IR 4251

[Gina82]

Canon imageRUNNER 4251 makes good quality copies when processing job one at a time, or if doing one job multiple times but when I need to duplex a two side image, the top part of the page is fine but the image on the back side of the page are light.

[Phil B.]

Canon imageRUNNER 4251 makes good quality copies when processing job one at a time, or if doing one job multiple times but when I need to duplex a two side image, the top part of the page is fine but the image on the back side of the page are light.

sounds like 2nd side transfer is failing.

have you done a "stop test" to see if the image on the belt is light also? there SHOULD be a 2nd side density adjustment in service mode.

[guitar9199]

Is this on copies, prints, or both?

If only on copies, does the machine have the single pass document feeder?

More data....More data....

[sal]

check your developer it may not be getting enough toner , run 2 or 3 sky shot is it solid have you replaced the charge ?

[roho]

4251 has a primary transfer roller in lieu of a ETB and I believe the single passduplex feeder is not a option. Is this copy or print? Each has their own imaging process. If print only, I would run some pg tests in simplex (single sided) using pg 2, and 1 test patterns a few times and set them aside. Then I would run the same patterns in the same sequence using duplex to confirm that your symptom is indeed what is happening. Need to rule out either the image process mechanical parts or possibly the main controller. Does every single side and first side look ok and only the second side every time? Or is there no real pattern? The latter indicates a mechanical or physical issue, the former leans toward a controller issue.

[Gina82]

It's a pattern. If I run multiple of one image on the platen glass when making a copy, the images are fine and evenly dense. When I use a two sided hard copy and run it through the document feeder which is a DADF-AG1 (Duplexing Automatic Document Feeder) the front side of the image was dark as the original image but the back side was so light it was hardly visible . I replaced the transfer roller yesterday and tried running multiple copies of one hard copy, as well as a duplexed image and the copies of the first original hard copy were lighter than before I changed the transfer roller , but when I looked at the copies of the duplexed image both sides where even and visible but the images where also lighter than the front side of the original copy. After changing the transfer roller, I noticed faint impressions of letters on both side of the copies, hardly noticeable but annoying. The drum is past its rating and so was the transfer roller. The drum is 178k past its last change.

[Phil B.]

It's a pattern. If I run multiple of one image on the platen glass when making a copy, the images are fine and evenly dense. When I use a two sided hard copy and run it through the document feeder which is a DADF-AG1 (Duplexing Automatic Document Feeder) the front side of the image was dark as the original image but the back side was so light it was hardly visible . I replaced the transfer roller yesterday and tried running multiple copies of one hard copy, as well as a duplexed image and the copies of the first original hard copy were lighter than before I changed the transfer roller , but when I looked at the copies of the duplexed image both sides where even and visible but the images where also lighter than the front side of the original copy. After changing the transfer roller, I noticed faint impressions of letters on both side of the copies, hardly noticeable but annoying. The drum is past its rating and so was the transfer roller. The drum is 178k past its last change.

1st thing to do whenever having CQ/PQ issues is to remove from the picture any overlife or near life items.

[Desert Rat]

Phil B.
That's the first thing I do, then start over if the problem is still present. I know that when the primary roller in the drum gets dirty both sides
tend to be lower in density.

DR