How to access the ink pad on Canon MX850?

[heaser]

My Canon MX850 often has a thick line of black ink on the reverse of the page that has been printed - the line of ink gradually fades away but carries on over a few pages before it goes completely. I have spoken to a repair person who thinks that the Ink pad may have shifted - certainly the ink line was at its worst after changing the cyan tank.

Does anyone know how I can get hold of a manual that will show me how to dismantle the printer and get to the ink pad?

Thanks
John

 

[ghwellsjr]

I think he is talking about the piece of black foam rubber that is easily visible when you open the cover. It goes from one side of the printer to the other. It is there mainly to absorb ink when you are doing borderless printing. However, I don't see how it could have shifted. Just look for any kind of debris that might be sticking up in the vicinity of the black line. After the line fades away after many pages, does it come back? What makes it come back? Starting a new print job? Are you doing two-sided printing? Does it make any difference if you feed paper from the rear or from the cassette?

 

[panos]

There is a cleaning tool in the driver's maintenance tab. "Bottom plate cleaning"

 

[Manuchau]

Some ink may be slowly leaking from the printhead when your printer has not been used for a while, in which case it might cause a splotch on the underside when you start printing, since it seems to go away after a few prints. Try a different genuine or refilled PGI-5 cartridge and see if that makes a difference....some compatibles are not a perfect fit.
Good luck!

 

[heaser]

Thanks to everyone for the suggestions. We have done the bottom plate clean - no effect.

The printer is used by several people so it is a bit hard to track down cause and effect. It is likely that the problem started about a month ago after the main black ink tank was changed - we only ever use genuine Canon products (at least we think they are genuine - are there convincing conterfeit tanks being sold?). The line of ink starts 5mm wide and very dense - it certainly looks like a blob of ink that has found its way on to a roller - it makes elongered oblongs about 40mm (1.5") long down the page that rapidly fade but take about 3 pages to clear completly.

We do use the duplex feature but the problem occurs on both single and double sided printing. My best guess is that the problem is related to how long it is since the printer was last used - the longer the interval then the more likely there is to be a problem - once the blob of ink has been spread over 3 pages then the next prints are ok. The exception to this is that there was a very dense black line after the cycan was changed - the printer had been used recently.

I will try changing the black tank.

John

 

[websnail]

You could also check that you haven't got a damaged black rubber grommet in the printhead itself..

My guess is you're already on to the real culprit though.. If you're under warranty though, phone Canon and see what they say... They may offer a new printhead and/or cartridge.

 

[heaser]

I have tried 2 new black tanks from different suppliers with no improvement. The printer can print 10 or so pages OK and then the head visits the right hand side (beyond the paper) and I assume it does some sort of clean. After this there is a thick line of ink down the back of the page - it takes about 3 pages to fade away. I can just reach a small pad down to the right and dab it with tissue - it is running with black ink. So it seems to me that too much ink is being flushed through the head and it sits in a pool on the pad and somehow gets onto the rollers and then onto the back of the page (about 70mm from the right hand edge).

I can't find anyone who sells heads or service manuals or ink absorber pads for the Canon Mx850 - I have read the sites in websnail's sig but can't see anything there to help me! It is beginning to look like I bin a very large MF printer for what I suspect is a small problem. Any words of advice please?

 

[ghwellsjr]

Sounds to me like a clogged purge tube. If you see liquid pooling on one or both purge pads, then that means the peristaltic pump is not working. It has a tube going from the bottom of the purge pad down through the pump which pinches it and moves downward causing a sucking action. I would take some tissue or paper towels and soak up as much as I could, then put some Windex on the pad and see if it is sucked away during a cleaning cycle. If it remains, then just leave the printer alone overnight and repeat at least once a day and hope it eventually clears up.