VFD interference problem

[eurikain]

Alright, so after spending the day trying to fix this with Graeme on Skype, we seem to have found the source of the problem.


I have connected all screens to the star point. I've taken the VFD out of the box, power is separate, it's completely diconnected from the control box, and still, no improvements.


Turns out disconnecting the PC solves the issue. So it seems like there is a grounding problem with the BOB. As JAZZ said, it's a cheap chinese BOB, so I might have to change it.

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

Fiber glass cabinet. Fireproof plate in the back. No metal.

Like Cheap nasty BOB.!!!!!

Jee JAZZ, you don't like them.. :D !

One last thing you haven't earthed the PC case to control box have you.? If so remove.

Nope, not intentionally, but apparently it is through the BOB.


One thing to note. When there is no power to the control cabinet, but the PC is plugged and turned on, the BOB receives 5V, but the 5VDC PSU led turns on, apparently because it receives power through the BOB ! Weird...

[JAZZCNC]

Jee JAZZ, you don't like them.. :D !

Nope and now you know why. You have been lucky to find it quickly this isn't always the case, in fact often not the case. Which is exactly why when these troubles come my way first thing I do is rip out the BOB.

[m_c]

You're most likely getting a ground loop through the parallel cable shield. As you're using a ribbon cable internally, try unscrewing the parallel connector from the cabinet and see what happens. If it cures the problem, you can either come up with some way of insulating the connector, or just cut the cable shield near the connector.

[JAZZCNC]

If it cures the problem, you can either come up with some way of insulating the connector, or just cut the cable shield near the connector.

It's Fibre Glass cabinet so won't be that.!!

Okay but now, where do I go ?

The good old US of A. . . . . PMDX126.

[eurikain]

The good old US of A. . . . . PMDX126.

How about NOT USA ? CSLab ? And while I'm at it, why not go with ethernet motion controller instead of a BOB ?

[m_c]

It's Fibre Glass cabinet so won't be that.!!

Good point. I'll just go back to sitting in the corner and keeping quiet!

[JAZZCNC]

Good point. I'll just go back to sitting in the corner and keeping quiet!

Nobody puts Baby in the Corner.!! . . . . You keep on Dancing Mc

How about NOT USA ? CSLab ? And while I'm at it, why not go with ethernet motion controller instead of a BOB ?

Well yes that would be my first choice but your talking different animal and cost depending on model.

[eurikain]

Yes but if I order the PMDX 126, 160 Euros + tax when it gets here, you're looking at the same price than the 230 Euro 4 axis motion controller they've got at CSLabs. Plus, really, I think I can re-use it in the future for another build.

Are there any choices other than CSLab, for a decent controller ?

[eurikain]

Nope and now you know why. You have been lucky to find it quickly this isn't always the case, in fact often not the case. Which is exactly why when these troubles come my way first thing I do is rip out the BOB.

Okay but now, where do I go ?