MP760 giving intermittent print head error message, faulty test print

[warwickt]

Hi all, I'm new to this forum which I found about 2 weeks ago when my PIXMA MP760 began to have problems.

A short history: Purchased new in October 2005, still has original printhead, very light use (approx. 450 copies), typically one or two uses per week. Two weeks ago, an "incorrect print head, replace with the correct print head" error message suddenly appeared, the alarm light flashed and printer became completely unresponsive. I tried removing all tanks, reseating the print head, cleaning the print head using (a) water and (b) a Windex-equivalent -- no success. I switched the printer off and left it for a day or two -- when I switched back on, it worked! Test print good, images printed as expected. After about 2 hours, suddenly the "incorrect print head" message reappeared, printer again completely unresponsive. Turned off, left for a few hours, turned on, same error message. Switched off and left for another day, switched back on, working again! (I am not making this up.) After a few hours, died again. Left for another day or two, working again! Right now it's working. But in a few hours I'm guessing it won't be.

I don't understand intermittent faults like this: what can cause error messages to appear one day, then disappear the next with no intervention in between? Baffled.

A further possible clue (but may be unrelated): The test print has been progressively deteriorating over the same period. I have run the cleaning utility repeatedly, including deep cleaning, but it has not made any difference. All tanks have ink. Right now the test print looks like:

i.e. three errors: (1) the top '6C' band is divided into two cyan stripes; (2) the 2nd '6C' band is also divided into two cyan stripes, and the corresponding vertical bars are striped grey and magenta; (3) the 2nd '6M' vertical bars are also striped grey and magenta. Printed grey text also appears as grey/magenta striped.

Can anyone shed any light on either or both of these problems? Specifically I'm wondering:

(a) Has anyone had a similar experience? If so, what did you end up doing?
(b) With an intermittent fault like this, is it safe to assume the print head is in fact faulty and replace it? Or could the fault lie somewhere else completely?

Appreciate any suggestions or advice. Thanks in advance.

 

[ghwellsjr]

I also had an MP760 that I used for many years but I damaged it by cleaning a print head outside of the printer and not waiting two days to make sure it was thoroughly dry. I also maintained several similar MP780 printers but none of them gave the error message you had. Three of them refused to turn on, although one of them would turn on after leaving it sit for a long time. One of my friends who has one of these MP780's just returned it to me yesterday because it is now complaining about the wrong cartridge which is probably the same message as yours being that it is a slightly different printer.

However, you also have an electrical problem in both cyan nozzles. This cannot be fixed and may or may not be contributing to your intermittent power problem. Another of the MP780 printers had the same problem in one of the cyans and then one day it turned itself off and never came back on again. I eventually got rid of that printer but later I wondered if replacing the battery in the printer might have brought it back to life.

So, at a minimum, you need a new print head which you may be able to get from an authorized Canon repair shop for $50 or direct from Canon. They are also available on eBay. Whether this will fix your intermittent problem remains to be seen. It's a gamble.

 

[warwickt]

Thanks for reply George, much appreciated.

Given the electrical problem in the nozzles, I've taken the gamble and ordered a new print head -- will let you know what happens. I also noted your warning here about the risk of cleaning the print head outside the printer -- I now know of one other printer that died immediately after cleaning the print head with water.

In the meantime, as predicted, the error message has reappeared. Will leave another day (until the new print head arrives) and see if it resolves itself again...

Thanks again.

 

[warwickt]

George, another query on the same subject: I think I am noticing a pattern whereby, after the printer has been switched off for a day or so, the startup process when it is switched back on takes longer than if the printer is switched off and then immediately switched on again (i.e. for a minute or so there are sounds of the printhead moving, the startup screen on the LCD is displayed longer, etc.). I assume that the printer is performing some kind of reset or self-test during this time.

The pattern seems to be that, after this longer-than-usual start-up, the printer functions normally (i.e. no "incorrect print head" message).

Is it possible to manually force the printer to reset itself (or whatever it does during the longer startup) -- rather than waiting a day?

Thanks again for your helpful advice.

 

[ghwellsjr]

I really don't know about resetting a printer. The only thing I can think of is that the printer may be doing a longer head cleaning after a day of idleness. But I don't know how that would have any bearing on the "incorrect print head" message.

The MP780 that my friend wants me to fix displayed "wrong cartridge" when he had it but after I cleaned up the print head and the printer (there was ink on the doors and on the paper tray) it simply said to insert the cartridge (meaning print head) both before and after I put it in. So maybe the print head has gotten worse. I put in a good print head and it proceeded to ask for an alignment. It also has a purge unit problem. So it looks like this printer will not shed any light on your problem.

 

[warwickt]

Just a final follow-up to this thread...

I installed a new print head a week ago -- looks like the MP760 is back to normal operation, i.e. no error messages, test print is as it should be, etc. So it seems that even an intermittent print head error message was indeed indicating a faulty print head in this case.

Thanks George for your help with this problem, definitely worth the cost of a new print head (even to New Zealand!).

 

[ghwellsjr]

You're welcome.

And more information on my friend's MP780: It behaved just like yours in that it would display the an error message after it had been on for a short while but after it had been off for a day it would work again for a short while. I decided to wash the print head under flowing water and let it dry for two days. This time when I put it back in the printer I got the error message immediately. So I too have given up on that print head.