Canon np 6545 blank copies

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  • blazebusiness
    SanDiegoCopierRepair.com

    Site Contributor
    1,000+ Posts
    • Apr 2010
    • 1250
    #1

    Canon np 6545 blank copies

    Old copier with a lot of clicks has blank copies. Once in a while but very infrequently when you power off the copier and turn it back on you may get 1 copy. And then reverts to blank copies again. One of my techs has Swapped out the following from a working model- coronas....potential control assy....lamp regulator pcb....entire drum unit....varistor.....dc controller......dv unit.....hvt.....pot control pcb assy etc...

    I,m about to take over the call and go there myself. Any ideas much appreciated. For starters im thinking xfer corona connecter grounding out or something of that nature.
    sigpicAnything can be made to work if you fiddle with it long enough- San Diego Copier Repair.com
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    • Rachid.Akli
      Senior Tech

      500+ Posts
      • Oct 2011
      • 595
      #2
      Re: Canon np 6545 blank copies

      In these models (analog copiers with potential control) when the scanning lamp doesn't light, you will get a blank copy because the DC bias will be at its maximum value and toner will not be able to go to the drum (no developement).By the way, what are the values of Vdm and VLm in display mode.Rachid.
      "Find a job you love and you’ll never have to work a day in your life." Nagy's father

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        • blazebusiness
          SanDiegoCopierRepair.com

          Site Contributor
          1,000+ Posts
          • Apr 2010
          • 1250
          #3
          Re: Canon np 6545 blank copies

          Originally posted by Rachid.Akli
          In these models (analog copiers with potential control) when the scanning lamp doesn't light, you will get a blank copy because the DC bias will be at its maximum value and toner will not be able to go to the drum (no developement).By the way, what are the values of Vdm and VLm in display mode.Rachid.
          Thanks for replying - Scan lamp has already been replaced by my tech and lights up fine. I inspected the reflector to make sure it was ok after his work on the scan lamp. Vdm - 453v , VL1M - 173v , VL2M - 153v. I'm thinking maybe the connector in the back of the machine behind the xfer corona or the high voltage cables from the hvt or wiring. Some times if you manually darken the copies a super faint image appears to be visible but most the time not even darkening it will make an image. Sometimes after power is cycled you may get 1 copy before blank copies start but most of the time even cycling power has no effect.
          sigpicAnything can be made to work if you fiddle with it long enough- San Diego Copier Repair.com

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            • Rachid.Akli
              Senior Tech

              500+ Posts
              • Oct 2011
              • 595
              #4
              Re: Canon np 6545 blank copies

              Try to replace the developing cylinder cluch CL8. and verify its rotation.

              The pretranster corona (if not replaced) can create a short-circuit and results in zero transfert current.

              Rachid
              "Find a job you love and you’ll never have to work a day in your life." Nagy's father

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                • blazebusiness
                  SanDiegoCopierRepair.com

                  Site Contributor
                  1,000+ Posts
                  • Apr 2010
                  • 1250
                  #5
                  Re: Canon np 6545 blank copies

                  Originally posted by Rachid.Akli
                  Try to replace the developing cylinder cluch CL8. and verify its rotation.

                  The pretranster corona (if not replaced) can create a short-circuit and results in zero transfert current.

                  Rachid
                  Sounds like you and i think just alike. Already tried all that and ran copier without the prexfer corona. Next i,m gonna check the ms5 microswitch. I seem to remember that can cause this as well.
                  sigpicAnything can be made to work if you fiddle with it long enough- San Diego Copier Repair.com

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                    • Herrmann
                      Senior Tech

                      Site Contributor
                      500+ Posts
                      • Jan 2006
                      • 792
                      #6
                      Re: Canon np 6545 blank copies

                      did you try to disable the potential control via service mode? does the image change? open the door while making sky copies, how do the drum surface look like?
                      If sometimes you feel a little useless, offended and depressed always remember that you were once the fastest and most victorious sperm of hundreds of millions!

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                        • oldschool
                          Trusted Tech

                          100+ Posts
                          • Mar 2007
                          • 245
                          #7
                          Re: Canon np 6545 blank copies

                          I remember working on a NP Canon that had a problem like this. Memory is fuzzy but I seem to remember this copier had a corona socket that had a hairline crack in it. Caused HVT output to be grounded out and shut down.
                          Another odd thing I remember causing blank copies with Canons.
                          HVT did not have a good ground.
                          Jamex Tech Support: Saving the world one phone call at a time.

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                            • blazebusiness
                              SanDiegoCopierRepair.com

                              Site Contributor
                              1,000+ Posts
                              • Apr 2010
                              • 1250
                              #8
                              Re: Canon np 6545 blank copies

                              Originally posted by Herrmann
                              did you try to disable the potential control via service mode? does the image change? open the door while making sky copies, how do the drum surface look like?
                              Yes disabled potential control in service mode with no change in problem. So that makes me want to look at the connector that the xfer corona plugs into (what oldschool calls socket) or hv cables or the microswitch. Will let you guys know what fixes it and thanks very much for all the replies.
                              sigpicAnything can be made to work if you fiddle with it long enough- San Diego Copier Repair.com

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                                • irtek
                                  Trusted Tech

                                  100+ Posts
                                  • Jun 2009
                                  • 109
                                  #9
                                  Re: Canon np 6545 blank copies

                                  I would be looking more towards the Primary charge instead of transfer. Most of the time on Canons even if you lost transfer you would get a faint image from the paper hitting the drum. Most of the time if it was totally blank it would be Primary charge missing. Another thing to check is the drum drive. Had an NP8530 that a set screw came loose on the drum drive gear and had blank copies.

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