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

It is my belief that this is the type of encoder that is required; single ended encoder. With a 2000 count?

I put question to the tech at AMC, the response: single ended encoder input only!



Need to confirm the correct encoder.
Many thanks!

Edit: I swapped the motor and encoder from the "x" axis to the "y" axis and the "x" axis motor would not work with the setting that the "y" axis had moved under power. It is my belief that the encoder on the "x" axis has the issue. I was unable to tune the motor.

Before buying a new encoder, I would load each encoder channel into halscope and compare it to the one that works to see if it indeed is faulty. Assuming they are still wired to the 7i77.
If your machine has handwheels you can move the table without powering up the motors and look for a clean square wave coming from the encoder.

If you are asking how to connect the encoder to your new drives, you should be able to just connect A and B and Ground if they get power from an external 5v (7i77). Someone correct me if I'm giving the wrong info please.

On my AMCs I use the old tach feedback but will be doing a BL setup soon for a 4th axis and will read in one encoder. So I'll be going through the same thing. Is it acceptable to say split a A, /A, B, /B, with a Y harness and tie one end to 7i77 using all channels and connect only A, B and Ground on the drive?

there is a part "goofed up" because tuning was impossible and if you hold the hand wheel for the "x axis" while the motor is energized it has vibration you can feel in your hand and never becomes firm against rotation.

I'll dig up my post from a while back tuning the amc. I recall having an issue with one pot setting (a recommended full cw or ccw? setting from the manufacturer) that just made it impossible for me to tune.
Check your reference pot gain. Try mid range. That should stiffen it up.

forum.linuxcnc.org/27-driver-boards/3860...rive-tuning?start=20

OT-CNC, Many thanks! This is comment from the AMC tech about encoders: The AB15A100 only accepts a single ended encoder input. If you do have a differential encoder, you can just use the A+ and B+ lines and don't connect the /A and /B signals. It will still work as a single ended signal, you just won't have the benefits of a differential signal.

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. The hand wheel needs to be much stiffer. I will try looking for "a clean square wave coming from the encoder" & try the y axis as well. I will read your link, and evaluate POT 1 adjustment.

The encoders I see available have a coupling to motor shaft, I can see how covenant a factory original is. Ideally I would like a after market brand. I still wonder about encoder count, I realize it is referenced in other areas of the program and not locked in stone.

Many thanks

For replacement encoders, I have used US Digital E5s. They have many options and are affordable. You may find a direct replacement with correct mounting tabs to fit your motor if you search a bit. I would get their cable with connector as well.
2000 count should be fine. What are you doing with the original Track Encoder, the table mounted unit? What count was that?

Many thanks, OT-CNC!! I have reached out to the people at US Digital, gave a pic of the end of encoder and motor data sheet, but still need some of the information below. I have 2 low power power supplies in cabinet, 1 of them I can read, says 24 VDC and leads go to 7i77 card at the Orange location in pic. The other small power supply I cannot read but I believe the leads go to the very right hand end of the pic and makes connection (I do not think this pic shows the location).

The pin out
The power supply voltage to the encoder
The signal output type from the encoder
The signal out voltage level from the encoder

From OT-CNC: "What are you doing with the original Track Encoder, the table mounted unit? What count was that?" All that is gone, if I thought it was of interested I would of saved it?

many thanks

If it's a TTL level encoder it's 5v. That's what the 7i77 reads. The large orange connector on that board is the field voltage connection and is your 24v, used for limits, home switches etc. The encoders operate on 5v. You power the encoders from the 5v on the 7i77 encoder connector.
Make sure you follow the mesa manual on jumper selections as you don't want to power the 5v twice. It either gets power from the main card, 5i25 etc or external. Not both. I assume you already know that since you can read in the encoder...