Question about Canon PIXMA MP780 All-In-One InkJet Printer

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PIXMA MP780 - not printing black chararcters

Hi - I loaded new cartridges 12mths ago and did not use. Today I set it up again only to find that when I print it will print the background graphics (in colour) nicely but will not print ant text? I then replaced the old black cartridges ((6 and 3e BK) and it made no difference.
I cannot print any black text?
Appreciate your help.
thanks Pieter

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  • 8 more comments 
  • sh1tty Jan 03, 2008

    What was the outcome here? Did you replace the item as mentioned in the reply?

    I replaced all cartridges in my MP780 (the 6Cyan, 6Magenta, 6Yellow and 6 Black) but the Black 3ek cartridge still reports as half full, so I didnt replace it.

    I cant print anything in black either. Color is perfect. Color text is perfect. Just black does not work. I even used Canon cartridges.

    Any clues?

  • Kobber Jan 04, 2008

    Our MP780 will not print at all. Other functions working. have replaced all the cartridges and also a new Print Head.

    Any suggestions?


  • Piet L Jan 06, 2008

    I was advised top soak the print head in turpentine for an hour and dry overnight.

    I can confirm if you do this it destroys the print head unit ie all the rubber rings dislodge and the solonoid/chip unit detaches also.

    My question is - it is worth replacing the printer head (and if yes, where can I buy it?) and if so will it work? Or is it a new boat anchor?

    regards, Pieter

  • Anonymous Feb 09, 2008

    I am having the same problem with my printer not printing black, this has been a great printer up to this point, we moved recently and I do not have the disc to reinstall. What can I do?

  • Chalupa Feb 14, 2008

    I have the same problem - suddenly no black. Cleaned heads, called canon tech support - they advised getting a new head - replaced head, same problem, it still does not print - WEAK

  • stuarts2 May 01, 2008

    Same problem here. My printer prints everything but black.

  • Anonymous May 04, 2008

    Same problem. Will not print in black. Colour is fine. Yorky

  • Anonymous Sep 09, 2008

    The cleaning and deep cleaning does not seem to be cleaning the nozzle I have to print on High to have even a light print. What do I do next?

  • swiv Jan 06, 2009

    Same problem. Everything but black. It fixed itself for one page after installing updated software. I am running a Mac.

  • jrstarwalker Mar 10, 2009

    PixmaMP780..working well last week ...this week I send e-mail ..person answers e-mail..what I wrote earlier prints... answer sent back to me by e-mail does not print...did maintenance....and it says auto head allinement failed...can someone help....tried to do manually but it still fails...thanks JR



7 Answers

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All the people in this forum with a Canon ink printer not printing black, especially if you tried replacing the print head and still have the same problem.

Your purge unit/capping assembly is most likely clogged. This can be caused by using crappy ink cartridges and by not using the printer for exptemely long periods of time.

You will have to disassemble the printer. First open the lid so the print head moves into the centre of travel. Unplug the power cord. Remove the upper case (can be hard to do, usually they're snap-together).

Remove one screw on either side of the print engine and remove the engine from the lower case. Unplug the cables that go from the main board to the purge unit (the large black assembly covered with old ink, located on the right side of the printer where the head usually would stop after you've finished using the printer and shut it off).

Now you have to remove that black purge unit from the right side of the engine. Usually there are two screws holding it in place.

Give the unit a bath, carefully removing old ink from everything so the unit looks like new. (be sure to remove the one motor first or you will ruin the motor). Check the bottom and make sure the two small clear rubber tubes are not clogged with old ink. Clean the absorber off (the pad in the lower case) if it has ink piled into a small hill shape.

If the tubes look like they might be clogged, you'll have to find a way to clear them out. I can do it in my shop, but it's too in depth to explain.

Reassemble the printer, connect to a PC and do a few deep cleans and print out a test page. Problem solved.

Remember, if one colour is not working it's because the head is clogged. You will have to do multiple cleans to get it to work. If it still doesn't work, then either it's REALLY clogged or the purge unit is not working because it's clogged. If you buy a new print head, then the only thing left is the purge unit. Be brave and try the disassembly and cleaning, or take it to your local service shop.

We charge $45 CDN for a job like this.

Rule of thumb: If you can get it fixed at a shop for 1/2 prince of a new unit, go for it.

Posted on Dec 10, 2008

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My PIXMA MP780 stopped printing black for documents. Running the printer's cleaning routines would not fix the problem. Since only one color was not printing, it was likely, according to others here, a problem with the printer head.

Rather than buy a new printer head, I decided to try to clean it. Following the advice of others, I removed the head and soaked it in very warm water for a couple of hours. Ink came out both sides of the black ink section, with strings of black ink coming out of the text black nozzle (the longer slot on the bottom of the printer head off by itself to one side). I changed the water frequently, and when changing the water ran water directly into the intake (the round, screen covered oriface that mates with the round hole on the bottom of the ink cartridge). Once no more ink was escaping out of either the nozzle or the intake hole, I patted down the printer head and left it overnight to dry.

The next morning, I put the head and ink cartridges back in and ran a test print. The black text ink worked marginally at first, but then after several deep cleanings, stopped printing again. However, rather than smash the head with a hammer, I decided to try one of the other solvents recommended - isopropyl alcohol. I pulled the printer head again, swabbed the black ink nozzle using a Q-tip dipped in isopropyl alcohol, and then poured isopropyl alcohol into the section of the top of the head where the black text ink cartridge seats, pouring in enough that it came over the top of the screened intake hole, but not so much that it overflowed into other sections for the other colors of ink (although perhaps I should have to clean them as well).

After 20 minutes or so of soaking, I poured out the isopropyl alcohol, patted the printer head dry, and then reinstalled the printer head and the ink cartridges. Bingo. The black text ink printed an almost perfect test print which, after a couple of deep clean cycles, became perfect test prints. Not only that, but my color photo prints now look better than they have for a long time.

It is unclear to me whether the water soak was really necessary, but it did have the advantage of fully cleaning out the head, and there was a lot of dried or viscuous black ink inside it. One warning from others was that certain solvents may damage gaskets and other plastic parts. Isopropyl alcohol is a pretty useless solvent when it comes to removing glues and the like so I wasn't extremely worried, and it didn't seem to have any negative effect on my printer head, but it is possible that the damage will show up over time and for me it has only been a day.

Posted on Mar 09, 2009

  • oorbak Jun 15, 2011

    I had the same problem with my PM780 after not having used it for a few months. Color ok. but Black missing at certain intervals down a page, "on and off".
    My solution was similar to swiv's but I only used ink to rinse the head. No water, no alcohol. Just printed a few pages, removed the ink carts, made sure the ink.cart's padding was soaked in ink, reinserted, printed another couple of pages. The ink gradually got better & better. Now - all ok!


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Hi - I had the same problem. Randomly, in the middle of printing a long document, black just wasn't appearing. I went online and tried all the regular procedures...(head alignment -which gave me an error- cleaning, deep cleaning, MULTIPLE deep cleaning) Nothing worked.

I'm not a very tech savy person but after some research I discovered that it was an issue with the print head. Many people just got tech support to send and install them a new one but because I'm poor and impatient, I tried cleaning/fixing it myself.

To remove the print head you remove all the cartridges, lift up the grey lever and shimmy the black casing out. This is the print head. Be careful, its full of ink and there's a circuit board on the back you don't wanna mess with. Fingerprints can cause the circuits to malfunction.

I used about 40 Qtips with windex along the bottom shiny plate AND inside where the black 3e was placed. Your hand will probably be black at the end. But worth it!

Let the print head dry and then return to printer along with the catridges. Perform a deep cleaning to remove an windex traces. Print a "nozzle check" from the printer's maintenance tab and voila! My 3e checker pattern was back! Hope this helped some of you.

- Nancy

Posted on Feb 01, 2009

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I have had this problem on 2 of these printers. With much patience, I have been able to solve it by repeated cleanings including print head alignment, followed by turning off the maching for an extended period of time (preferrably a couple of hours), then cleaning again. After repeating this process, I finally got the black to partially print, then repeated the process again and it finally worked!!! Hooray!!!

Posted on Apr 27, 2008

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Hi All,

just my 2 penneth worth-

Problem- can't photocopy black-turns out green, had problem for 3 months.
( can print black from machine , colour OK too)
Lots of friends have had problems with different 3-in-1 devices

Solution- copy mode was 'photo'-changed to plain-hey presto,all OK
(copy mode was in 'photo' as I was copying pictures)

Hope this works for someone

Posted on May 28, 2009

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About a month ago my Pixma MP780 suddenly stopped printing the 3e black as well. Did some research & wound up calling Canon tech support. They advised me that there was an 80% chance that the problem would be fixed by buying a new $50 print head. Against my better judgement, I purchased & installed it. (I liked the printer & am biding my time for color laser multifunctions to come down)

To make a long story short - if your problem ocurrs from one day to the next - it is not likely to be caused by bad ink, "non OEM ink" or clogged heads etc.

I think the black head driver IC is shot - seems to be a very common problem - just like canon's E18 error - which I was burnt by as well.

So I'm looking at the MF8180C

Anyone want to buy a almost new print head ?????

Posted on Feb 06, 2008

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Print head is a user replaceable part like inks, clicks out replace it.
PIXMA MP780 - not printing black chararcters - ca5929e.jpg INFO link

Posted on Jan 02, 2008

  • 5 more comments 
  • Soulvisitor
    Soulvisitor Jan 06, 2008

    Comment by Kobber, posted on Jan 04, 2008
    Our MP780 will not print at all. Other functions working. have replaced all the cartridges and also a new Print Head.

    Any suggestions?

    Clean print head connections, must run a few cleans to prime new head!!

  • Soulvisitor
    Soulvisitor Jan 06, 2008

    After Installing your Printhead
    You may need to perform a head cleaning routine after installation and the print head will need to be re-aligned, refer to your user manual on how to do this

    Read instructions, use only real canon ink to prime it!

  • Soulvisitor
    Soulvisitor Jan 06, 2008

    No it is probally not worth repairing any inkjet printer it is more economical to buy new with warrenty and new consumables

  • Soulvisitor
    Soulvisitor Jan 06, 2008

    Whats with rating Pieter

    You didn't even buy a new head as I suggested

    You followed not my advice in along shot but you rate me (who is helping you) for your mistake. Peolpe just love to vent their own frustrations at others.

    Cheers Mate!

  • Soulvisitor
    Soulvisitor Jan 06, 2008

    Link to purchase head

  • Soulvisitor
    Soulvisitor Jan 07, 2008


  • Soulvisitor
    Soulvisitor Jan 08, 2008

    I just finished fixing another of these that makes about 20 in all.

    This customers complaint, can't do head alignment, the reason couldn't print with 6BK.

    All I did once again was replace the two non genuine inks the customer had installed with the proper canon item, tested it, made no difference cause crap ink had blocked head, so then a new canon print head was put in, ran an alignment, picture perfect!

    Customer was advised not to give printer any more injections

    Fix is Replace any non Canon or old inks, test, if auto head alignment still fails, then buy a new head and fit it, run a alignment, if it fails run a couple of cleans, try alignment again, if it fails, clean contacts, test.

    My bet is everyone of the posters here have not in fact replaced ink with Canon product, they have changed crappy ink with crappy ink that they get cheap or have not replaced head at all.

    I just cant see any other possibility except maybe if you have been using crap ink, it has leaked and damaged head contacts.

    P.S. I am not a employee of canon, just telling what is seen in a printers workshop, all brands of machines end up stuffed cause of inferior products fed to them. Wake up recyclers you are filling the world with wrecked machines.


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