Replacing Advanced Motion Controls "brush type 12A8 with "Axcent" amplifier

You shouldn't need another encoder. Why, do you think there is something wrong with your encoder you have?

Did you try connecting the A,B and ground from the encoder to the servo drive? Simply run a few wires from the terminals those wires connect to on the 7i77 over to the drive. I didn't suggest it before because I wasn't sure if it was a good or bad idea, but I have heard of others doing it. I had hoped someone like Peter would chime in and say yes that is ok or no this is how you should connect it. (but the geniuses have been conspicuously silent on the subject.)

Todd, Many thanks!! This is from earlier post: When I tested by swapping (x axis encoder and power cable at the back of cabinet) with (y axis encoder and power cable at the back of cabinet) in addition to trying to tune this (use "test" & "cancel" after each change) axis as well. I have saved a file for setup axis x and a 2nd file for y axis. Todd, I just read your post.

I am tiring to tease out the issue, this is what I have tried. I had spent a lot of time over the weekend tiring to duplicate a screen shot from earlier tuning. The only way close is the swap. I am not completely shore.

OT-CNC, Many thanks! I have not tried your "look for a clean square wave coming from the encoder." post yet! OT-CNC, The attached pics are what axis x & axis y look like when the power supply is on, the drives are not engaged, the corresponding, x axis or y axis hal scope is used as to set for pic. Some of the gains were up to show detail. I did not see square wave, but not shore of set up.

many thanks

Todd Zuercher wrote: Did you try connecting the A,B and ground from the encoder to the servo drive? Simply run a few wires from the terminals those wires connect to on the 7i77 over to the drive. I didn't suggest it before because I wasn't sure if it was a good or bad idea, but I have heard of others doing it. I had hoped someone like Peter would chime in and say yes that is ok or no this is how you should connect it. (but the geniuses have been conspicuously silent on the subject.)

This is to test out the 7i77 circuity? If I understand attach jumpers from where the x axis encoder attaches to 7i77 (these are the very same seen in the pic coming from the encoder, except the attachment point is the 7i77 PCB). Attach other end of jumper to the AMC drive at P1 (Pins 4 & 5)? See P1 connector attachment (page 4 of 9).

Many thanks!

Just to be clear, the "jumpers" that I was referring to are the small black plastic bridges on the 7i77 that can be moved to configure different settings. Such as the power options. Set those based on the manual.
I think you are referring to the wires going to the terminal blocks as jumpers correct? We are suggesting to connecting an additional set of wires from 7i77 A and B to A (pin7) and B (pin 6) on the AMC. You may need to share ground for it to work? PCW would know.

I don't know why you would connect the encoder to pin 4 and 5? Those are your analog inputs. GND and Aout from the tb5 connector go to there.

Last, if you make up a wiring harness use shielded and twisted pair wiring if you can. Connect the shield drain on one end only, the control cabinet star ground location.

This is to add encoder feedback to the drive so it can operate in velocity mode. The encoder can be used for both the position feedback to Linuxcnc and the velocity feedback to the drive (if you connect it to both).

OT-CNC, Thanks! My poor pick of words, ok jumper are very specific term, I will be careful in the future. I am thinking temporary, just to evaluate a test. I want to get it correct, just need some time to ponder, maybe.I can see in the last "look for a clean square wave coming from the encoder" in recent post that the "HandWheelY.png" is closer than the handwheelxpng pic to being a square shape. Is this a good test for the encoder? Am I looking / tracing the correct pins, as to get usable knowledge? If there is specific question about setup that only the A-M-C may know, and if I can understand the question well enough to describe to the tech, I may get an answer.Many thanks

Edit1: Todd Many Thanks!!! Just read your post, I understand why now, I will reread and try to run temp wires, to see if an additional encoder feedback can be arranged. It seems to me the plug has wires that were never used or went nowhere. I need to get fresh look at the set of wires coming back to electrical cabinet as to where they go. Many, many thanks!!

Edit2: The pic (this pic too large to load) of the back of the pass through, there are several wires going all to the same lead, this is the shielding of the cable going to the encoder on the back of motor for that axis. The wiring diagram shows the back of that (x=no lead in that location) plug with numbers corresponding to the colors on the leads in the pic of the encoder in post (11 Oct 2020 15:00 #185720). The other end of diagram shows the placement of leads at the 7i77 card TB3 location,(x=no lead in that location).

Many thanks to all the kind and talented people that make this place work so well.
I warmly welcome thoughtful help, or please point me in the direction to search.
Many, many thanks!