iP7250 Head miss-aligned PGBK only

[LesD]

(I'm not sure if this is related to changing the PGBK cartridge.  After the change we noticed this issue, but as this printer is not used that often it could be unrelated.  I put back the old cartridge and still have the same problem.)

This is only a problem with the PGBK head.  The BK and others are fine.  When printing black I am seeing each letter double - all verticals are printed twice, offset by what looks like just under half a mm.  With 8pt character this can be seen clearly.  With larger point sizes the verticals come out thick (overlap).

This problem is not on every line.  Some lines come out perfect while other are perfectly wrong - the whole line is either OK or all characters are wrong.  Printing several lines shows no specific pattern as to which line is OK or not.

Printing a test pattern (the rectangular grid) shows the top and bottom two rows as OK but all verticals in the remainder rows are printed as two lines tapering from zero to a gap of about 0.5 mm.

(I also noticed that the test pattern horizontal lines are not perfectly parallel to the paper's edge - though this my be by design)

I have run automatic and manual head alignments, regular clean and deep-clean but nothing helps.

Any suggestions welcome.

[Tiffany]

Welcome to The Canon Forums!

We appreciate your participation, though we need to let you know that your product appears to be a model that is not supported by our team here at Canon USA.  While the commmunity is welcome to chime in, the Canon Community Forum is hosted and moderated within the United States by Canon USA. We are only able to provide support for Canon products manufactured for and used within the US market.

If you live outside the United States, please click HERE and select your country to find support in your part of the world.

Feel free to discuss Canon products sold outside of the United States, but please be aware that you will not receive support directly from Canon USA

[shadowsports]

@LesD,

Have you inspected the encoder timing strip?

While we aren't there to see the problem, a dirty timing strip might cause ghosting or random printing alighnment issues.

Use this for reference:

Canon Knowledge Base - Cleaning the Encoder (Timing) Strip - iP8720 / iX6820  

[LesD]

Thanks but I did actually find reference to that earlier and cleaned it (not so easy to do) but it made no difference.

I would expect such an issue to disrupt the workings of all heads rather than this specific one - though there is an element of randomness in that not every printed line is faulty.

Thanks again for the suggestion.