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]

:rolleyes: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.:rolleyes:

[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]

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]

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]

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]

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.

[kmcopier]

there is an special docment for this problem. check your techincal information

[Gerry.Fitz]

Hi ya
Would love to check our tech bullitens but as I work for Oce we get no tech info from your selfs it comes from Germany and goes to somewhere in Venlo nether to be seen again...any suggestions would be greatly appriciated
Gerry

[Herrmann]

I have found something, that might help you:

Description
Thick Paper BK mode setting.
Solution
Thick Paper BK mode setting is to reduce banding that occurs 230mm in from the lead edge when printing halftone images with thick paper stock.
Thick Paper BK Mode engages the first transfer rollers on each YMC colors and operates in color mode during printing in B/W mode.
Notes :
1. Use only for thick paper on whichbanding occurs.
2. Sinceprinting in B/W mode operates in color mode, the total counter counts in B/W and the maintenance counter counts in color. It does not develop YMC,
but the life of the developer is shortened since it agitates the developing unit.
3.Concerningcolor printing, after printing more than 1000 sheets in this mode toner scattering or blurred color image may occur.
To enable Thick Paper BK mode, perform the following:
1.Press the Utility button on theMFP and select #3 Machine Admin. Setting.
2. Select #6 Common Settings.
3. Pressthe Next button and select Thick Paper BK mode to ON.
Note : If Thick Paper BK modeoption is NOT displayed, enableit by setting software DipSW 11-5 = 1 (ON).


Hope, this helps

[sbillis]

check humidity and drum memory.

do you have troubleshooting guide?

B：Cause by 2nd transfer Sample No.13
The line occur because speed is slow down in a moment when the thick paper enters the fixing unit

C：Cause by 1st transfer
The line occurs because transfer belt unit shakes when the stiff paper enters the 2nd transfer or
fixing unit. It is occur because the 1st transfer shakes finally
The distance from front edge depends on the color.

D：Cause by 2nd transfer(paper rear edge jumping)
The line occur because shifted by 2nd transfer as a paper rear edge jumps when paper rear edge
passed the guide plate
The line occur stiff paper and distance is 102mm from rear edge


A：Execute the “Automatic Gamma Adj”
★Touch the “Adjustment”->03 Execute Adjust Operation->Touch the “Automatic Gamma Adj”->
Touch the “OK”->Return to the machine state screen
B,C：No countermeasure. Change to soft paper or light paper.
D：Attach film sheet on guide plate before 2nd transfer

[SEnder]

We the same problem with C452, 552, 652 brand new machines. Only in K. Same defect, more visible on thick paper stock. We replaced K module, nothing changes, same.

[dljorg]

Little hard to tell from your image but it looks like a jitter or speed matching problem caused by the transfer belt or fuser interacting with the paper - worse on heavy stock.

Transfer belt unit is OK and rollers replaced? Second transfer too?

KM says this is a characteristic of the machine and cannot be totally fixed. Hmmmmm....

This is a cut from article 40 in the KM Troubleshooting Guide for the C6501:

The next things can be done to reduce it:
• Activate all transfer pinches when making black prints by service setting SW11, Bit 05.
Admin settings: Set Thick paper black mode to ON.
This under [utility] 03 Adm. settings. 06 Common Settings.
Then 1 times pres NEXT. Set it ON.
Normally when you make a black monocolor copy only the black first transfer roller is active. What this does is activate all the rollers. Effect is to put a brake on the transfer belt and hopefully stabilize its speed and reduce the jitter.

• Minimise speed variations by means of service belt line speed adjustment. OK so play with it between -5 and -35 or more if you dare. Check the FD Mag adjustment when you are done so image size is correct.

• Reduce 2nd transfer step pressure.
After enabling by service (SW1, bit0) the key operator can reduce the pressure by changing the paper tray setting.
DIP SW setting shows Process Adjust button in the paper settings. In Process Adjust section there is a setting for 2nd transfer pressure - again the idea is to reduce the possibility of jitter so try normal and light.

• Use different raster Dot 2 / type 2 instead of Dot 1.
This screen is to adjust in:
Utility [button]
03 Machine adm. settings.
01 Sytem setting.
05 Expert adjustment.
07 Quality adjustment.
05 Custom screen.
Then set for Line 2 and Dot 2 the type to TYPE 2.
Changing the print screen can mask jitter marks by altering the pattern of dots laid down by the lasers under some circumstances - definitely worth a try. Change the screens used by the copier in machine admin mode and then select Dot 2 instead of Dot 1 in the print driver.

BEST SOLUTION SO FAR
1. Do all the stuff above.
2. Lie to the machine about the paper weight in the tray - select 81-105gsm. This makes the motors run at high speed - more torque means less jitter.
3. You have to go to the Process Adjust screen mentioned above and raise the fuser temp and pressure to compensate for higher speed and make sure fusing is correct.

This is not a complete fix but pretty darn close.

Best Regards from the snows of Connecticut!

[RRodgers]

Do the Fuser line speed adjustment and that should fix it. Play with it (line speed) until it goes away.