Canon PIXMA MP780 - Inconsistent Color Printing

[roland6543]

Im going to apologize up front for the length of this email and the many questions. There is a lot of info on this website. I have tried most tips, but I have still been unsuccessful. Before I spend money on replacement parts or ditch the printer, I would like to know if anyone could pin down the problem from my description below.

Essentially, on any given day, certain colors do not print or they flood the other colors. Often, I think I have the problem fixed, only to find that 2 days later, printing is very poor.
I have a test print of 4 blocks of color and some text that I run every few days.
Frequently, there is too much magenta it bleeds into other colors
Very often cyan does not print at all. Sometimes yellow and black does not print.
The black from the large cartridge is always OK

I am using refilled cartridges which I have refilled many times.
After reading that cartridges may need cleaning, I have also flushed out the cyan and magenta cartridges.
I have also attempted to clean print head by trying to flush the ports (with both water and isopropyl alcohol) where the cartridge outlet fits in, but I dont know how successful this was. The cyan line did seem a bit blocked to me (although some cyan did come out of the print head jets). I have also soaked the bottom of the print head in water overnight.

I am at the point where I will try anything. I was thinking I should try flushing the print head again perhaps with Windex or mild ammonia, and buy new cartridges. Buying new cartridges is an expensive experiment if my printer is dying on me.

All advice very welcome.

 

[Smile]

You could have bad seal on your cartridges as you don't use OEM cartiridges.
You could have print head internal leak, that can lead to color mix as you describe.

 

[roland6543]

I'm using blue plugs which I thought were sealing OK. Would tape be better?

 

[jflan]

I'm using blue plugs which I thought were sealing OK. Would tape be better?

With color conrtamination as you describe, one of the suspects can be the cartidge seal.
Not the seal where you refill into, but the seal where the cartridge outlet port meets the printhead.

A few things to consider:
A cartidge that is over-filled and not "milked" can cause flooding which leads to contamination.
A cartridge that has a defect at the outlet port can fail to seal.
A cheaply constructed aftermarket cartridge can fail to seal or worse.
A sponge that has been pushed upward during a flushing session can flood the printhead.
A cartridge with a plugged breather vent can fail to deliver enough ink when called on.

It is possible that your problem cartridges have reached the end of their service life.

 

[pharmacist]

That's the reason why the german durchstichmethod is superior to the normal filling with ugly plugs. The durchstichmethod automatically ensures the optimal pressure inside the sponge without the danger of overfilling with no need to milk the cartridge (will wear out the side walls by repeatedly pressing it together). Just let gravity do its work and the ink will search the optimal balance inside the sponge. And you don't have to be afraid that the cartridge is not properly sealed above the ink chamber as you don't make any hole above it ! And also: it looks more elegant without any ugly plugs on the outside.

 

[roland6543]

I think I will order some new OEM cartridges. Then if that solves the problem (i.e. I know it was the cartridge and not the print head), I will try the durchstichmethod for future refills.

Should I try anything else before purchasing new cartridges (I have to admit, I'm still not 100% sure that my print head is not blocked).

 

[Smile]

durchstichmethod is superior to the normal filling, but you must take caution where the needle goes, if you miss the sport and go a bit higher then the cartridge can provide too much ink and or leak.

 

[roland6543]

Some quick feedback.

I gave the PH a thorough clean:
Flush with water, then windex with ammonia, then water
Blew out with air, then flushed with IPA, then air dried.

Result: Blue still not printing consistently.

Then:
Bought a Canon Cyan cart; Clean - alignment very poor
Deep clean (pity about wasting new ink); PH alignment
Now printing looks good.

I will monitor for a few days and see how things go.

Thanks for your help.

 

[roland6543]

Just wanted to post the latest news on my problem:

I have no more problems

Printing is great. I really thought that my PH was totally screwed, but after a good clean and a new cyan cart, things are printing great, day after day after day

Thanks everyone for your advice

 

[Smile]

Just wanted to post the latest news on my problem:

I have no more problems

Printing is great. I really thought that my PH was totally screwed, but after a good clean and a new cyan cart, things are printing great, day after day after day

Thanks everyone for your advice

I think you had bad cartridge seal then.