C352 Lines On Copies/Prints

[JSC]

Yea I agree, i'd start with the Black iu 1st then move on to the transfer belt, but i'd be willing to bet that the black iu is at fault.

[mrfuser]

My hat is off to you all! I ordered and replaced the black IU, lines immediately gone! Still, old IU looks fine. What is causing the IU to fail like that? One minute great copies, the next bad, kinda scarey!

Thanks to all your input!

Kelly

[Stirton.M]

Good show.

The image unit has several areas that can cause this. One is bias failure, in which either the charge unit or the developer mag roller have lost a physical connection to the HV circuit. The net result is an imbalance and toner gets shoved onto a drum that has more positive potential than it should, the developer unit will typically throw developer and toner in great amounts onto the drum, eventually emptying itself. There are variations to this process based on which item lost bias, relative to the rest of the parts involved. The developer unit itself may be completely empty of the developer mixture similar to graphite...think high school physics with graphite on paper, magnet below, graphite stand on end...this process is similar to what happens on the magnet roller, toner rides on the graphite, gets lifted towards the drum, is now referred to as the brush, the higher "positive" relative charge the drum has to the magnet roller, the toner will jump the shorter distance to the drum.

Small theory, drum and developer chamber are at a very high negative charge (electromagnetic induced) at the same potential. Wherever the laser light shines, writing text for example, the surface becomes more positive, relatively speaking, and the toner is attracted to those areas, filling in the written area with black toner to produce the text image. The transfer belt unit has a slightly more positive charge, relative again, that attracts the toner off the drum to the belt. Each colour is overlaid over the other to produce colour blends as needed. Then another roller, with yet again, a slightly higher positive charge relative to the belt, paper rides between and toner is attracted to the paper, where it eventually goes through the fuser, melting the toner to the paper in the finished image.

Another issue, partially related to the above, is that excess toner falls on the charge grid and charge wire, causing an imbalance on the charge, in effect shorting the charge unit against the drum. This part is a bit sketchy as I am only surmising this based on what I know from separate charge, drum, dev unit technologies.

[abilashvk]

Very nice explanation Friend about the Developing procedure.
Apart from this,in tropical countries, where humidity factor is present the charge grid gets corroded as well as the so called 'End Blocks' of corona unit gets fried up.We use to manage by apply slight amount of nail polish/Whitener on the affected portions of grid as well as end blocks & advice the customer for the replacement of IU near future.
These type of complaints might occur all of a sudden also.It can be confirmed by swapping the drum units alone, as naturally lines will appear on next color.Most of the time machine will also show a 'warning indication' on control panel( a P code corresponding to the color of IU which is having the problem.)