VFD interference problem

[Clive S]

I am not surprised that you have emf problems I think I would remove the vfd from the control box plus sort out the rats nest of wires try to keep or the signal wires away from the power wires and avoid running them side by side.

If you have to cross power wires do so at 90' if possible. Have you connected all the screens to one star point? I don't think it helps having the PP ribbon cable I would try and replace that by connecting the PP cable from the PC direct to the BOB without the ribbon cable.

You have the basis of a good control box but you have not made the best use of the cable management in there.

edit: Is that a plastic control box? have you mounted everything on to a backplane (ie metal plate) I think one of your main problems will incorrect grounding