MZ770 Riso master making error

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  • LizW
    • Jun 2025

    #1

    MZ770 Riso master making error

    Dear all, help needed; not urgent as managing to continue running with manual master removal [drum 1 only] but I would really like it resolved before issues start multiplying. I shall be as succinct as possible:

    Master was not feeding in master making unit some weeks ago.
    Thought it might be worn gear so pulled out and checked gears, cleaned, ok.
    Found piece of cut master inside transport unit eventually.
    Made sure clamp cam and clamp transport cam were back in correct position as per manual and all gears replaced correctly.
    Replaced unit.
    Didn't realise the metal bar out back of unit went between two senors and that had been bent during work. Straightened metal strip and replaced sensors which had been knocked loose. As sure as I can be that strip of metal is now correctly in centre between two sensors when unit is rolled back in.
    When replacing unit as I found it, realised that it had actually been put in originally off centre (front tooth back one from back tooth). I'm certain that is how it has always been since new. I replaced it straight with teeth parallel. [wondering whether to put back in crooked? Could it have gotten used to being like that and worn so it can only work crooked?]

    Since then I have to manually remove each master before making a new one as it will not remove at all. By removing manually I get this series:

    Turn machine on
    Make sure no master on drum 1
    Job through
    A05-304 Master jammed in disposal unit 1
    Nothing there but remove and replace unit
    A04-303 Master disposal error
    Pull out drum 1 and there is a completely black master on it.
    Remove
    Resume
    Master made.
    Once machine has done this for the first master, all subsequent masters are made with no errors as long as I manually remove master before sending job through.

    Any thoughts greatly appreciated please.
    Riso tells me to buy a new master making unit but I don't see why that would be the case when it was working before this and I can't afford one anyway.
  • jermyth
    Riso dude

    250+ Posts
    • Mar 2011
    • 439

    #2
    Re: MZ770 Riso master making error

    Cheat door switch, use flashlight and watch drum & clamp run through making and disposal, I'm thinking the the clamp is not opening enough to eject the master. If this is the case, you need to reform the pins that the cam hits to open the clamp and ejection plate.
    Good luck.

    Comment

    • LizW

      #3
      Re: MZ770 Riso master making error

      Thank you very much. Will do on weekend as soon as this week's run is finished. Will let you know how it goes.
      When you say reform I hope you don't mean rebuild; just readjust.
      As an addendum to the previous post:
      This week I started the riso up then checked before sending job through... the all black master had been put on drum 1 before job sent through (?)
      Don't know if this helps or hinders the investigation.

      Comment

      • LizW

        #4
        Re: MZ770 Riso master making error

        Just to let you know I haven't ignored the follow up: I've managed to tear two ligaments in my knee (I went one way, armful of paper went the other and knee managed to find a third direction!) and have discovered that even sitting in a chair trying to work on the riso isn't much fun. Being good and doing all the physio's exercises, much better this week. Hope to have further news on riso problem next weekend. Regards, Liz

        Comment

        • jermyth
          Riso dude

          250+ Posts
          • Mar 2011
          • 439

          #5
          Re: MZ770 Riso master making error

          Ouch! I hope you heal soon, but take time to heal well. Good luck.

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