Black to color conversion - use of black pcu

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  • Mark Bbb
    Service Manager

    1,000+ Posts
    • Jun 2012
    • 1662
    #1

    Black to color conversion - use of black pcu

    Hoi,
    For testing a black pcu for a worn surface (mpc3002 - black dots) I make a copy with black conversion to cyan setting.
    Black dots are also appearing on this conversion copy (so i know black PCU is worn).
    So, it seems that the black pcu is still involved in this conversion process...
    Isn't there a sort of grayscale for each color?
    Or is this grayscale made together with the black pcu?
    Tags: black, conversion, copy, grayscale, pcu
    • Gift
      Service Manager

      1,000+ Posts
      • Mar 2011
      • 2413
      #2
      Re: Black to color conversion - use of black pcu

      Don't really get your question here but if you see black spots in a repeating pattern mathing the drum diameter (large format test) while testing in black/white mode it's 100% the black drum since cmy drums aren't involved in that mode.

        Comment

        • Polarbear
          Service Manager

          1,000+ Posts
          • Feb 2012
          • 1070
          #3
          Re: Black to color conversion - use of black pcu

          Originally posted by Mark Bbb
          Hoi,
          For testing a black pcu for a worn surface (mpc3002 - black dots) I make a copy with black conversion to cyan setting.
          Black dots are also appearing on this conversion copy (so i know black PCU is worn).
          So, it seems that the black pcu is still involved in this conversion process...
          Isn't there a sort of grayscale for each color?
          Or is this grayscale made together with the black pcu?
          You could access COPY Sp mode and select SP5618. Change the value to 0. Exit SP mode.
          You will see you now have a single color button to select and be able to do selsctive single colour copies.

          But like Gift said, if the marks match the diameter of the drum, it is 100% given that it is the cause.

          The reason why black marks may appear in colour copies, is because the machine uses black to make any given colour darker.

          Hope that makes sense.
          Press the GREEN button!!

            Comment

            • Mark Bbb
              Service Manager

              1,000+ Posts
              • Jun 2012
              • 1662
              #4
              Re: Black to color conversion - use of black pcu

              Originally posted by Polarbear
              You could access COPY Sp mode and select SP5618. Change the value to 0. Exit SP mode.
              You will see you now have a single color button to select and be able to do selsctive single colour copies.

              But like Gift said, if the marks match the diameter of the drum, it is 100% given that it is the cause.

              The reason why black marks may appear in colour copies, is because the machine uses black to make any given colour darker.

              Hope that makes sense.
              Strange that colour don't use grayscale but the black drum for darkening...
              That's what i wanted to know, thanks.

                Comment

                • TonerMunkeh
                  Professional Moron

                  2,500+ Posts
                  • Apr 2008
                  • 3873
                  #5
                  Re: Black to color conversion - use of black pcu

                  This caught me out not long after I started working on the Apollon / Athena. The black drum is always in contact with the ITB so any marks on the black will show even if black isn't being used.
                  It's 106 miles to Chicago. We've got a full tank of gas, half a pack of cigarettes, it's dark and we're wearing sunglasses.

                  Hit it.

                    Comment

                    • fshead
                      Service Manager

                      1,000+ Posts
                      • Jan 2009
                      • 2356
                      #6
                      Re: Black to color conversion - use of black pcu

                      Originally posted by Mark Bbb
                      Hoi,For testing a black pcu for a worn surface (mpc3002 - black dots) I make a copy with black conversion to cyan setting.Black dots are also appearing on this conversion copy (so i know black PCU is worn).So, it seems that the black pcu is still involved in this conversion process...Isn't there a sort of grayscale for each color?Or is this grayscale made together with the black pcu?
                      i have seen a few mpc3002 drums wear early because of bad after market toner..Like it was not fine and caused it wear down...

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