Analog spindle signal

[tfhess]

I just received an Acorn swap out board. Ran a bench test along with the analog spindle signal test routine per Marty's video. Everything checked out fine (see first report, 1:36 pm). Then I set up the board per my machine (see 2nd report, 1:52pm) and reran the analog signal out again and this time it was outputting improper voltages. I cannot figure out what is going on here. Any help would be appreciated.

report_30E283D7915E-1116215368_2022-06-10_13-52-21.zip

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report_30E283D7915E-1116215368_2022-06-10_13-36-27.zip

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[ShawnM]

When you ran the first test was it a true "bench test" with the Acorn laying on the bench with nothing else hooked to it? On your second attempt was the Acorn installed in the enclosure or on the bench?

[tfhess]

Yes, first was a bench test, second was in my enclosure

[ShawnM]

Well there ya go, you have a noise issue. Are you using shielded cable from the Acorn to the VFD? Are you grounding the shield only at one end, closest to the Acorn? Do you have a .1 mfd cap across the output?

[tfhess]

Yes, no and no. Sounds like I need to ground and add a cap. Thanks.

[suntravel]

I use two caps parallel, one with an 10 Ohm resistor in series and shielded twisted pair, shield to ground in the cabinet only

Uwe

[rk9268vc]

Just to fill you in on the "why?"
The capacitor across the + and - command wires acts as a low pass filter, where the lines themselves are the impedance.
This acts to filter out high frequency noise.

Also if you are running stepper drivers, those are extremely eclectically loud and should be property shielded from your controller.

If your voltages are not fixed by this, make sure you have proper grounding. In my experience, the drive or VFD ground needs to be tied to the command common, which goes into the acorn. Consult your driver's manual to make sure you are wiring it correctly.

there are more possible causes, these are in my opinion the most likely without more info. maybe send a picture of your enclosure and more details?
good luck

[suntravel]

On my builds even with good shielding the 10V signal starts to swing when the servodriver is connected, but with the filter it is very stable.

Uwe

[tfhess]

Not being an electronics whiz by any means, I am not sure where and how you connected your filter. Could you share a circuit diagram? Thanks again.

[Nigelo]

I had a similar issue with my router a while back. Take a look at my short thread through to full resolution.

https://centroidcncforum.com/viewtopic.php?t=5561

Hope this helps