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Speed pots on a ST1200HD

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  • Speed pots on a ST1200HD

    Can the speed be changed on these units I could tell the cartoon I ran was running way faster than normal it did have new belts installed could that be a problem?

  • #2
    Hi Jim,

    The ST1200HD has an AC motor, which pretty much means your frame rate is determined by how fast they turn the generators at the power station. The pots are for a DC motored machine with an electronic speed regulator.


    The pulley for the motor belt has two sheaves: a smaller one for 60Hz. counties and a bigger one for 50Hz. ones. If your new motor belt was installed on the 50 Hz. sheave and you plugged into 60 Hz. power your frame rate would be 60/50*24FPS=28.8FPS.

    Fast frame rates (rather than slow) are the exception for these machines, so this is a good bet to fix this.
    Last edited by Steve Klare; March 25, 2022, 06:56 PM.


    • #3
      Hi Jim in the UK Machines, you can move the Main Motor belt over to the left pulley on the motor and the ones above it looking in from the back.

      That will slow it down.

      I`m not sure if its the same in the USA machines and its handy if you have taken the rubber off the shutter ( ones that have it ) as it takes the machine speed back down a little as the rubber coming off speeds it up.

      I tend to run mine on that anyway as much quiter, and little difference in the sound etc.

      Best Mark.

      PS here a video of an australian machine.

      The main belt is in the right looking in from the back.

      Shift that over to the left and don`t worry about the small belt if you have the two options.

      If you do, hope it works.


      • #4
        Thanks mark and Steve I’ll look to see where the belt is located


        • #5
          It turns out that the 2 belts were installed on the wrong pulleys by switching them around the speed issue has been corrected thanks for your input.