[Lc1975]

Hi..

Have a issue regarding the eletric part with my cnc..

Every time that i turn on the machine and my desktop i note that the motors of the axis starts to move alone a few tenths of milimeter very little but moves... X, Y or Z

I can hear the motors moving like as interference on the same...

But only when the desktop starts with the bob connected..

Then if i start the program and i note a very little difference in the cutting of the material...

The desktop is new..
I have a fx990R2 with a paralell board.. The cable is practically new too....

When i bought the kit from ebay e made a wrong connection instead of 5v i put 12v, the bob burn a smd, but it was changed and then tested and that person say that the bob was ok..

But every time that i have the bob turned on and then turn the pc it make interference with the axis motors....

Is there any way to test the DB25-1205 or maybe a new board??

The steppers motors is DM542A and in the diagram and for what i see the neutral of the power is not to be used.. Only has the 5v connected..

Regards.

[James Newton]

Why don't you home the axis on power up?

[Lc1975]

I try to home the avoid but they are dislocated tenths of millimeter...
And I'm still learning to work with this... I read a lot but I have a little difficulty to translate or understand in my language.. Here I have 0 help...

[James Newton]

I don't understand. Are you saying that the unit is still off after homing? Or it's off after you home and then power down / back up?

If it's off after homing, your home switches aren't good, maybe.

If it's off after homing and then power cycle... don't do that! Home everytime you power up.

[Lc1975]

It´s like this..
I have the machine stoped..
But after a while i hear a something like a bump and i go to see the position of the machine and the machine moves a little maybe a tenths of mm..

Ex:
I have X on position:
+100mm

and Y on position:
+50mm

Z on
+25mm

After a while when i hear that "bump" a few times between a period of maybe 10 to 20 minutes the axis moves...

Ex:
X: +100.2mm
Y: +50.3mm
Z: +25.1mm

Without doing nothing on mach3 or on the motors

Only when the bob is connected to the pc...

If i remove the pararell cable the axis don't move...

Thats what happen..

[James Newton]

That sounds like EMF... electrical noise. Are there motor cables or power wires near the parallel cable? Is the parallel cable a nice big fat quality strong cable? Oh, and is the parallel cable more than just a few feet long?

[Lc1975]

The only cables that I have near the parallel cable is from the bob (5v), no motors in the electric of my house, the vfd is connected to a ups...
I used the cable that came with the kit it's a very weak cable...
I get a new cable and this is more fat and robust... on this moment I changed all cables and I will try again and say if the problem persist...
Thanks for the time and tip.

[Lc1975]

Hello.
Maybe i solved the problem...
Bought a new bob.. when see wiring the connections of the steppers to the board is by the DIR- and PUL- and i never used like that always used with PUL+ and DIR+
Used like the wiring and until now no more interference with the axis motors...

Solved...

[ely862me]

Hi guys,

I have a similar problem: when I power on the drivers then the PC, the steppers get locked. At loading Windows they unlock and lock immediately. Only when I start Mach3 they get unlocked again.

The BOB is db25 1205 and the manual says its normal output state is high, so until Mach3 starts to control the lpt port they behave like that.

The drivers are DM860 and they are supposed to have a soft start to prevent jump on power up, but when pc starts up they jump about 3 times (3 on-off cycles)

Without the db25 cable connected to the PC the output is hi, and the motors are still locked. I want them unlocked until I start Mach3.

I connected the spindle on one of the outputs, and the spindle starts on power up, then it stops when I start Mach3.

Hope you understand all of this.