Image defect on KM 6501 - OCE-CS665

[resolute]

Hi,

We are having an image quality issue on our KM6501 (branded as OCECS665). I've included a PNG Image of what the defect looks like. It is a line that appears on 17 x 11" or larger stock, the heavier the stock, the more pronounced it is. The line almost looks like a stutter in the fuser, but it isn't. The defect is most pronounced in black. The defect is especially noticable in darker images and photos that have a high black component. However, if you print black only -- solid 100% it is fine. Only noticable in halftones and only in Black. Cyan, Magenta and Yellow do not have this defect.

Tried replacing drums, wires, fuser, trans. belt even the dev housing for black.

Hope someone has come across this, and found a solution.

Thanks

[Stirton.M]

that is a strange problem

I was going to say outright that the problem was the torque converter gear under the fuser....but you changed the fuser apparently?

Check the gears driving the dev assembly inside the back. Not likly, but then I've seen some issues arise from these. Are you certain the other colours are unaffected? Reason being, I have seen this on other machines, something similar, and the band appears at about the same time but roughly the space of the drum surface to belt interval between the 4 drum units, something about 3-4 inches apart though slightly wider.

Restart timing?

Flat spot on roller someplace?

Is this face up or down or doesn't matter?

Also, check belt coupler in back. Is it defective. Refer to TSB and troubleshooting guide for what I am talking about here. Belt unit itself?

[random]

is the lead edge the right hand side or left hand side of that image?

[mrwho]

I had something like that a long time ago (never got to play with those machines again). I don't remember exactly what the solution was, but try to play with the paper tray's process adjustment HV values - try to, one at a time, raise or lower it by 20 or 30 points. I would bet that you'll get it eventually.

EDIT: Try to change "Separation DC" (Front and Back) to -20 or -30.

[texchar555]

ok, if its doing it to all the colors it gotta be tr belt or tr roller. check to make sure that the part that lifts and lowers the tr roller for trouble it could be up and drops. Hey, butt the printed image up against the fruser roller and lay it down . By the looks of the image you posted its a pretty close measure from fuser roller to 2nd tr roller.

[random]

If the line is about 108mm from the lead edge of the image i.e if you use margin shift and move the image towards the trail edge of the paper and the mark moves with relation to the edge of the IMAGE then this is almost certainly the printer control board.

You will have to replace it with a ***NEW*** printer control board, don't swap it from out of another machine or try a second hand one.

[udamanatclines]

First Check

Does it do this consistantly in the same spot always.. Like never moves one way or the other.

what do you see if you open the doors of the machine and look inside while it is running?

Does it happen on all paper stocks?

[don]

Hi

Dear Friend,

Remove the Black Developling powder from the developing unit. Rotate the rollers as per given in the ser manual. Refill the Developer, make a toner density initial auto adj.

This might slove your problem or else just keep printing your jobs. After some printout this band will dispear.

Regards,

[resolute]

Thanks for all the suggestions...

Looking at the image -- the lead edge is on the left side - the defect is closer to the lead edge.

If i move the image (margin shift, etc). the defect remains the same distance from the lead edge of the paper - its saturday today.. so I will have to wait until monday to go in and measure the distance from the lead edge. However, I can tell you that it is more than 108mm -- more like 200mm - sorry my image got cropped from the left as it was on a 330 x 487mm sheet of paper. The defect on that sheet would be about 50mm left from centre.

Have tried to replace the developer.

The defect is on all stocks... more pronounced on heavier stock (ie. 250gsm+). If I print a photograph -- the image defect is somewhat hidden, but if I print a greyscale image or halftone -- it is very very apparent.

[udamanatclines]

you need to look

if the jitter does not move to lead and trail its safe to say its not dv unit or hv unit or anything of that nature.

Open the front door cheat the interlock and shine your flashlight into the space between the transfer roller and the fuser entry plate to watch if the paper stutters. I am not convinced that the problem not of a mechanical nature.

[Stirton.M]

Thanks for all the suggestions...
The defect is on all stocks... more pronounced on heavier stock (ie. 250gsm+). If I print a photograph -- the image defect is somewhat hidden, but if I print a greyscale image or halftone -- it is very very apparent.

Try a mixed halftone, with black and cyan. Pattern 53 and 100-120 halftone on the two colours. I want to know for certain if there is no repeat in the cyan. It seems strange that this only affects black and not the other colours.

Swap the drum drive assemblies between black and cyan.

Also, try a complete belt unit swap.

[Albonline]

this looks like a speed blur to me, which would mean somthing is affecting the speed of the black drum or developer units. saying that the heaver the stock the greater the defect points to paper feed system overload. ie motor drawing too much current or slowing so much that the other motors in the copier cant sync with it.(going beyond pll range)

[Albonline]

hint try running a grid pattern, see if image is distorted.

[Gerry.Fitz]

line

Hi ya
I have had several versions of this problem ...fist can you check if it is media related ..if it is card it will flick and cause a bounce which will give you the line and it will get worse the thicker the card this m/c will only run paper or you have not set your loop or pre registrations correctly.
Gerry

[TonerMonkey]

This is a jitter problem with heavy stock hitting the bottom of the transfer belt causing the mark - a special rom was brought out for the 6500/5500 which racked the CMY transfer rollers out when doing black thus taking the slack up on the belt and resolving the problem.

Best practice would be to make sure firmware is up to latest level. Otherwise I could find out which firmware sorts this problem, it has been known to happen on heavier stock on black only.