Grounding issue with rim

#1

Not strictly Simucube related but was hoping the knowledge here could help clarify and narrow down the issue.

I have a Simucube 1 with Small Mige (BISS C encoder) and a Q1R quick release. The last week or so the button box on my rim has been temporarily disconnecting if the wheel is turned very quickly left or right. While investigating I noticed that the button box disconnects completely when I remove the wheel by separating the quick release. I assume therefore that the ground connection in the usb cable to the box has become damaged somewhere, so it is now grounding via the motor.

I assumed the disconnecting when turning quickly was due to some minor play in the qr so I ran a grounding wire directly from the button box to the base side of the qr. However it still disconnects when turning quickly.
Is there a something with how the Mige or encoder works that would explain why the ground signal would momentarily cut out when the shaft is rotated quickly?

I just want to ensure that it is a grounding issue with the cable and not something else at play etc.

#2

You probably also have a data wire damaged in the USB… The Grounding wire would turn off the device (causing a disconnect) but a data wire break will cause a disconnect but without losing power or ground.

#3

Thanks Brian…The part that is confusing me is why the connection would disconnect when the wheel is turned quickly but not under normal driving conditions.
I have played with the cable and where it connects to the box and no amount of movement with those will make it disconnect, so it seems to be something about it grounding through the Mige that is causing it. I was really just interested in understanding if there was something about how the motor or encoder works that would explain that behaviour, just so I can be positive a new cable will fix it etc.

I know you and some of the other OG OSW guys probably know these motors pretty well by now!

I might try running a longer grounding wire to somewhere else to see if it still happens, or maybe try and put together a new cable myself, as the official one is pretty expensive once postage is added.

#4

Intermittent connection is a common issue with a broken cable. What happens is that the wires are broken inside the casing so when the wire is at rest it connects as if nothing happens then when you turn the wheel the wire twists or rotates causing a disconnect… BTW Manual manipulation won’t always allow you to find the issue especially if it happened somewhere middle of the cable and not actually at a plug. Sometimes you can get an idea of where it might be if you have a kink in the wire.

We had this issue with some of our early wheelbases that we produced as we were using an off the shelf USB cable, everything looked fine on the outside but internally wires were being broken. So we redesigned a custom cable with MUCH thicker internals (out of USB Recommended Spec but WAY more durable and it works properly).

You should be able to test this out by not turning on the wheel base (or tripping the e-Stop) and seeing if the wheel disconnects without the wheelbase running. I suspect it will.

Grounding issues usually result in odd input behavior (double button presses, presses without actually pressing anything, input fluttering) not really complete disconnection.

#5

Just a quick update… Turns out it was a ground issue. Took the connector apart and the ground wire had broken away from it’s pin. Soldered it back in place and everything seems to be working perfectly again. Turning the wheel quickly no longer causes any disconnects etc.

Thankfully a nice easy fix!

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