Acorn DMM Servo, wrong axis moves, and other issues.

[farrcustomfab]

Just remember that when you drop the resistor you need both the 24VDC and 5VDC sources off the Meanwell PS (depicted in the drawing ShawnM attached). I ended up pulling the circuit board entirely from the DMM cables -- would've been easier to just start with fresh DB25s. Further DMM offered to refund if the cables were returned undamaged; a chance to get $135 back (for 3 axes).

[ShawnM]

Yes, as farrcustomfab pointed out, you need both 24v and 5v. Please study the diagram and understand what is happening BEFORE you just jump in and start changing things.

Starting with fresh DB25 cables and cutting them in half makes sense for sure. You end up with a lot of extra wires but you can just cut them off as you only need 8 wires. Or if you have the solder skills and equipment just get some DB25 connectors and hoods and solder up your own cables using some shielded CAT5 cable.

[the_Swede]

Hi Shawn.
Once again, thanks for your reply.
I´ll do some rewiring this weekend and see if it makes the issues go away, and hopefully be able to close this thread as solved.

Best regards:
P-J

[ShawnM]

Great and please update us as to what happens. Hopefully together we can get your issues resolved and get you making some chips.

[the_Swede]

Just remember that when you drop the resistor you need both the 24VDC and 5VDC sources off the Meanwell PS (depicted in the drawing ShawnM attached). I ended up pulling the circuit board entirely from the DMM cables -- would've been easier to just start with fresh DB25s. Further DMM offered to refund if the cables were returned undamaged; a chance to get $135 back (for 3 axes).

Yeah, and me being all happy about being able to remove it from the cabinette and just running everything from the larger 24VDC converter that I have installed... guess I´m putting it back in to get that 5V...

Further more, the cicuitboard in the DB25 said 2k resistor whilst there was an 1k installed. Some revision that DMM made along the way?
(Never been a fan of dropping resistors... )

[ShawnM]

You should be using the Centroid supplied dual voltage power supply for the Acorn anyway. It's best practice to use that power supply for the Acorn only and run all your other ancillary devices and sensors from another power supply.

[the_Swede]

Hi.

First of all, I would like to thank you all for the support and time you have given me.
I can gladly report that all axis are moving and behaving as they should.

Just as you pointed out, the DMM servos should be run via the DB25 connection, and I can not for any reason understand why the heck DMM gave me the diagram with the screw terminals.... and why they sell that fly out lead with the dropping resistor. (Which I´ll get back to in a minute.....)

Never mind the cable management, just wanted to confirm functionality first.

As you might remember, the Z axis had its own agenda and was working when it felt like it. Well, I found the reason....

The enable pin was not soldered to the f(#&ing circuitboard, and there´s an exceptionally vivid email on its way to DMM in a couple of minutes.
Considering they had the audacity to charge me 45$US per cable, it is not acceptable at all.

I know its not much to see, considering the crowd circulating on forum a like this, but here´s a short clip of the machine moving and really boosting my mood this weekend.
(Never mind the sound of the busted end bearing on the Y axis, it´s on back order )
https://youtu.be/99R-cb0cL4U


So once again, thank you all.

[ShawnM]

This is great P-J, so glad you have everything working as it should. No matter how many machines I retrofit or work on it's always satisfying to see it move for the first time. Move correctly I mean.

It appears that the consensus for the DYN4 drives is the DB25 without question and no real need for the DMM cables. Best to make your own if you have the skills.

Thanks so much for the update and I'm glad you got it working.

[slodat]

Swede- I feel your frustration. For whatever their reasons are, DMM continue to sell the cable and send the schematic that many have found to be problematic. Once I switched to the DB25 step/direction signals, my DMM DYN4 machines have worked flawlessly. I use a 10' Amphenol CS-DSPMDB25MM-010 cable. Cut in half and there's plenty of cable to work with, and it makes two flying lead cables. Amphenol makes high quality cables. Online electronics supply houses show it for about $35usd.

I did a lot of testing on this a few years ago. The threads and results are on here.