KM C451 ghosting problem

[kico-abaco]

It is ghosting only black color and ONLY when duplexing (first side is OK, just second side is ghosted).
Black parts of print looks like smeared in direction how paper moves through printer.
Printer is 5 years old and has 200.000 prints, I use Katun toners for past 1,5 years.

Any suggestions?

 

[Slyman]

Suggestion ?? Yes, first, put OEM toner, even it's Katun toner work fine since 1.5 year, they change the receipt of mixture once a while and it give you some bad quality sometime.

But you can also try to readjust the 2nd side of 2nd transfer voltage. This depend also of what kind of paper spec you have.

 

[OkiTech]

At that mileage, you actually might have a bad fuser. The reason why only Back toner - well it could be because it is layed out most dense - or worse - built out of CMYK. The fact that you use aftermarket toner does not help to trace the problem even if you swap with OEM, it will be some time till it shows due to some toner remaining in Developer unit.

 

[kico-abaco]

Thnx guys for your suggestions.
Today I tried printing different paper stocks and noticed that only thin papers are smeared (80 and 100 gsm). Thick papers (170, 200, 250 and 300 gsm) are printed perfectly.
Is there any part which automaticaly adjusts fuser (or any other part) pressure depending on selected paper thickness?

 

[OkiTech]

Fuser is springloaded under constant pressure, the temperature of upper fuser roller and printer's speed varies according to the weight of the paper.
That should be set accordingly in correspondence with paper's specs. Also - please take in to account that what might be playing the role here is the paper itself rather it's thickness, try similar thin paper but different brand to see if it changes anything.

 

[kico-abaco]

Tried different brands and it's the same on all of them - on every brand 80 and 100 gsm smeared, 170 and thicker are printed perfectly.
Printed 80 gsm but set as 300 gsm (Thick 4) and it's smeared/ghosted too. I'm just printer operator with zero service experience but to me it looks like it's something with fuser and paper thickness matching/adaptation.

 

[OkiTech]

Ok, so look, #80 cover is lot less than 300gsm, you might be overcooking your toner, if you run #100 text or #80 text, try to set it to where it has to be "Glossy media" medium weight or try medium-light, see what happens.

 

[kico-abaco]

Tried every combination of paper and set thickness I could imagine and it's always the same - duplex side of 80-100gsm paper smeared/ghosted, 170-300 gsm printed perfectly.
I stopped printer while duplexing, pulled paper out and noticed that part which went through fuser is smeared and one that didn't is OK.
So I believe it's something with fuser but don't understand why is it only black toner and only when duplexing.

 

[OkiTech]

Look, do this if you can - convert that black to be 100% Cyan or 100% Magenta - it may do the same for the reason (I it is somewhat guess because I don't see your image) that Black text for example, may have a 100% fill meaning descent amount of powder on a given spot and color, most of the times are built out of CMYK screens and amount of toner powder on the a single spot may not be so high. Also it could be that K toner formula isn't correct and it needs a higher fusing temp - than question comes - why on back side only. What if you set the machine to print/think paper that is 1 step heavier, say 140 gsm and still run #100 gsm? Also can you scan and post the sample of Ghosting - I'd like to see that.

 

[kico-abaco]

I'll scan and post picture first time in the morning, it's 10pm here in Europe.
All other colors (100% C, M and Y also) are printed OK.
Black elements of duplex side are smeared even if text is just 30% black (grey).
I tried every combination I could imagine: printing as cmyk and just K, color and greyscale printing, automatic and manual duplex, different brands of paper, reducing toner coating in printer driver, printing text filled with every gradation of K color (100 to 30%), set the machine to think that 80 and 100 gsm paper is 1 to 5 steps heavier, glossy mode on/off, Pure Black on/off, 2nd duplex side paper on/off...
I suppose that bad toner or imaging unit would manifest as problematic printing/smearing/ghosting no matter what side is printed, and this is just duplex side so I must say it's driving me nuts grrrr

 

[OkiTech]

Ok. Please do, it will be easier to think of solution actually seeing the problem.

 

[kico-abaco]

Here it is. Hope it will help...
http://imageshack.com/a/img31/9041/sqqs.jpg

 

[OkiTech]

Ok, Ghosting is out of the door as it is usually the situation where toner sticks to the fuser and repeats on the next rotation means that if it would be the fuser, Image defect would repeat every Pi x R^2, not immediately. I would suggest to check environmental factors:
Than machine is properly grounded and that it is no too cold where machine and paper is, humidity should be within range specified by manufacturer. It looks more like toner puffs up from the surface of the paper due to abnormal static discharge. The should be sort of a brush near the fuser exit that attached to metal plate and to the frame of the machine - make sure it is intact.

 

[Slyman]

UnlimitedBT got good suggestion but you may also have an overcharge somewhere with the black unit...Those machine apply different charge for 2sides and type of paper, one of those is probably too high.

Did you change your transfer roller since a while ?

 

[kico-abaco]

Sorry guys for such long time, I forgot to reply...
It was transfer roller issue, changed it and now it prints fine

 

[Aries]

Hi guys, I'm new to this forum. Could you please help me with this same problem that Kico-abaco encountered. Unfortunately I do not know what the transfer roller looks like. Where to look for it so I could replace it?