Michael Brown said:
I had made a request to Canon as to the cause of the problem. Their
first reply telling me to inspect the tank seating, printhead seating,
and a do a few deep cleaning cycles - all of which I have done numerous
times. If my problem still continued it likely was the printhead and I
was given a number to the parts department.
Below is my reply to Canon on what I found when I took the printer
apart:
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What I'd really like to know is how does the cross
contamination occur? I've had the yellow tank contaminated three times
now. In all cases I thoroughly rinsed all ink from the print head (I
even removed the two screws holding the print head to the plastic
carrier and rinsed the rubber washer between the printhead and the
carrier). After doing this the printhead printed fine with fresh ink
tanks. I don't see how any cross contamination can occur in the
printhead - each color ink has a separate path to the print head.
I've now disassembled the printer - with particular attention to the ink
waste area. Printers are second to VCRs in the wonder of their
mechanical design! I read one post on a newsgroup saying the hoses on
the ink pump get brittle - mine were just fine - soft and supple. The
pump appeared to work when I manually turned it - ink came out the tubes
on the bottom side. Possibly the small rubber trays that raise up and
sealed against the bottom of the printhead are not making their seal - I
would have expected to find a pool of ink in the trays if that was the
case - there was none. I re-assembled the printer with new tanks and
its currently printing correctly.
But... as before, if I let it set for a few hours, the yellow will print
green. I'm sure if I let it set for days, the cyan would be leeched up
into the yellow tank as it has done three times already. I did run the
printer with the cover off and watched the printhead park. It appears
the rubber trays are raised to seal the printhead when not in use. This
is the only time there is an direct path between the cyan and yellow
tanks. When the printer sits for a long period, can the inks possibly
slowly drain from the tanks into the rubber trays sealing the bottom of
the print head - filling the tray - and seeping back up into the other
color tanks?
Obviously with the thousands of the i850s/i860s Canon has sold, I know
I'm not the only one to experience this.
Can Canon offer an explanation? What specifically can cause this? I
don't see how a new printhead can correct this - if so, what failed in
the printhead? There just isn't much there to fail. I'd hate to spend
$52 on a new printhead when I can buy an ip3000 for $80.
While it would be great if they could, they can not possible answer such a
question accurately via phone or email.
having worked on more of these and other printers of similar design more
times than I can count, the most that can be offered without a visit to a
service center is 'possible' causes, which I and others have already
mentioned here in the newsgroup.
There are actually fine adjustments (and tools for doing so) in the areas
you disassambled. Could be that one of these is out of spec, could be a bad
printhead, could be bad ink or tanks. Often third party inks will refill
salvaged tanks and in doing so disturb the precision purge/weep hole at the
top of the tank. This can in fact cause the ink to excessively build up in
the waste/purge vavle area near the home position. So yes you therory there
is also possible.
At this point you have 3 options I can see.
1) Replace the printhead and hope that is the cause (most likely by the
way).
2) take it to an authorized service facility where they have the specs and
tools to properly diagnose and fix.
3) take advantage of the Canon loyalty program where you get a discount and
free next day shipping on a replacement printer (I have used this myself).
Of couse I haven't told them I have been using generic ink tanks - that
too easy of an out for them. (I've gone through one set of generics
before my problems started) If my theory on ink pooling in the trays
when the printhead is parked is correct, a thinner ink might be to
blame.
Possible, or an ink with to rich an ethanol or glycol content may have
caused premature drying/shrinking of the 'O'-Rings in the printhead allowing
the inks to mix.
Interestingly enough - I contacted the generic ink manufacturer
(abcink.com) and explained the problem - they apologized for my having
problems with their product and offered me a credit on my order...
More than most will do and one reason they can sell so cheap. They have no
liability should the printer fail as it is usually more costly to prove
their ink was the cause than to just replace the printer and they know that.
