Cleaning the scanning glass

Happened with me too. Turned out to be a small sticky smudge on the ADF glass. That is the smaller glass scan area to the left of the large glass scanning area.
When using the ADF to scan or copy, make sure the smaller glass area is clean along with the rollers.

Hi,

To clean between you need to remove one of the pieces of glass...usually the inside is the best....

There are a few screws on the inside of the door theat hold the frame, which holds the inside glass...

remove the frame and carefully remove the inside glass... clean the inside of the outside glass, then clean the inside of the inside glass and then reinstall the froame over the inside glass...

Now you have a clean ove glass again...

heatman101

Do you see the same smudge mark if you lay the original on the platen rather than using the document feeder? If it only shows when using the document feeder, clean the scanning glass for the document feeder. It's the small glass to the left of the main glass with the cover open. Use a damp cloth and clean off any dirt or white-out.

If the scanner glass or the white scan background (the white portion of the lid) are dirty, the scan might be different than intended. A dirty scanner glass (fingerprints or smudges) slows down performance by as much as half a minute and affects scan quality. Performance slows because the product is actually processing the smudges on the glass. Turn off the product , and then clean the glass with a soft cloth or sponge slightly moistened with a nonabrasive glass cleaner. If there are visible contaminants under the scanner glass, the product must be sent in for servicing. You cannot remove the scanner glass to clean inside.

Reinitialize the scanner by turning off the product and unplugging the power cord. Make sure that all original documents are removed from the product and that the scanner glass on the product is clean. When the power is reconnected and the product is turned on, the scanner recalibrates.

The computer video driver and video settings might change the image appearance slightly. The product scans in 24-bit color. Setting the video display settings to less than 24-bit, or 24 million colors, results in a loss of color information on the computer monitor. The video driver might change the appearance of colors when viewed on the monitor.

You need to clean the glass. Open up the feeder and you have a large piece of glass for scanning and to the left a smaller piece of glass that it uses to scan from the feeder. Clean this smaller piece of glass; even the slightest smudge can leave a black streak.

The service manual is avalable free through Emule:

ed2k://|file|Canon%20PIXMA%20MP750%20MP780%20service%20manual.pdf|1416152|F054D74C11BE5EEAF2F6D203362303DE|/

Here is the step-by-step for taking the glass out of the printer. I think I will take mine to a shop to have it done!

http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00553775&lc=en&cc=us&dlc=en&product=421999

hi im jules_09,the scanner glas should not be remove from the unit because if it is remove you might get a error code,so just get a soft cloth or a any kind of tissue and table tissue will do then apply a glass  cleaner on it then gently rob it on the scanner glass until the glass is clean just make sure the unit is off and ulplug.if the scanner glass is cleaned

This is a pain; MicroTek offers no instructions; proceed at your own risk, etc. Before you start, get some high-quality optics cleaning kit ready to go, and clean the outer glass perfectly, so you don't have to keep guessing whether remaining smudges are on the inside or out. Remove lid by simply lifting to 90 degree angle and then lifting upwards. Remove all cords, so lid is not connected anymore. You need a thick, strong paper clip. Unfold it so one part functions as a handle, leaving a short length suitable for poking into holes. Lock the chassis on your scanner (underside, coin in red button, turn to locked position). Now sit in chair in front of desk. Put scanner with buttons on your lap, glass towards you. Hold hinge side of scanner with left hand. Notice that there is a pin hole just to the outside of each hinge slot. Now comes the hard, you -might-break-something part. Use right hand to insert paper clip into rightmost hole. With left hand, put a fingernail in the gap where the lid is gonna come off. Press firmly (pretty darn hard, in my experience) with the paper clip to release the tab that holds the top in place while pulling with your fingernail. With luck, a slight pop and that side is done. Repeat on the other side. Note: don't let paper clip angle down towards bottom, slip past retaining tab, and poke into something vital. There is also a third clip dead center, but it seems to pop out with little effort. Unfortunately, you're still not done. There are two more clips about halfway down each side, and no visible way to depress them. You just have to lift up with a frightening amount of force until they make a big "pop" and hopefully don't break. Now the darn thing is still hooked at the front (where all the front panel buttons are). You want to kinda lift the back end up, jiggle, and then pull up and back (I busted one of my front hooks before I got it off). Now the top is still connected via a ribbon cable, but you can put the edge of the top into the lip of the bottom, hold the back of the top at a 90 degree angle, and clean that glass with your left hand. Get it perfect, because you don't want to have to be doing this again. I kept a very bright LED flashlight at hand so I could shine it at oblique angles to scan for smudges. Of course, your scanning element is more vulnerable to dust during this whole process, so try to do this in a relatively clean room, and try to get done quick without dumping any dust on the innards. Good luck, and join me in saying "I'll never buy another scanner that isn't designed to let me clean the inside glass!"