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Readout flickers with motor running (glass scales)
Ok... Here's a link to a quick video, demonstrating the issue. The TouchDRO adapter is plugged into an outlet that turns on with the main power switch. I have also tried plugging it into a different outlet, with a different USB power supply, as far away as the scale cables would allow, with the same result.

I didn't notice before, how both readouts drift down and settle like they do in the video, when the tablet first connects. Not sure if it's always done that.

The flicker is the same before, and after the solder bridge issue mentioned in my previous post.

Also, you can see the Z-axis readout flicker getting worse as the motor comes up to speed, but as soon as I press the button to turn the motor off, the readout is rock solid. Looks like the Y readout flickers once or twice right after I hit the button to start the motor, but otherwise stays solid.

The motor itself is a Kingston Conley, 3/4hp, 3450RPM, 220V 60Hz 3-phase unit from sometime in the 1930's to mid-1940's. I brought it to a local electric motor shop when I first bought the surface grinder, and they gave it a clean bill of health.

The VFD is a Lapond SVD-ES 1ph input, 3ph output unit. Cheap import.

The scales themselves are the usual generic glass scales sold by any number of resellers on eBay.

That's all the info I can think to provide. Let me know if you need more.

And here's pictures:

These 2 show how close the scale is to the motor.

[Image: obE3P8U.jpeg]
[Image: C11pZIg.jpeg]

Next, this is the current setup. I know it's a mess... I'll eventually put the adapter in an enclosure, and make everything nice and tidy. This is just for the testing phase. Separating all the cables and such had no effect.
[Image: j8h28OE.jpeg]

Next is the connector. The scale pinout is 1=+5v, 2=0V, 3=A, 4=B. They're each connected to the appropriate pin on the adapter connector.
[Image: cFIqtEi.jpeg]

Finally, the adapter itself. The ring terminal wire is connected to the chassis of the machine.
[Image: 9GtsyVM.jpeg]
YouTube: FnA-Wright Engineering

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RE: Readout flickers with motor running (glass scales) - by MidniteMachinist - 07-27-2021, 12:52 PM

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