amplifier fault troubleshooting

if you measure across A+ , A- you should get alternating polarities like your +3.5V, -3.5V

If you measure A+, A- relative to ground they should be close to ground in one state
and > 2.4V in the other.

Ah, thanks for setting me straight.
Since I'm getting encoder signals to the 7i97t, but it's not getting that signal to linuxcnc, than I assume that the high frequency start somehow damaged it.

The 7I97T is likely repairable if only the encoder interface chip(s) are damaged.

You might check if any encoder inputs work.

PCW wrote:

This:

net plasmac:breakaway joint.0.amp-fault-in <= hm2_7i97.0.inmux.00.input-04-not

Looks like the only thing that can generate a amplifier fault

Why would you connect the torch breakaway switch to an amplifier fault? That is wrong