CS-400ci - hundreds of random black dots background on copies

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  • WIL
    • Jun 2025
    #1

    [CQ] CS-400ci - hundreds of random black dots background on copies

    INSTALLED NEW UPGRADED BLACK DEVELOPER UNIT (TECH BULLETIN 12) DUE TO CONTINUING BLACK SMUDGES AND BACKGROUND OF TINY BLACK DOTS FOR THE LAST 6 MONTHS. (COPY COUNT 160K)

    THEN CUSTOMER DID A LONG BLACK & WHITE COPY JOB AND COPIES NOW APPEAR OVERTONED, AND HAVE THE DOT BACKGROUND AS STATED EARILIER.

    HAVE GONE THRU THE 500ci SERIES TROUBLESHOOTING GUIDE AND SPOKEN TO THE HOTLINE, BUT KEEP HAVING PROBLEMS OVER & OVER.

    DO THE ADJUSTMENTS IN THE TROUBLESHOOTING GUIDE EVEN APPLY TO THIS NEW BLACK DEV UNIT?

    MONDAY MORNING, I AM GOING TO USE THE ADJUSTMENT LIST PROVIDED BY BLACKCAT ON THE CS-400ci AC CALIBRATION THREAD ABOUT 2 WEEKS AGO IN THIS FORUM.

    I WILL APPRECIATE ANY OTHER SUGGESTIONS
    Tags: black, copies, copy, copy count, count, customer, developer, developer unit, dirty, job, tech, unit
    • blackcat4866
      Master Of The Obvious

      Site Contributor
      10,000+ Posts
      • Jul 2007
      • 22999
      #2
      Re: CS-400ci - hundreds of random black dots background on copies

      Are we talking about the infamous donut dots, which are not random, they're just difficult to identify the pattern at 96.75mm intervals? Those are caused by the drum of the appropriate color. It looks like overtoning, but in reality is pinholes in the drum surface. The best way to demonstrate the donut dots is to print a half-tone page at 50% fill on ledger size paper in the appropriate single color to emphasize the dots, then with the help of a ruler pick out the pattern. All the drum units are identical, so you can swap two drums to help identify the issue.

      To check for overtoning you can go to simulation U131, and check that the values in the right column are within 25 points of the reference values in the left column. You can try to improve those values by running a developer refresh in the System Menu > Adjustments/Maintenance.

      Whenever you see Kyocera color machines it's a good idea to run through those adjustments. The only situation where I wouldn't is if I was just returning with a non-quality related part (like a set of feed tires or cover) and it had only been a couple days since it was done last. =^..^=
      If you'd like a serious answer to your request:
      1) demonstrate that you've read the manual
      2) demonstrate that you made some attempt to fix it.
      3) if you're going to ask about jams include the jam code.
      4) if you're going to ask about an error code include the error code.
      5) You are the person onsite. Only you can make observations.

      blackcat: Master Of The Obvious =^..^=

        Comment

        • WIL
          #3
          Re: CS-400ci - hundreds of random black dots background on copies

          Thank you, Blackcat!

          The black dots, at least the ones i could measure due to their recognizable patterns, are 96 mm apart. So, it is the drum causing that. The apparent overtoning may be a separate issue, so i'll look at that tomorrow.


          Thanks again,


          Wil

            Comment

            • tmaged
              Owner/Service Manager

              Site Contributor
              1,000+ Posts
              • Oct 2008
              • 1869
              #4
              Re: CS-400ci - hundreds of random black dots background on copies

              Wil, it's the charge roller for the drum unit causing those little arcing burn marks in the drum. They've changed outer
              cover on the new ones.
              Hope that helps !
              -Tony
              www.dtios.com
              Become a fan on Facebook

                Comment

                • ru4real
                  Technician
                  • Aug 2011
                  • 13
                  #5
                  Re: CS-400ci - hundreds of random black dots background on copies

                  Wil,

                  Agreed about the charge roller being the cause of the problem. Had my service rep with me several weeks back for 2 machines with spots all over the page (cyan, magenta). 126,345 clicks on the machine. We replaced the whole drum assemblies (under warranty) and ran through the 500ci tech bulletin for the ac calibration. So far so good, checked back with the account and everything is running well at this point.

                  Good Luck,

                    Comment

                    • marc
                      Technician

                      50+ Posts
                      • Feb 2010
                      • 56
                      #6
                      Re: CS-400ci - hundreds of random black dots background on copies

                      Sometimes you don't need to replace the drum the only that you need is clean every drum with "D" ink dry with a clean microfiber I know that you can't use any liquid to clean these drums but for me is been working ok for the las 12 moths after i cleaned the quality is much better the other way swap the drum to see which one is the dirty drum, good luck.

                        Comment

                        • blackcat4866
                          Master Of The Obvious

                          Site Contributor
                          10,000+ Posts
                          • Jul 2007
                          • 22999
                          #7
                          Re: CS-400ci - hundreds of random black dots background on copies

                          I've haven't had much luck with cleaning those drums. The pinholes may not be visible to the naked eye, but they are flaws in the drum surface. If I were a betting man, I'd be betting on them coming back. =^..^=
                          If you'd like a serious answer to your request:
                          1) demonstrate that you've read the manual
                          2) demonstrate that you made some attempt to fix it.
                          3) if you're going to ask about jams include the jam code.
                          4) if you're going to ask about an error code include the error code.
                          5) You are the person onsite. Only you can make observations.

                          blackcat: Master Of The Obvious =^..^=

                            Comment

                            • Metalvoc
                              Trusted Tech

                              100+ Posts
                              • Sep 2008
                              • 155
                              #8
                              Re: CS-400ci - hundreds of random black dots background on copies

                              I have had no luck cleaning drums, either. replaced a lot of them! This problem started with F/W ver. 10 or 11. F/W 12 specifically claims to resolve the drum dot issue. So make sure you get your taskalfas upgraded to 12 ASAP!
                              I must have a prodigious quantity of mind; it takes me as much as a week sometimes to make it up - Mark Twain

                                Comment

                                • WIL
                                  #9
                                  Re: CS-400ci - hundreds of random black dots background on copies

                                  Sorry I have taken so long in following up.

                                  What I discovered on my 400ci was white dust (? - paper dust, I assume) coating all four drums and all four charge rollers.

                                  To fix, I merely dry wiped the drums and rollers! -- Copies were perfect after that. We'll see how long that lasts.

                                  The question is, how did paper dust get all the way up inside there? My customer is not using cheap paper.

                                  Thanks for all the great responses to my problem.

                                  Wil

                                    Comment

                                    • blackcat4866
                                      Master Of The Obvious

                                      Site Contributor
                                      10,000+ Posts
                                      • Jul 2007
                                      • 22999
                                      #10
                                      Re: CS-400ci - hundreds of random black dots background on copies

                                      you'll be baaaack. =^..^=
                                      If you'd like a serious answer to your request:
                                      1) demonstrate that you've read the manual
                                      2) demonstrate that you made some attempt to fix it.
                                      3) if you're going to ask about jams include the jam code.
                                      4) if you're going to ask about an error code include the error code.
                                      5) You are the person onsite. Only you can make observations.

                                      blackcat: Master Of The Obvious =^..^=

                                        Comment

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