Disc sander switch

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robgul

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I have a Ferrex Disc/Belt sander (rebadge Sheppach) that appears to have a faulty on/off switch - pressing the ON button and it starts and runs as normal - but taking your finger off the switch and it stops - i.e. it doesn't "lock" on.

The machine is under warranty and I'm waiting on a response on the fault ticket - but to satisfy my curiosity I've been doing some research .... a YouTube film shows how to to replace the switch - that's simple BUT there is a unit with a copper coil in the plastic box that houses the switch with some connections See pic (the back of the switch is at the bottom of the picture

Does anyone know what the coil unit does please? [I'm NOT going to attempt a repair as it's under warranty]

sander-switch.JPG
 

Solverson

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It looks like a transformer - maybe its a contactor? I've never seen one that size but they are common in large machines. They create an electro-magnet when you first press the on switch. This holds the switch closed until you hit the off button. If that is what it is, a fualty one would cause the switch not to "lock" on.
 

robgul

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Just heard from them - replacement unit is being sent - from Germany .... hopefully not delayed by the current shipping issues - to paraphrase a classic headline (which was about fog) "BREXIT - Europe cut off from England"
 

HamsterJam

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Does anyone know what the coil unit does please?

Is it an NVR switch?
If it is, I think Solverson was on the right track and it will be the solenoid coil that keeps the power on after you release the start button and until either the power fails or you press stop button.
 

robgul

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The spec for the specific machine is a bit vague about whether it's an NVR but the identical machines from other brands (badge engineered) do say they have an NVR - so that's probable. As my post above a "new switch" is on the way to me under warranty - whether that's just the on/off part or all of I don't know . . asked, but no answer.

Slightly surprised that they're sending an electrical part rather than calling the machine back to fix - not a problem as I'm pretty handy . . . or I probably wouldn't be on this forum ;)
 
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