bizhub 421 - grey backround only when printing double-sided (after about 500 prints)

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  • Laserbeam
    Trusted Tech

    100+ Posts
    • Aug 2011
    • 152
    #1

    [CQ] bizhub 421 - grey backround only when printing double-sided (after about 500 prints)

    Hello at all,

    a bizhub 421 in a copy-shop shows following symptom:

    Only when print double-sided, after approximately 500 sheets, one side shows grey backround. The other side is perfect. The backround-side in the paper-tray from the finisher points towards the floor (It would be the second printed page, isn't it or I'm thinking wrong?).
    If the machine stands still for a longer time, the first double-sided prints are back in order. Then the problem starts again anew.

    Single-sided printing makes no gray background.

    Life Counter: Drum 130k, Developer 70k

    My first action was to clean all ground-contacts from the charging- and transver/sep. corona, drum- and developing unit, ground-contacts in the right side-door, etc., but unfortunately without success!!!
    In my opinion it would be a potential-problem, not an overtoning-problem. Otherwise, the other side would be gray, too.

    Yesterday I got a call from the owner of the copy shop, the neighbour-machine, a bizhub 501, now has exactly the same problem!!!!
    This problem might be a weak point of this series of KM????

    Greetings from (C)Old-Germany
    Tags: None
    • Synaux
      Service Manager

      Site Contributor
      1,000+ Posts
      • Mar 2012
      • 1224
      #2
      Re: bizhub 421 - grey backround only when printing double-sided (after about 500 prin

      Originally posted by Laserbeam
      Hello at all,

      a bizhub 421 in a copy-shop shows following symptom:

      Only when print double-sided, after approximately 500 sheets, one side shows grey backround. The other side is perfect. The backround-side in the paper-tray from the finisher points towards the floor (It would be the second printed page, isn't it or I'm thinking wrong?).
      If the machine stands still for a longer time, the first double-sided prints are back in order. Then the problem starts again anew.

      Single-sided printing makes no gray background.

      Life Counter: Drum 130k, Developer 70k

      My first action was to clean all ground-contacts from the charging- and transver/sep. corona, drum- and developing unit, ground-contacts in the right side-door, etc., but unfortunately without success!!!
      In my opinion it would be a potential-problem, not an overtoning-problem. Otherwise, the other side would be gray, too.

      Yesterday I got a call from the owner of the copy shop, the neighbour-machine, a bizhub 501, now has exactly the same problem!!!!
      This problem might be a weak point of this series of KM????

      Greetings from (C)Old-Germany
      Is the power good? Are they on line conditioners??
      Remember the first side is the second sided image.

      This might give you some ideas:

      TAUS0703844EN*
      Description
      C2801 (C-2801) code possibly accompanied by agray background on copies.
      Solution
      PROBABLE CAUSES:
      1. The HVPS has failed.
      Replace the HVPS (p/n 50GA84010). [appears to be the same for both the 421 and 501.]
      SPECIAL NOTE : Solution contribution by Tom Kelly, Workgroup/SSD

      2.A TCR output abnormality; the TCR output is in excess of 3.0V DC. This is usually due to a severe undertoning or a failed TCR sensor. It is possible to run
      the Toner Auto Condition mode under the Service Mode =>Image Adjust Mode. Running this setting will automatically add toner to the developer if
      depleted. If the Auto Toner Condition mode fails to correct the issue, the developer and the TCR sensor should be replaced.
      Replace thedeveloper and TCR sensor (p/n 26NA-8804-1).Be sure to reference the attached Field Service Manual pagesand perform all adjustments
      associated with developer replacement.

        Comment

        • EarthKmTech
          Step aside, noob

          1,000+ Posts
          • May 2009
          • 2142
          #3
          Re: bizhub 421 - grey backround only when printing double-sided (after about 500 prin

          ive had this many times ever since the first 420/500 machines came out and only ever changed the developer to solve the problem.

          If the customer is using bad paper that ends up shedding a lot of paper dust it will not last the 250k service cycle. I dont know how or why but it has always been the second side that starts to show the problem first.

            Comment

            • Laserbeam
              Trusted Tech

              100+ Posts
              • Aug 2011
              • 152
              #4
              Re: bizhub 421 - grey backround only when printing double-sided (after about 500 prin

              Last week I changed the developer with an new one and all was fine !! The customer prints several hundred double-sided pages and no toner-backround occurs.

              But today he called me again, because the old problem returns again .


              I think it's a problem of this model, which can not be solved with simple methods. I think it's best if we replace the machines.

                Comment

                • allan
                  RTFM!!

                  5,000+ Posts
                  • Apr 2010
                  • 5445
                  #5
                  Re: bizhub 421 - grey backround only when printing double-sided (after about 500 prin

                  Try changing the developer unit.

                  The charge and grid voltage could be tampered with.

                  Do you use the list of adjustment items if you replace the developer?

                  Did you reset the drum counter after replacing the drum?
                  Whatever

                    Comment

                    • Laserbeam
                      Trusted Tech

                      100+ Posts
                      • Aug 2011
                      • 152
                      #6
                      Re: bizhub 421 - grey backround only when printing double-sided (after about 500 prin

                      Hello allan,

                      thank you for your quick response!
                      Our company used for this machine toner from Katun, no original toner. Could this be the reason for this problem?
                      When I replaced the developer, I only performed the TCR adjustment.

                      This week I will start a last attempt with exchange of the following components:

                      1. Drum and Blade-unit
                      2. Developer and Developer-unit (Dev.-unit from a used machine with a total count about 130K)
                      3. Charging- and Transfer/Sep. Corona unit (both have a duration of about one million)

                      Then I will perform the following adjustments:

                      1. TCR
                      2. Toner density
                      3. Laser diameter
                      4. LD1 Offset
                      5. LD2 Offset

                      I hope this will fix the problem, otherwise I have no other idea.

                        Comment

                        • blackcat4866
                          Master Of The Obvious

                          Site Contributor
                          10,000+ Posts
                          • Jul 2007
                          • 22743
                          #7
                          Re: bizhub 421 - grey backround only when printing double-sided (after about 500 prin

                          Originally posted by Laserbeam
                          Hello allan,

                          thank you for your quick response!
                          Our company used for this machine toner from Katun, no original toner. Could this be the reason for this problem?
                          When I replaced the developer, I only performed the TCR adjustment.

                          This week I will start a last attempt with exchange of the following components:

                          1. Drum and Blade-unit
                          2. Developer and Developer-unit (Dev.-unit from a used machine with a total count about 130K)
                          3. Charging- and Transfer/Sep. Corona unit (both have a duration of about one million)

                          Then I will perform the following adjustments:

                          1. TCR
                          2. Toner density
                          3. Laser diameter
                          4. LD1 Offset
                          5. LD2 Offset

                          I hope this will fix the problem, otherwise I have no other idea.
                          Oh yes! Look no further. Change to OEM if you care about the image quality. =^..^=
                          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

                            • Laserbeam
                              Trusted Tech

                              100+ Posts
                              • Aug 2011
                              • 152
                              #8
                              Re: bizhub 421 - grey backround only when printing double-sided (after about 500 prin

                              Hello blackcat 4866,

                              thankyou for your response!

                              At first I will vacuum all Katun-Toner and replace it with original one.

                                Comment

                                • blackcat4866
                                  Master Of The Obvious

                                  Site Contributor
                                  10,000+ Posts
                                  • Jul 2007
                                  • 22743
                                  #9
                                  Re: bizhub 421 - grey backround only when printing double-sided (after about 500 prin

                                  Originally posted by Laserbeam
                                  Hello blackcat 4866,

                                  thankyou for your response!

                                  At first I will vacuum all Katun-Toner and replace it with original one.
                                  It will take some time to consume the remaining Katun toner from the developer mix. It should only take a few days to consume it and replenish with OEM. Copy quality will gradually improve. =^..^=
                                  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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