On Wed, 12 Sep 2012 09:02:40 -0400, Phil Hobbs
wrote:

At a guess, there's some crud on top of a colour-calibration photodiode
somewhere inside.
Phil Hobbs

That's not quite what happens when there's crud blocking the photo
diode. When some of the light is blocked to the photo diode, the
mechanism thinks that the printer is printing too lightly, and
compensates by applying more ink to the paper (making a drippy mess).
If the paper looks like there's far too much ink being applied, it's
probably a clogged photo diode.

The only the time there's a change in color balance is when the print
calibration routine is run. It first prints a test page with
psychedelic patterns, colorful stripes, and bizarre blotches. It then
scans the printing with the photo diode and eventually compensates for
any color alignment (convergence) and balance errors. Between
calibration runs and print cartridge changes, it stores the settings
in NVRAM.

However, a 30% difference in color balance is more than what I believe
the printer can normally compensate. Something else is wrong. I'll
wait until the correct model number is disclosed so I don't waste time
on the wrong printer.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558