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02-18-2011, 06:22 PM
hello, sorry for my bad english, i have new bizhub c280, there is 33000 A4 on counter, nothing changed yet. i have problem with printing magenta. here is some tests A3, 100% magenta is ok, but low density magenta is printing with gradient from front to rear.

please tell me what can i do to found the problem unit? clear the corona? does it help? or change drum unit? or developer unit? if it is developer problem than why 100% magenta is ok?

02-19-2011, 02:10 AM
change the magenta drum unit (the unit comes with developer, drum, charge corona) when you do also clean the cavity the unit sits in

02-19-2011, 06:03 AM
i changed position of cyan and magenta photo drum units but nothing happens, so i guess it is developing unit problem yes?

02-19-2011, 05:51 PM
Assuming the PH glass is clean then yes, dev unit is most likely cause. I`ve had problems with the dev units causing faded areas similar to this. Some times you can clean the units by running a folded sheet of paper between the dev brush and the H cut plate.

02-19-2011, 07:04 PM
ok, first of all i decided to remove dev unit and look at starter on magnet roler, if developer is collected on front side maybe gently shake will help to move developer to rear side.

i have one qestion, after removing an instaling sam developer unit is it nessesary to make some adjustments frome service mode? and if yes, what operations i have to make in service mode?

02-19-2011, 11:10 PM
You should not need to do anything other than let the machine adjust on its own. Reset and Stabilize is typically done when the machine detects the removal of an image unit. In the end however, I suspect you may have to replace that unit if a visual inspection of the brush, drum and charge unit to not show anything amiss. Cannot hurt to ensure the laser glass is clean as well.

02-22-2011, 06:28 AM
i removed developer unit and as you say visual inspection of the developer unit give nothing. there was only a little bit of white dust of paper near magnet roller and blade. how remove this dust i dont know.
i want to ask one questioin. how can i clean the laser glass if cleaning jig on it does not help.

02-22-2011, 01:31 PM
today i changed magenta developer unit with not new one but same test printed on it was good. after i instaled unit in my printer nothing changed, magenta prints still same bad as it was on old unit. so please help me to detect the problem. is it dirty laser glass? and how can i clean it? there is no good serviceman and i have to do this myself. i have service manual.

02-23-2011, 03:10 PM
Pull out the unit, get a flash light and look in through the opening to peer along the glass. Outside of this, the only solution I can recommend is to contact a service guy to directly look at the machine to see what else might be causing the problem.

02-24-2011, 08:03 AM
no glass is clean. i removed the belt, and clean two optical density sensors under belt. after this i got some better prints. but in the rear side roblem does not go. so i think to loook at the rollers inside the belt, above each unit. may be it helps.

here is my problem

02-24-2011, 08:49 AM
Is the magenta test print from the test mode? If from the test mode it is normal if you reduce the density. Did you try to pump in toners(CMYK) and do the gamma adj?

02-24-2011, 09:37 AM
yes in first post magenta prints are from test mode. first print is magenta density 255, second density 60 and third is lattice patern revers density 60

02-25-2011, 03:57 AM
All machine using transfered belt will have this type of uneven. Suggest you service the transfered belt(especially the cleaning blade) and check is the life span due. Sometimes after servicing the transfered belt and pump in toners(CMYK). the print will improves.

02-25-2011, 03:59 AM
if that the cas,e there is nothing wrong with your magenta unit. Do concentrate on your transfered belt and do some service on it.

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