Bizhub C451 Black Developer

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  • Dave10
    Trusted Tech

    100+ Posts
    • Jul 2008
    • 197

    #1

    Bizhub C451 Black Developer

    About 6 months ago a customer called with black background on copies. When I pulled out the black I.U., it had developer all over the top of the drum and down into the machine. It was pulling developer out of the unit and dumping it into the machine. Did an EXTENSIVE clean-up and was told to replace the developer bias high voltage board and the black unit. A few weeks ago,the customer called back with background. I could not repeat the problem, but found a small amount of developer on top of the drum. Called Tech Support and was told some developer is normal and don't worry about it. Today, we were called back and discovered the same problem as before, tons of developer pulled out and a huge mess. Anyone have other suggestions?
  • Albonline
    Service Manager

    1,000+ Posts
    • Sep 2008
    • 1131

    #2
    I know this sounds crazy but replace the print head unit. we have had 4 machines pull developer, the first2 drove me nuts trying to fix then i said what the hell try the ph and it fixed them.doesent make any sense but hey.

    Comment

    • KEVIN900
      Copier Ninja

      100+ Posts
      • Oct 2009
      • 200

      #3
      I believe that you replace all 4 laser units as a set. And, Konica Minolta has acknowledged a manufacturing defect with these print heads, so have your parts guy check into getting a full set on exchange. Won't cost your company anything but time. Good luck.
      Kevin900

      Comment

      • Stirton.M
        All things Konica Minolta

        1,000+ Posts
        • Oct 2009
        • 1804

        #4
        Originally posted by Dave10
        About 6 months ago a customer called with black background on copies. When I pulled out the black I.U., it had developer all over the top of the drum and down into the machine. It was pulling developer out of the unit and dumping it into the machine. Did an EXTENSIVE clean-up and was told to replace the developer bias high voltage board and the black unit. A few weeks ago,the customer called back with background. I could not repeat the problem, but found a small amount of developer on top of the drum. Called Tech Support and was told some developer is normal and don't worry about it. Today, we were called back and discovered the same problem as before, tons of developer pulled out and a huge mess. Anyone have other suggestions?

        When this problem occurs, developer bias is not being maintained and the developer tends to do as you are observing. When properly operating, the developer and drum both have a strong negative charge applied to them. The drum gets this by localized induction via charge corona. When both units are at the same potential, no toner will be drawn to the drum. The laser unit will shine a laser light onto the drum, causing a discharge where it writes to. The discharged areas are more positive relative to the developer. This draws toner from the developer onto the drum surface where the laser wrote. If for some reason the drum no longer gets a negative charge it needs initially, it can become too positive relative to the developer and will physically pull the developer material along with the toner out. If it is excessive and builds up before the drum unit rolls around and cleans excess toner (a normal operation), this starter will literally ground the drum unit to the body of the developer unit. Once it starts, a cascade effect happens and it gradually gets worse and worse until the developer does as you were observing.

        HV1 is typically the item that fails, and this problem is related in a TSB. It is recommended to replace HV1. Also, sometimes this can happen if the image unit is not properly seated and locked in place. Those lock tabs tend to be a bit finicky and can release, allowing the IU to drift towards the front of the machine, and developer bias loses physical connection at the back end. Check the back side while the image unit unit is out to look for possible damage to the bias connect points inside the machine as well as the dev unit itself.

        Though the TSB does not show what you saw as an aftermath, it relates what you should have seen leading up to it.

        Solution ID
        TAUS0900963EN*

        Description
        Copies and prints are grainy and black developer is on the copies.
        Solution
        CAUSE: HV1 has failed.
        SOLUTION: Replace HV1 (p/n A00J M407 01).
        SPECIAL NOTE : Solution contribution by Mark D'Attilio, Production Print/SSD
        "Many years ago I chased a woman for almost two years, only to discover that her tastes were exactly like mine: we both were crazy about girls."
        ---Groucho Marx


        Please do not PM me for questions related to Konica Minolta hardware.
        I will not answer requests or questions there.
        Please ask in the KM forum for the benefit of others to see the question and give their input.

        Comment

        • alexfixes
          Technician
          50+ Posts
          • Jan 2010
          • 68

          #5
          replace the IU again and HV1

          Originally posted by Dave10
          About 6 months ago a customer called with black background on copies. When I pulled out the black I.U., it had developer all over the top of the drum and down into the machine. It was pulling developer out of the unit and dumping it into the machine. Did an EXTENSIVE clean-up and was told to replace the developer bias high voltage board and the black unit. A few weeks ago,the customer called back with background. I could not repeat the problem, but found a small amount of developer on top of the drum. Called Tech Support and was told some developer is normal and don't worry about it. Today, we were called back and discovered the same problem as before, tons of developer pulled out and a huge mess. Anyone have other suggestions?
          I had some experience on that machine while I was with konica minolta working as a field tech and I had same issue with adifferent model , I repalced the IU and fixed the problem . I would also check the setting on bias voltage and make sure is set to factory default, lot of time these seeting get changed by other techs . I was actually laid off from konica minolta in CA last year. good luck

          Comment

          • kmcopier
            PSP

            100+ Posts
            • Oct 2008
            • 183

            #6
            There is a technical info about this for the imaging unit, the unit is modified from april 2009 check your lotno:, If the unit is before you can modify it your self how is also in the TNI....

            Comment

            • alexfixes
              Technician
              50+ Posts
              • Jan 2010
              • 68

              #7
              di470 ftp scan

              need help on di470 ftp scan setup on vin2003 server. I configured the copier for ftp site,also webed in to the di470 from server and under scan setup configured the ip address, distination name, and shared folder is configured on server for full access, but I only need to enter the directery name on the box. anybody have any idea what to put in there.
              the directory where they scan is on f:\ScanShare. when I'm scanning to folder can't find distination. thnaks for your help.

              Comment

              • B0265
                Senior Tech

                500+ Posts
                • Jan 2007
                • 718

                #8
                Originally posted by kmcopier
                There is a technical info about this for the imaging unit, the unit is modified from april 2009 check your lotno:, If the unit is before you can modify it your self how is also in the TNI....
                I have not found this TNI, can you upload it here?

                Comment

                • Dave10
                  Trusted Tech

                  100+ Posts
                  • Jul 2008
                  • 197

                  #9
                  Thanks for all the info. Sounds like we're replacing the board AGAIN. However, we service these machines under the NEC brand, and we are not Konica dealers. As such, we have no access to the KM bulletins. Could someone please post TAUS0900963. We are authorized by NEC, but they have not posted this bulletin.
                  I have some questions. Does the HV1 board go bad, and if so, why is it only the black IU that does this? Why don't the color units do this? Is anyone aware of any way to adjust the latching for the black unit to be sure it stays in firm contact?

                  Comment

                  • alexfixes
                    Technician
                    50+ Posts
                    • Jan 2010
                    • 68

                    #10
                    HV1 on c450

                    Originally posted by Dave10
                    Thanks for all the info. Sounds like we're replacing the board AGAIN. However, we service these machines under the NEC brand, and we are not Konica dealers. As such, we have no access to the KM bulletins. Could someone please post TAUS0900963. We are authorized by NEC, but they have not posted this bulletin.
                    I have some questions. Does the HV1 board go bad, and if so, why is it only the black IU that does this? Why don't the color units do this? Is anyone aware of any way to adjust the latching for the black unit to be sure it stays in firm contact?
                    yes sir, to answer your question on hV1, usaully HV1 produces charge to your image transfer roller and when it failes it does not produce charge,you can check if your imgae tranfer roller failes on state confirm, level history2,ATVC and it should be above 1000. part# HV1 4037620101. konica site dont have servcie manuals and you have to request that. I'm konica certified and have access to the knowledgebase. some toner dump on black IU are normal and sometimes you just have to make sure he copy quality is good. if you have clean copy i really wouldn't wory too much about changing adjustments and settings,just maintaining the machine and do the p/m. good luck
                    Last edited by alexfixes; 01-07-2010, 06:51 PM. Reason: error

                    Comment

                    • alexfixes
                      Technician
                      50+ Posts
                      • Jan 2010
                      • 68

                      #11
                      HV1 on c451

                      Originally posted by alexfixes
                      yes sir, to answer your question on hV1, usaully HV1 produces charge to your image transfer roller and when it failes it does not produce charge,you can check if your imgae tranfer roller failes on state confirm, level history2,ATVC and it should be above 1000. part# HV1 4037620101. konica site dont have servcie manuals and you have to request that. I'm konica certified and have access to the knowledgebase. some toner dump on black IU are normal and sometimes you just have to make sure he copy quality is good. if you have clean copy i really wouldn't wory too much about changing adjustments and settings,just maintaining the machine and do the p/m. good luck
                      Also HV1 , HV2 have cascade failure and HV1 is typically the item that fails becasue of TSB. If the Image unit also not properly in place will cause that problem.

                      Comment

                      • Dave10
                        Trusted Tech

                        100+ Posts
                        • Jul 2008
                        • 197

                        #12
                        We just replaced HV1 and brought the machine up and made 100+ black copies with no problems, but when making multiple color copies, we have what looks like a repeated image on the lead edge of the copies. The image looks like a light and smudged repeat of the pattern from earlier copies. Any ideas?

                        Comment

                        • alexfixes
                          Technician
                          50+ Posts
                          • Jan 2010
                          • 68

                          #13
                          need sample of the issue

                          Originally posted by Dave10
                          We just replaced HV1 and brought the machine up and made 100+ black copies with no problems, but when making multiple color copies, we have what looks like a repeated image on the lead edge of the copies. The image looks like a light and smudged repeat of the pattern from earlier copies. Any ideas?
                          hi, I like to see the sample of the problem that you have.
                          usally on tech rep i run stibilizationa nd inilization first. i run this maybe 2 times, you want to also make sure gradiation is acurate and fine, do gruiation, then i would go to half tone and cahnge the setting for 99, usally the default is 255 then you can really see half tone for each color should be lighter when reunning it at 99. this test usally tells you which color is giving you problem.
                          this has fixed many prblems specially with doule image and color smuged.
                          the half tone seeting will go back to deafult of 255 when powering off or going out of the tech rep.
                          I still want to see the sample.
                          good luck

                          Comment

                          • Dave10
                            Trusted Tech

                            100+ Posts
                            • Jul 2008
                            • 197

                            #14
                            The sample is attached, I hope. Any advice?
                            Attached Files

                            Comment

                            • alexfixes
                              Technician
                              50+ Posts
                              • Jan 2010
                              • 68

                              #15
                              sample recieved

                              Originally posted by Dave10
                              The sample is attached, I hope. Any advice?
                              I saw the sample, the only time I seen this issue is when the fuser unit was faulty. this is someting like oily stuff on the paper. never seen this before.
                              but thoes adjustment that i just mentioned will help to isolate the problems.I usally go to tech rep and do graduation first, then i run stibilization few imes, after that you need to run half tone test and change the adjustmet to 99 and check for each color and print the page, it prints solid color for c,k,y,m and the color is light because the half tone is change from 255 to 99. try and see if you have same issue.
                              I try to get some mor info for you. make sure your paper size also is set correct for the tickness, if it's glossy or regular, there are mny issues with selecting correct size.

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