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banging machine

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  • banging machine

    I have a bunch of shopmaster 250 and when they under a low load -under 90 amps- they will make load banging noises. I have opened the case and looked to see if something is loose, but all seems to be fine. I have talked with my sales rep and all he tells me that the shopmaster is old and he can't think of why it would do that. Has anyone else had this happen to them? Any help would be greatly appreciated.

  • #2
    The noise your hearing is comming from the side covers. When you weld the coils magnitize the iron core shunts. This in turn causes the outer covers to pull in and shake. Under a heavy load, the covers probably don't shake as much since the covers are pulled tight.

    If you remove the outer covers, the noise vanishes. All you have to do is put some foam rubber against the outer shunt coils, and reinstall your side covers. Presto no more noise.