repeating digital pattern on a Bizhub C364

[Makinbacon]

I was wondering if anyone has seen this before. This is a repeating pattern that looks to be digital not mechanical. We have replaced the following:
Image Transfer Unit
All Drum and Developer units
Laser unit
KMBS said to replaced the power supply... we did.
Next they say to do the memory. I personally do not think it's a memory issue. I have been wrong before...
Hopefully you can see the spots on the images attached. You may have to zoom in on the image to see them.

[allan]

Re: repeating digital pattern on a Bizhub C364

Does this appear on copies too?

[Makinbacon]

Re: repeating digital pattern on a Bizhub C364

Does this appear on copies too?

Yes. I forgot to mention that it only happens on color prints and copies. If a bw job is run its fine. It only has about 12k color on the counter. It feels like a symptom of something else. Like, if you do not run through the setup procedures it leaves lines on color copies. But this is copies and prints.

[allan]

Re: repeating digital pattern on a Bizhub C364

It does look like noise, are those spots black or dark grey are they raised? If i would change something to test it would be the MFPB. I give up that is too unreal.

[allan]

Re: repeating digital pattern on a Bizhub C364

Argg that does not make sense. Take a very high res image with a camera with plenty of megapixel.

[allan]

Re: repeating digital pattern on a Bizhub C364

Blank of all the other lasers slits with black insulation tape and run the same test. If its still there you can rule out any processing problem. unless they come out magenta ???

[Makinbacon]

Re: repeating digital pattern on a Bizhub C364

Blank of all the other lasers slits with black insulation tape and run the same test. If its still there you can rule out any processing problem. unless they come out magenta ???

We assume that the machine is putting the spots there. We also assume they are coming from the black drum because the machine is writing them there. But we replaced all of them. We did run yellow and cyan prints and got the same result with the spots. We removed the surge protector and it did not help. I scanned these images in on a C452. I tried different resolutions. I wanted a clear enough picture to see the spots but was worried about file size.

[blackcat4866]

Re: repeating digital pattern on a Bizhub C364

I know that you already replaced the drums, but the repetitive nature of the problem points back at the drum. what is the interval on the repeat? =^..^=

[wseyller]

Re: repeating digital pattern on a Bizhub C364

You say it doesn't happen with black only prints which makes me think the black drum itself is not the cause. I think the black primary transfer is engaged at all times. I bet the laser is writing this pattern to the drum. What Allan suggested is a troubleshooting method to help determine if that is true. If it is coming from the laser then you can eliminate half the machine. Because then you are looking are the laser unit, ribbon cable, prcb and MFP.board. You would eliminate everything involving the electrostatic process and fixing.

[yianni]

Re: repeating digital pattern on a Bizhub C364

I've noticed two interesting issues.
1.. In the first photo the blue area doesn't have this noise.
2.. It seems there is a repetitive pattern. The two areas marked as black rectangles, -in the second photo in magnification-, someone could see the same pattern of dots. Almost all color copiers use a method for identifying the serial number -in every color page- using yellow dots that are not visible with bare eyes. It seems, -in your case- like the yellow dots are replaced with black dots. I suggest to scan only a small area (e.g. 3x3 cm, 1x1 in) in the higher resolution, like 2400 dpi.

[Foxhound]

Re: repeating digital pattern on a Bizhub C364

A good look under a loop would help clarify what exact colors are being layed on the image. Check filters are good and start checking transfer voltages. also i have seen toner/dust coat the boards in the back layering on process chips causing unexplained quality issues.

[Makinbacon]

Re: repeating digital pattern on a Bizhub C364

A good look under a loop would help clarify what exact colors are being layed on the image. Check filters are good and start checking transfer voltages. also i have seen toner/dust coat the boards in the back layering on process chips causing unexplained quality issues.

We have replaced the MFP(Main) board already. I think I forgot to list that. I am inclined to agree with you that a loop may be out of adjustment. KMBS said to replace the Memory Module so that is next as it arrived yesterday. I suggested a factory reset. At least its under warranty and we get all these non consumables for free. I am posting for another tech at my company. I still think it is software/firmware related. Such as a setting or adjustment out of spec or tolerance.

Thanks for all the replies. Still open to suggestions.

[EarthKmTech]

Re: repeating digital pattern on a Bizhub C364

Id be considering replacement of the ssd module and a factory reset and reconfigure.

it looks a hell of a lot to me like its overlaying the serial number in the wrong colour in colour prints, it is supposed to be yellow so as to not be visible.

[Makinbacon]

Re: repeating digital pattern on a Bizhub C364

The tech did cover the black laser window and still got the dots. So The grey dots are a mix of CMY. Could this be caused by line noise? He has moved the machine to a different outlet on a different circuit and copy quality got worse. Black prints got blurry.

[yianni]

Re: repeating digital pattern on a Bizhub C364

The tech did cover the black laser window and still got the dots. So The grey dots are a mix of CMY. Could this be caused by line noise? He has moved the machine to a different outlet on a different circuit and copy quality got worse. Black prints got blurry.

My english is not very well, and may I haven't explained it correctly. It seems it's the serial number used to printed with not visible yellow dots. It seems it's this https://w2.eff.org/Privacy/printers/docucolor/ .

EarthKmTech said: it looks a hell of a lot to me like its overlaying the serial number in the wrong colour in colour prints, it is supposed to be yellow so as to not be visible.