Need Help: Acorn, DMM DYN4 New Build

[farrcustomfab]

Tried swapping in the 240VAC lines; no change, symptoms persist. Swapped back to 120VAC (but using the ground from the 240VAC feed...to see if I had a ground issue) and monitored the scope in DMM DRV, back to being perfect (data reading in scope position mode shows variance of +/- 1 on all drives). Ran it through a gcode program: flawless. So there's something with the 240VAC supply.

Note: my EMI filter is downstream of my 24VDC power supply. I'll try placing the main EMI filter upstream from the 24VDC supply, and then I'm out of ideas.

The 24VDC supply is a Meanwell NDR-120-24 and is rated for 240VAC input (and outputs 24.2VDC whether it's receiving 120VAC or 240VAC). I spoke with a rep from DMM -- he said the 245VAC actually received at the drives isn't an issue (despite the stickers that came on the drives saying "do not exceed 240V").

[farrcustomfab]

No change with moving the main supply EMI filter upstream. I'm considering buying a 240V to 208V transformer which should put me at 212VAC (cheaper in time and materials than running a new 120V circuit). Has anyone in here used a buck boost step-down transformer for a home CNC? Anyone had a similar problem with 120V vs 240V main supplies with Acorn and DMM DYN4s?

[tblough]

You might run a search - I seem to recall another thread sbout DMM problems with 240V and not with 120V.

EDIT: Got it down to just a couple of pages to check - https://centroidcncforum.com/search.php ... mit=Search

[farrcustomfab]

That's really helpful (seriously). Working up from ferrite chokes, to shifting over to the Acorn DB25 (using the new Rev7 wiring diagram) vs the header connectors and ultimately going with 120VAC main power if all else fails. Will report back when resolved or if none of those work. If nothing else, may someone else can learn from this.

[wadyciprian]

I have this same problem and I still have not found a solution to calibrate the axes but apparently steps are lost, I need help I have a dmm 1kw servomotor

[lavrgs]

I have this same problem and I still have not found a solution to calibrate the axes but apparently steps are lost, I need help I have a dmm 1kw servomotor

If you have DMM servos/motors it is pretty easy to check if you are losing steps. You need their tuning cable and use their DMMDRV app to monitor the motors. Run a cycling program (25-50 cycles)on each axis ex. 0 to -1 to 1 to zero and monitor the final position.
There is detailed info in this threadhttps://centroidcncforum.com/viewtopic.php?f=60&t=6472
I ended up buying a differential board from KENTONSJ that solved all my accuracy problems caused by noise

HTH

[wadyciprian]

Where can I buy this differential board, do you have any link?

[lavrgs]

Where can I buy this differential board, do you have any link?

Find KENTONSJ on this forum and contact him

[farrcustomfab]

Took a little while to come back around to this, but I wired it IAW S14969.r7: DB25 for Step and Direction, but header for Enable. Took apart the DMM flying leads, removed the 1.2K resistor and wired those two terminals to 5VDC directly. It works perfectly in bench test mode on all three axes. No more drift/jitter. Doesn't mean I won't lose steps once the machine is fully assembled, but with no load it works flawlessly now.

[ShawnM]

Glad to hear you are making progress, please keep us posted. The DB25 seems to be the answer for many with the DYN4 and considering it's a 5v drive it just makes sense.