Quote Originally Posted by JAZZCNC View Post
That would be my first move. It's a much debated thing but I never ground both ends and I never have issues with these cheap sensors. Thou like voice coil mentions I cut the shitty cable off close to the sensor and use screened back to the board and ground it.
That will be test one. How many layers of cling-wrap do you think I'd need round the spindle to insulate it from it's bracket if that works?

Interestingly I get the same amount of glow from two sensors. The Y one which goes to a junction box and onto screened cable before joining the VFD cable in the drag chain, and the Z which has the original cable running in a common length of drag chain before being connected into the same (8way) screened cable as the Y.

Voicecoil,
I do take the point about cutting off the original cable short and going screened, I shall probably do that anyway. Possibly with some balanced audio cable if I have enough, it's thinner than the other stuff I have in stock and Auntie would surely approve.

Simon,
I'll have a look at the full video tomorrow, but I've tried winding a few tuns of the cable onto a ferrite ring at the sensor end and adding capacitors as described earlier at the joint into the multicore. Much to my disappointment it made no difference. Next will be to hook up my oscilloscope and look at the noise level with different solutions.

I'm between 12 hour shifts tonight (and very glad to be still working) so it will be Wednesday before much more gets done on this. Thanks for all the input everyone.

PS I have this cunning design for a low cost DIY optical fibre interface that would solve all these problems but I really would like to get the machine upgrades finished right now and actually make something with it!!!