Bizhub C350 Colour Problem

[bserbet]

Hi!

I have Bizhub C350 in my office and there is a colour problem for the last few days.

At the attachment there is the test page and 4 other A4 pages I print from my copier which will help you understand my problem clearly.

It is not a good scan but as you can see at the attachment, at the top side of A4 papers there is an area about 5 centimeters width and it continues along the page and in this area green and blue are bad, at the rest of the paper green and blue printed correctly. No problem seen at red and black.

I cleaned the copier completely after this problem occurs but nothing changes.

Does anyone have any idea about it?

[mrwho]

If I had to bet on it, I'd put my money on the cyan IU being defective. Take a test print using CMYK, a color in each page (you know the drill: one page with C, other with M, etc).

[blago_vd]

As I can see You must change Imaging Unit Cyan - there is a problem with the qantity of developer in it.

[RRodgers]

One thing you can try is to take the Cyan Imaging unit out (NOT the TONER) and give it a really good shake. Be sure to cover the hole that the toner is feed into so it won't come out. "Sometimes" they will come back. (rarely)

If not, replace it.

[bserbet]

Thanks for your replies. I made the CMYK test prints ans result is as seen in the image. But I haven't shaken it yet I will try when I have some free time. Do you think replacing cyan IU is the only solution?

Test CMYK1.jpg

[Stirton.M]

More than likely the only solution is to replace it.

On the rare occasion I was able to recover image units that exhibited this. For example, a c350 had all 3 colours that were affected, black was still fine. I suspect the IUs were not fully seated and the machine was unable to properly regulate the toner level inside the IUs. I reseated all of them and then reviewed the TCR level history and found that all 3 colours were at about 1% TCR, which they should be at about 7-8%. I did a toner add command and waited, and waited and waited a very long time...20 minutes if I recall, but eventually the machine was able to recover and gave me great solids in all the colours.

Since you have little to lose aside from a few minutes, you could try doing a toner add sequence and see if that recovers the IU.

[bserbet]

I did a toner add command and waited, and waited and waited a very long time...20 minutes if I recall, but eventually the machine was able to recover and gave me great solids in all the colours.

Could you explain me briefly how I can do this toner add command? I am not a technician, just an office user who has interest in this copier. I have the service manual in my computer so if you tell me in which chapter I can find information about this process, I can also do it.

[mrwho]

If I remember correctly, on the Machine Adjustment there should be an option called "Replenish toner" or something like that. If it's not on the Machine Adjustment, check around - you should find it.

You just have to check the color(s) you want to add toner to and press the Start button - the machine should stop automatically after the toner add.

[DelawareJim]

I had this same symptom about a half dozen times on different C350's. Different color unit each time....this time yellow, next machine magenta, etc.... I would run a test print from the service mode for each color. This tells you what developer unit to replace. After a week or 2, I was having to go back and for the same issue. And replace the same developer unit. For the same issue. Those image units are expensive. Here is what I finally realized : the cause of this was crappy aftermarket toner. The toner cartridge was completely empty and it did not signal the copier that it was empty. (There is a small clear window on each toner cartridge. When the toner runs low, a little wiper blade begins to wipe the window clean. When the toner runs completely out, the wiper should wipe that window clean. The out of toner sensor then detects the out of toner condition. ) On these toners the window was not wiping clean so the machine thought that it had toner. Eventually, pulling developer out of the unit. LESSON LEARNED.....STICK WITH GENUINE OEM KONICA MINOLTA TONERS. By the way, a quick way to tell which cartridges you have loaded in the machine......OEM toner cartridges are black in color. Aftermarket toner cartridges are clear.

[Stirton.M]

Could you explain me briefly how I can do this toner add command? I am not a technician, just an office user who has interest in this copier. I have the service manual in my computer so if you tell me in which chapter I can find information about this process, I can also do it.

In tech rep, image process adjust, then TCR toner supply.

[bserbet]

Today I replaced the cyan imaging unit and everything is OK now. Thanks for everyone who shares their opinions with me under this thread.

[RRodgers]

Anytime!

[connecticcut]

Add cyan developer.
before discarding the old IU I get the developer and I keep it in a ziplog.When I need the developer( cyan, magenta or yellow) I added in the corresponding UI (using the opening for the passage of toner )

same developper for differents modeles...

[Stirton.M]

Add cyan developer.
before discarding the old IU I get the developer and I keep it in a ziplog.When I need the developer( cyan, magenta or yellow) I added in the corresponding UI (using the opening for the passage of toner )

same developper for differents modeles...

This is actually not a bad idea....there are times when the dev unit has certainly dumped its contents, though I suspect that this method is a time consuming endeavor...pour some in to fill the end area, push it in to auger the content, test output...repeat until even coverage...I'll have to try that...though I am a bit gun shy about carrying glad bags of developer in my car...I had one explode in my trunk one day, from a hard stop I had to do if I recall, the tool kit rammed into the box of minor supplies I had near the front end of the trunk....try as I did, I never did get all of it cleaned up before I got rid of it. The new car, well....that kind of mess would be a nightmare to say the least....

[Hansoon]

the cause of this was crappy aftermarket toner.

Would you share with us the name of that aftermarket toner please?

Hans