RP3700 Red Drum not fully inking up.

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  • ROTA
    • Jun 2025

    #1

    [Misc] RP3700 Red Drum not fully inking up.

    I've recently purchased an old RP3700 and while some drums work, this one unfortunately does not.

    I've attached images of the issue. I've tried cleaning the exterior screen with meths. Looking for other potential fixes. Two of the other drums i've received also have issues with not inking up or the ink having expired and seperated into clumpy goo. Black and Blue drums run fine so no issue with the machine as far as i can tell.

    Note: This photo is from after cleaning the exterior screen with solvent and attempting to run some confidentials.
    IMG_1571.jpg
  • Visirecord 101
    Junior Member
    • Jan 2015
    • 9

    #2
    Re: RP3700 Red Drum not fully inking up.

    Hate to tell you, but you probably have a messy cleaning job ahead... I have had similar issues although not as extreme. Most likely the metal screen and the outer screen are clogged up, but it is possible that there is an ink distribution issue within the drum. If it were my Riso I would remove the outer screen and buy a new one, they are available online. Then I would mark carefully the location of the metal screen on the outer ends of the drum and start removing the screws being very careful no to score or kink the screen. When you get a look inside, check to see if the ink is being distributed evenly by the interior rollers on the inside of the screen. If it is then remove the screen and use solvents to clean it. I find mineral spirits is strong enough without having all the issues of a very strong or toxic solvent. One of the heavy aluminum foil turkey roasting pans from the grocery store helps contain the mess. Have a roll of paper towels nearby.

    When you reattach the screen don't tighten the screws all the way until you have the screen in the correct position at least half way around. I've just used good old blue tape to replace the factory tape where the ends of the screen meet, with no problems. Having a second drum handy is a great help in relocating the screen.

    If the ink within the drum is really dried up the job gets a lot more complicated as the distribution manifold and ink pump may be clogged be as well... but if ink has been flowing when you tested it that wont be a problem.. Be careful not break off the thin wires protruding form a pc board into the ink on the rollers. That measures the ink level and turns the pump on and off. Good Luck!

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    • ROTA

      #3
      Re: RP3700 Red Drum not fully inking up.

      Brilliant, thanks for the instructions, will report back after a deep clean!

      Comment

      • ROTA

        #4
        Re: RP3700 Red Drum not fully inking up.

        After a complete teardown and thorough cleaning + new outer screen. Its doing the same thing :/ Images below. I'm guessing this is an issue with the internal roller? I'll pull it apart again and take photos.

        IMG_1890.jpg

        Comment

        • ROTA

          #5
          Re: RP3700 Red Drum not fully inking up.

          Sorry for the triple post. I'd delete or edit my previous posts if i could :/

          Heres a photo showing the internal roller of the drum, it seems the ink is making its way through the pump etc. perfectly well, but isnt spreading across the roller at all. Any ideas why this might be?

          Any help greatly appreciated.

          IMG_1895.jpgIMG_1894.jpgIMG_1893.jpgIMG_1891.jpg

          Comment

          • VENRISO
            Technician

            Site Contributor
            50+ Posts
            • Jul 2015
            • 72

            #6
            Re: RP3700 Red Drum not fully inking up.

            hi change de o ring in the nose ink pump and clean the ink filter in the ink pump

            Comment

            • 20gaugeO/U
              Senior Tech

              500+ Posts
              • Feb 2009
              • 553

              #7
              Re: RP3700 Red Drum not fully inking up.

              Yep clean the filter in the ink pump and everything out of the tubes that you can get to.

              What's the date stamped on the tube of ink? After doing all this work I'd probably start with a new tube, that ink looks thick in the pics

              Comment

              • mikadonovan
                Senior Tech

                Site Contributor
                2,500+ Posts
                • May 2008
                • 2931

                #8
                Re: RP3700 Red Drum not fully inking up.

                Originally posted by ROTA
                Sorry for the triple post. I'd delete or edit my previous posts if i could :/

                Heres a photo showing the internal roller of the drum, it seems the ink is making its way through the pump etc. perfectly well, but isnt spreading across the roller at all. Any ideas why this might be?

                Any help greatly appreciated.

                [ATTACH=CONFIG]35171[/ATTACH][ATTACH=CONFIG]35172[/ATTACH][ATTACH=CONFIG]35173[/ATTACH][ATTACH=CONFIG]35174[/ATTACH]
                See the thin metal ink probe at the right of the pcb in pic 2? That probe needs to be cleaned and adjusted so you have a 2mm bead of ink across the entire length of the roller.
                NEVER ASSUME ANYTHING

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