I recently upgraded the steppers on my G0704 from steppers to DMM 400W servos on the X & Y, and 750W on the Z, all with DYN4 drives. Everything progressed well until a shakedown run when the 400W X and Y axes started throwing random servo alarms for Lost Phase or Overheat. Sometimes the alarms occur less than a minute into a program, so the motor is still cold, so the Over Heat is false. The servos were auto-tuned using the DMM software. Gear and Line settings are 500 & 500. I'm using Mach3 with a 25kHz pulse, though I've also tried a 45kHz pulse which had the same results. DMM support has been great with many emails exchanged, but thus far we're unable to track down the cause. The 400W servos behave very well, until at some random point in the program either the X or the Y servo will alarm out. The drives are connected to a C11GD breakout board and are set to run in Pulse/Dir mode per the DMM guide. The 750W Z axis has performed very well from day 1, and has never alarmed out, so I don't think its a random noise issue, or a pulsing issue from Mach3 since the Z is perfectly healthy. Has anyone experienced DMM servos/drives plagued with "false" alarms? Any feedback is appreciated.

Has anyone had success with the 400W DMM servos on a G0704 type machine? They seem to have plenty of power to slew the axes at over 200 IPM but this alarm issue is making wonder if they are undersized. On paper, they produce more than twice the power of the Nema 23 steppers they replaced.

DMM has recommended that I move from a brand new $100 C11GD breakout board to a Smoothstepper. They believe its a pulse related issue, exacerbated by the C11GD breakout board. I don't agree since the Z-axis has been perfect from day 1. The 400W servos are driven by DYN4-L01 drives, wired at 120V AC with all the proper Shaffner EMI filters in place, per the DMM guide. I have 6A filters on the drive's power side, 1A on the logic side, and a large 30A filter on the main AC input, per the guide. I was surprised that these took 120V AC rather than 240V but these motors are only 60V so DMM only recommends 120V AC for these. The z-axis is wired at 240V per the DMM guide.

Things I've already tried"
1. Re-tuned the troublesome X and Y axes a dozen times, no change.
2. Stepped down from a 45kHz pulse to a 25kHz pulse, no change.
3. De-tuned the Mach 3 axis velocity and accelerations way down to benign values, no change.
4. Run a dozen different programs to make sure its not bad G-code. Issue occurs in all programs, even during slow 15IPM light duty cuts.

-Mike