is a nearly undetectable amount on certain colors (it's so minor, if there, that I can't be sure), but very obvious on those particular areas of b&w prints, on drum scans of b&w negs and on grey gradation scales that I've created in PS.

I have spoken to Canon support 4 times for a total of about 6 hours. I've done multiple A-B cleanings; nozzle check is always perfect. I've done auto head adjustment, auto and manual band adjustment; no better. Tried printing through the PS print function (I normally use the Canon plugin), and have tried a variety of my usual papers (both gloss and matte) and quality settings. Max number of passes helps, but it's still visible, along with a pronounced yellow shift.

Canon replaced the R head in warranty a few weeks ago; no help. They had me replace the L head next (my cost, using the spare I bought last year) last week; again, no difference.

Have there been any reports of air in lines in these printers, or defective ink? Is there a way to force the printer to print only one of the 12 colors at a time, other than nozzle check?

At the moment, it seems to be an unfixable problem...am I missing something else that I could try?

Thanks for any suggestions! 

[aaronchan]

are you printing your image in highest resolution?
if yes (even no), try to print it in different resolution.
I've have similar problem before but solved in this solution.

aaron

[Danny Burk]

Thanks for your reply. Yes, one of the Canon techs asked me to print at a different res (I normally use highest). There was an improvement using "Max No of Passes", but slight banding was still present.

[aaronchan]

instead of increasing (max no. of pass), try to use something like high rather than highest.

aaron

[Danny Burk]

He had me try that too, thanks.

[Roscolo]

Is it happening on all papers or just some papers?

[Danny Burk]

All papers, glossy and matte.

[Roscolo]

Did you let it do an Advanced Head Adjustment? May not be related. I didn't have banding, but I had a recurrent line I couldn't explain. Can't remember the exact menu item on the printer (my printer is turned off right now) but it was something like Advanced Head Adjustment. Took about 20-30 minutes and printed about a 4 foot long chart while it did it. Solved my problem, which may not be related to yours. Before that I had tried adjusting vacuum strength to strongest. The head adjustment is what worked.

[Pete Berry]

Danny, I'd bet a nickle or two that the problem is in a head contact(s) or, more likely in the ribbon cable to the heads. This has come up several times in the Canon LFP Wiki in the past 6 months or so with print problems not cured by head or cart replacement, as well as other electronic components, but did with cable replacement - apparently not a simple task, though. You didn't report any head error messages which generally go along with, or precede head failure.

Pete

[Richard.Wills]

We've had banding show up on our 8300, where the nozzle checks initially appeared fine. When scanned, and then inverted in PS, we could see nozzles being deflected. This was enough for our dealer to send us replacement heads. Photoshop made it much easier to see, than looking over all the light coloured colour bars of a nozzle check, with an 8x loupe.