Centroid Community CNC Support Forum

Hi again
So after yesterday fireworks I managed to connect the Lenze drive back to Acorn and it works without any fireworks this time. Problem is that the spindle rpm are unstable. As from yesterday the acorn pass spindle bench run so I’m sure I get right voltage out of acorn spindle control pins and it should be connected properly to acorn. Pin7 to com on acorn and pin8 to vout on acorn. By checking voltage what comes out of acorn with lenze connected I get unstable reading as well (for example 3.6-4v) Lenze was tested with battery and potentiometer without any problem. Any idea why is that

Here is video
https://www.dropbox.com/s/jqjph02q4p82o ... 7.mov?dl=0

Do you have the VFD spindle cable shield grounded at both ends or just one end? I’ve seen this cause unstable rpms on some VFD’s. Also, you may want to add a .1 uF ceramic capacitor across the analog outputs on the Acorn board. Could it be possible your fireworks display damaged something?

ShawnM wrote: ↑Sun May 02, 2021 7:49 am Do you have the VFD spindle cable shield grounded at both ends or just one end? I’ve seen this cause unstable rpms on some VFD’s. Also, you may want to add a .1 uF ceramic capacitor across the analog outputs on the Acorn board.

Only one end is connected to ground. Should I connect both ends to the ground? Did u mean to add 0.1uF capacitor on spindle control outputs?

You can try grounding both ends, sometimes it makes a difference. As for the cap, yes, add it across the analog output wires on Acorn. Simply insert one leg into each side of the H8 connector on the Acorn.

ShawnM wrote: ↑Sun May 02, 2021 8:00 am You can try grounding both ends, sometimes it makes a difference. As for the cap, yes, add it across the analog output wires on Acorn. Simply insert one leg into each side of the H8 connector on the Acorn.

Ok thanks... I have to order that capacitor so when I get it I will come back here with the result

Shawn,
FYI, he started a new thread. His drive is not a VFD its a DC Controller....
What kind of wire are you using?
Define "unstable" in terms of RPM

Marty

martyscncgarage wrote: ↑Sun May 02, 2021 9:05 am Shawn,
FYI, he started a new thread. His drive is not a VFD its a DC Controller....
What kind of wire are you using?
Define "unstable" in terms of RPM

Marty

Hi... that is right it is dc drive... I thought it will be easier to start a new thread for new issue.
I use 2x 0.5mm2 shielded CY cable from acorn analog output to the drive
I can’t tell exactly how how much it is unstable in RPM because I haven’t connected my encoder just yet but it is roughly 0.4V difference in one speed. You can even clearly hear that changing rpm from the video I have shared here When I checked the output voltage with lenze drive connected at one speed it gave me reading between 3.6V to 4V. Without the lenze drive the output voltage is stable

Forget everything I said then, I assumed a VFD as I've used Lenze (AC Tech) SCF series VFD's in the past. Maybe he should have kept this in the same (old) topic.

ShawnM wrote: ↑Sun May 02, 2021 1:38 pm Forget everything I said then, I assumed a VFD as I've used Lenze (AC Tech) SCF series VFD's in the past. Maybe he should have kept this in the same (old) topic.

It is lenze 534. Here is link to manual.

http://www.lenze.org.ua/pdf/530_Speed_c ... 202_EN.pdf

Sorry for creating new thread for this. It is a new issue so it seems ok to me to create new question

The capacitor may help