VFD interference problem

[eurikain]

Well, guys, problem solved ! Guess who was right ??????????
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JAZZZZZZZZZZ !!!!!

The 5V signal to the BOB had two routes to 0V... getting the 5V from the PC solves the problem :) This is why disconnecting the PP cable was causing the noise to go away, since it would suppress one of the two 0V possible routes.

Thanks for your help !

I do have one more tiny issue:
Mach3 controls the RUN/STOP signal and spindle speed fine, but the BOB seems to output an unstable signal for the spindle speed control. When running, the frequency can't stay still and keeps going up and down by 1-2 Hz, causing the spindle to run faster/slower (you can hear a slight increase/decrease in speed).

I can bypass this issue by disabling Mach3 speed control and only do the RUN/STOP, but while I'm at it, let's fix this issue if possible :)

[JAZZCNC]

Well, guys, problem solved ! Guess who was right ??????????

Always helps with solving problems if you give us all the facts.!!. . . . . It's was a rather important bit of info you didn't make available, esp considering the BOB and been accused prevously.!

I do have one more tiny issue:
Mach3 controls the RUN/STOP signal and spindle speed fine, but the BOB seems to output an unstable signal for the spindle speed control. When running, the frequency can't stay still and keeps going up and down by 1-2 Hz, causing the spindle to run faster/slower (you can hear a slight increase/decrease in speed)

It's called Crap Bob Syndrome and I doubt there's much you can do for it.!!

[Clive S]

It's called Crap Bob Syndrome and I doubt there's much you can do for it.!!

You could try giving it an Asprin

[JAZZCNC]

You could try giving it an Asprin

Nah Bullet straight between the eyes works every time.

[eurikain]

You dorks :D

Well, a clue could have been that when the 5V PSU was off, its power LED was slightly on (not fully, but you could see some light), indicating that power was flowing from THE PC through to BOB to the 5V PSU (receiving -5V I guess).

Anyways, problem fixed, let's now move on to cutting !!!!

[cropwell]

You dorks :D

Well, a clue could have been that when the 5V PSU was off, its power LED was slightly on (not fully, but you could see some light), indicating that power was flowing from THE PC through to BOB to the 5V PSU (receiving -5V I guess).

Anyways, problem fixed, let's now move on to cutting !!!!

Had you originally connected V- on your 5v PSU to GND ?

On your BoB the terminal marked PC GND is actually the current return path and should not be connected to GND but only to V- on the power supply. The BoB itself has a GND plane connection next to the 12-24v terminal, which is the current return path AND GND for the BoB electronics.

[eurikain]

Yes that's what I had done. PC GND to 0V of the 5V PSU, and PC +5V to +5V of the 5VPSU.

Can you provide a quick diagram on how to do what you're explaining ?