BH-C-280, weird pattern

[Hansoon]

BH-C-280, weird pattern.

Machine has a total of 120K on the clock 30 color/ 90 B&W. There's a strange pattern on all kinds of paper, with color and mono, doesn't matter. Internal prints and everything it shows al the time even within the leading edge void. The pattern is very fuzzy and looks like - more or less - squares 4x6mm, near the rear edge. Repeating around every +/- 28mm. Barely visible but enough to be bothering. See attachment. It shows best with halftone pattern 65, yellow. But is not restricted to yellow only. It shows with all colors and all circumstances.

Since the pattern repeats around every +/- 28mm (hard to measure exactly cause they are so fuzzy) I looked for any roller or other thing "round" roughly being 9 mm (28 divided by π 3.14159 = +/- 9mm). Did not find anything. A visible inspection of the fuser, drums and transfer belt did not give any indication. Had no parts with me to test.

Later on back home I recalled that inside the transfer belt are rollers with a diameter of 10mm. Had unfortunately not yet checked if there was a bump of dirt on one of them, when I was there cause the surface of the transfer band looked very clean and the customer wanted to leave. Therefore I could not crash stop the machine to do further tests too.

You guys have any ideas?

20190304_172130.jpg20190304_175914.jpg

Hans

[allan]

Re: BH-C-280, weird pattern

Wanted to mention those rollers but how are they going to produce toner?
Stop the machine after transfer and check. Get this feeling your fuser could be involved.

[Hansoon]

Re: BH-C-280, weird pattern

Wanted to mention those rollers but how are they going to produce toner?
Stop the machine after transfer and check. Get this feeling your fuser could be involved.

Allan I have seen the strangest things coming from the Transfer Band. Could imagine that the haze of residual toner would be enough to stick to the paper if the transfer belt is being forced up by a bump of dirt.

Hans

[allan]

Re: BH-C-280, weird pattern

Allan I have seen the strangest things coming from the Transfer Band. Could imagine that the haze of residual toner would be enough to stick to the paper if the transfer belt is being forced up by a bump of dirt.

Hans

I have also had spots with the same pitch but not the square patches like that. No clue...

[Hansoon]

Re: BH-C-280, weird pattern

I have also had spots with the same pitch but not the square patches like that. No clue...

Coming from the TB?

Hans

[allan]

Re: BH-C-280, weird pattern

Coming from the TB?

Hans

Nope coming from the fuser. Stopped the machine mid print and nothing from the transfer belt.
Not to sure about the makeup of the fuser and don't have one to check.
Costumer did not complain so i opted not to strip the fuser.
On the next call the marks were missing.

So here is a math problem.
If those marks are offset from some thing like the transfer belt or the fuser belt. Then the pitch can not be 28mm consistently if its from the fuser there is no blade to clean it off so every so often the pitch will be less than 28mm and don't want to believe that pitch would be a factor of the fuser belt lenght. then transferring to the paper in witch case it should run out of contaminant soon.
From the transfer belt they can remain constant because every new cycle gets cleaned off.

Now i have confused myself....

[tsbservice]

Re: BH-C-280, weird pattern

Allan I have seen the strangest things coming from the Transfer Band. Could imagine that the haze of residual toner would be enough to stick to the paper if the transfer belt is being forced up by a bump of dirt.

Hans

I would think the same 👌

[blackcat4866]

Re: BH-C-280, weird pattern

You might want to look at the primary transfer belt. Back when I worked on Sharps, it was a relatively common problem. Toner would collect inside the transfer belt, build up on the facing roller, then press a repetitive texture into the belt. Since the facing roller diameter is not an even factor of the length of the primary transfer belt, the longer it was allowed to run this way, the more complex the pattern, and the closer the repetition. Personally I'm leaning towards the black primary transfer roller. =^..^=

[allan]

Re: BH-C-280, weird pattern

Any noise or vibration going in beat with that would be something i would listen and feel for.

[Gaffers01]

Re: BH-C-280, weird pattern

Could be the k developer roller, i know its a different diameter but i've had a similar mark before and after cleaning the dev roller mark disappeared.

[Hansoon]

Re: BH-C-280, weird pattern

Could be the k developer roller, i know its a different diameter but i've had a similar mark before and after cleaning the dev roller mark disappeared.

Thanks, but K-Developing roller should not come into action when making Half Tone Test Patterns CYM I believe. K-Transfer roller inside the TB yes, since it is constantly engaged.

Hans

[Gaffers01]

Re: BH-C-280, weird pattern

the k drum is always in contact with the transfer belt, thus the k dev roller would be too.

[allan]

Re: BH-C-280, weird pattern

the k drum is always in contact with the transfer belt, thus the k dev roller would be too.

Does not mean it rotates, but not sure myself.

[Gaffers01]

Re: BH-C-280, weird patternhttp://www.copytechnet.com/forums/images/icons/icon6.png

Does not mean it rotates, but not sure myself.

Im pretty sure there is only 1 drum drive motor on those machines, the k drum is always on and a clutch turns on to rotate the colour drums.

I wouldn't bet my life on it though

[Hansoon]

Re: BH-C-280, weird patternhttp://www.copytechnet.com/forums/images/icons/icon6.png

Im pretty sure there is only 1 drum drive motor on those machines, the k drum is always on and a clutch turns on to rotate the colour drums.

I wouldn't bet my life on it though

You are right that the K-Drum is being driven constantly by the main motor M1 which also drives the TB and take up stuff. This likely to avoid that the TB - which is constantly moving - would rub the surface of a not rotating K-drum on one spot since the K-Drum's 1st transfer roller is always engaged as you mentioned.
So both the TB and K-drum are driven constantly and synchronically. The CYM drums are not. They all use one motor the color PC motor M2. The 1st transfer rollers inside the TB for CMY are engaged/disengaged when necessary.

However, the K-Developing unit is not driven constantly, it has its own clutch. Therefore we can almost sure take out of the consideration that the K-Units are being the cause when strange patterns in CYM appear. To complete the picture: The CMY developing units are rotating with the previously mentioned color PC motor M2. Torque to the CYM developing units is coming from M2 and being distributed to the CYM developing units by the Color Dev.Unit Engaged motor M10. So they all are only activated depending on the demand.

Thanks for thinking with me.

Hans