Help with Mystery -- Sudden changes in print densities Canon iR8500

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  • Juxta5
    Technician

    Site Contributor
    50+ Posts
    • Jul 2008
    • 65
    #1

    Help with Mystery -- Sudden changes in print densities Canon iR8500

    Was performing PM and strung new wires: Primary, secondary, separation and transfer. Did not replace array it has about 300,000 copies on it.

    I make a copy, it looks good but a bit light. Went through Image Adjustment Basic Procedure and made some very small adjustments to the wire heights. Make copies they look better.

    Make a few more copies, get a paper jam, clear the jam, then instantly copies are EXTREMELY light, barely visible.

    Turn machine off and on. Make copies they look fine again. Make about 50 copies and I notice they are slowly getting lighter. Another paper jam, clear the jam and instantly the copies are barely visible again.

    So I check VDM it's okay at 390, but VL1M reading was 290! And I'm thinking cool.. possibly Potential control. Turn off and check connections just to be safe. Turn back on and suddenly VL1M is normal at 77. and PG prints (4,5,6,7,8) look good.

    I also pulled the developing unit and the roller could use replacing. I'm not certain how old the develop unit is.

    So thoughts as to why the instant flip-flops between good image and super light images?
    Tags: density, developing unit, ir105, ir8500, potential control
    • Juxta5
      Technician

      Site Contributor
      50+ Posts
      • Jul 2008
      • 65
      #2
      Re: Help with Mystery -- Sudden changes in print densities Canon iR8500

      Oh, btw. No error codes with this one.

        Comment

        • teckat
          Field Supervisor

          Site Contributor
          10,000+ Posts
          • Jan 2010
          • 16083
          #3
          Re: Help with Mystery -- Sudden changes in print densities Canon iR8500

          Dev Bias_😱
          **Knowledge is time consuming, exhausting and costly for a trained Tech.**

            Comment

            • blackcat4866
              Master Of The Obvious

              Site Contributor
              10,000+ Posts
              • Jul 2007
              • 22930
              #4
              Re: Help with Mystery -- Sudden changes in print densities Canon iR8500

              Potential control can do this. You should be able to turn off potential control to use generic values, which should look much better temporarily. =^..^=
              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

                • Canuck
                  Tech Specialist

                  1,000+ Posts
                  • Nov 2007
                  • 1713
                  #5
                  Re: Help with Mystery -- Sudden changes in print densities Canon iR8500

                  Potential control is not done on the fly. Machine does it initially or when fuser cools down. Have you tried to replace the transfer/sep assembly? Check transfer current in service mode while it is running. Dev clutch slipping? HV leads?

                    Comment

                    • Juxta5
                      Technician

                      Site Contributor
                      50+ Posts
                      • Jul 2008
                      • 65
                      #6
                      Re: Help with Mystery -- Sudden changes in print densities Canon iR8500

                      Yes, developing unit.

                      When I tested this unit it could print single sided endlessly. In fact it printed 96,000 additional single sided sheets after my first post. But the minute it duplexed the image would become incredibly faint. I didn't make that connection when I first posted, ie that's why PG tests looked good.

                      I swapped out this machine's developing unit with a used spare and it can print both sides and maintain the density. But all said, it's best to retire this machine because parts are difficult to come by.

                      I get a sentimental over clean, well functioning machines and it's hard to let them go. This one was stellar, over 6 mil and if I could get parts... hell it just might double that.

                        Comment

                        • blackcat4866
                          Master Of The Obvious

                          Site Contributor
                          10,000+ Posts
                          • Jul 2007
                          • 22930
                          #7
                          Re: Help with Mystery -- Sudden changes in print densities Canon iR8500

                          Congratulations. =^..^=
                          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

                            • KenB
                              Geek Extraordinaire

                              2,500+ Posts
                              • Dec 2007
                              • 3945
                              #8
                              Re: Help with Mystery -- Sudden changes in print densities Canon iR8500

                              Glad it's working.

                              It's been years, but I got burned by slipping developer clutches and bound developer units enough times to look there first.

                              Also, it was more on the 8570, but some of the connectors on the DC controller were kinda touchy. I remember using a brass "toothbrush" and a can of spray contact cleaner to evict quite a few gremlins.
                              “I think you should treat good friends like a fine wine. That’s why I keep mine locked up in the basement.” - Tim Hawkins

                                Comment

                                • blackcat4866
                                  Master Of The Obvious

                                  Site Contributor
                                  10,000+ Posts
                                  • Jul 2007
                                  • 22930
                                  #9
                                  Re: Help with Mystery -- Sudden changes in print densities Canon iR8500

                                  Originally posted by KenB
                                  Glad it's working.

                                  It's been years, but I got burned by slipping developer clutches and bound developer units enough times to look there first.

                                  Also, it was more on the 8570, but some of the connectors on the DC controller were kinda touchy. I remember using a brass "toothbrush" and a can of spray contact cleaner to evict quite a few gremlins.
                                  Yeah, NP8530 and NP8570 were the last machines to use Ultrex connectors. I don't miss them a bit. =^..^=
                                  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

                                    • Canuck
                                      Tech Specialist

                                      1,000+ Posts
                                      • Nov 2007
                                      • 1713
                                      #10
                                      Re: Help with Mystery -- Sudden changes in print densities Canon iR8500

                                      Originally posted by blackcat4866
                                      Yeah, NP8530 and NP8570 were the last machines to use Ultrex connectors. I don't miss them a bit. =^..^=
                                      Really....Ultrex connectors....nightmares.....re-crimp....

                                        Comment

                                        • zoraldinho
                                          teacher-guide-expert-guru

                                          Site Contributor
                                          2,500+ Posts
                                          • Mar 2008
                                          • 4999
                                          #11
                                          Re: Help with Mystery -- Sudden changes in print densities Canon iR8500

                                          Ultrex connector related problems? Millions!
                                          If it ain't broke, don't fix it
                                          A picture is worth a thousand words

                                            Comment

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