Banding On Pixma Mp750

[Jimmbo]

Even though I've aligned, cleaned and deep cleaned, nozzle check shows this strange banding on the 3M printhead:
(click here to see image)


Here's how it affects color printouts:
(click here to see image)

The rainbow's colors should be solid, of course.

Help! And thanks!

 

[The Hat]

Your print head has been damaged beyond repair so no matter what you do with it now it won’t make any difference. (Electrical problem)

Now I know you didn’t want to hear that starting off but you efforts to resolve your poor print quality probably only made matters worse.

When you first see signs of poor output you should stop printing immediately and try to get to the bottom of your problem straight away, but you should only do nozzle prints nothing else.

You can run a normal head clean after a nozzle check and if that doesn’t resolve the issue for you then concentrate on your cartridges because that’s usually where most poor print issues start from, sorry for the bad news..

 

[Jimmbo]

Thanks for the reply!

I'm not clear on something. My understanding was that Nozzle Check is purely a diagnostic step, and it doesn't actually change/fix/adjust anything on the printer's end.

Was I wrong on that? If not, then I don't understand your reply, above.

 

[The Hat]

You are 100% correct, it is indeed only for diagnostic purposes, but it was the other things that you’re doing like aligning the print head deep cleaning and printing multicoloured test sheets that can be destructive.

When you get a faulty nozzle print check that is telling you that there is something wrong and to corrected it before proceeding with any further print jobs.

The fact that the nozzle print check is only for diagnostic purposes makes it an ideal non destructive tool for trouble shooting print problems because it doesn’t harm your print head..

 

[Jimmbo]

So you said "you should only do nozzle prints nothing else."

Since nozzle print doesn't actually help anything, i'm sort of confused by that instruction. What was the thing to have done then?

 

[stratman]

Your print head appears to be bad and you need to replace it. Why the malfunction occurred is anyone's guess. Sometimes they just go bad. You can try cleaning the electrical contacts on the print head with a lint-free cloth and isopropyl alcohol or use a soft pencil eraser. It is possible this is a logic board assay failure, which are supposed to have an error code displayed, but the odds are greatly that this is an irreparable print head malfunction based on your description and images.

Once a problem with printing is found, nozzle checks are recommended as the only printing to be done as a diagnostic to follow progress of clearing the problem in order to prevent further widening of the problem such as due to lack of ink flow which can kill a Canon print head in the first place. Ink acts as a lubricant and insulator in a Canon print head which uses heat to spray ink onto paper. No ink means heat can destroy nozzles. Printing just nozzle checks reduces the risk of further damage versus printing images or other things you might usually be printing otherwise and is considered safe by the Forum.

 

[turbguy]

Nozzle check prints are an easy way of obtaining a lot of information on printer performance while maintaining a very low level of use or "duty" on the print head. An even better test is to force a service test print, which can be a bunch of convoluted button-presses on your printer.

The lower the duty on the print head, the less likely of doing [more] damage.

That said, you can try printing on a high quality output (change paper settings in the driver) to try to force the print in one direction only...that "might" help with the banding.

And agree, your print head is probably damaged.

 

[PeterBJ]

Hi Jimmbo

Your uploaded pictures are typical for an electronic print head failure. If cleaning the contacts brings no improvement, only a new print head might help. But there is a risk that the defective print head has damaged the logic board, and a damaged logic board can damage a new print head. If the print head was not cleaned outside the printer using water, Windex, and similar, chances are good that the logic board was not damaged, and that a new print head will restore the printer to good working order.

The parts number of the print head is QY6-0049-000. You can use this or just qy6-0049 as Google search term to try to locate a new print head. But Canon has stopped producing these print heads, so it might be difficult to locate one.

As mentioned by stratman Canon print heads can fail for no apparent reason especially if old, and your printer may be close to ten years old, so I think you have done nothing wrong.