Quote Originally Posted by Kitwn View Post
What gobsmacked me the most was the amount of noise before I ever put mains on to the VFD. It's enabling the motors that introduces all the trouble. And the fact that the same noise is on the ground of the BOB. I thought the screening and earthing was quite reasonable but noooooo!
That doesn't really suprise me - I remember when I powered up my first PWM audio amplifier - which was switching roughly the same voltage and frequency as a decent microstepping drive - and the radio in the workshop promptly went off. Holding a 'scope probe 6" above the speaker leads gave a few volts of noise in thin air, I ended up using screened speaker cable :. Are the cables to your motors screened I wonder? As with the sensors when I extended my cables I cut them very short then extended with screened (2 pair) which might explain why I've not had any problems in a setup which seems somewhat similar to yours - I'm using basically the same type of sensor albeit in the M8 size. The motor cable screens I returned to the HT- pins on the drivers (always return your shit to where it's generated!) which then has a VERY SHORT ground lead down to the aluminium back plate of the enclosure which acts as a ground plane - being an RF man you'll appreciate the benefits of those.