Hi.
yikes! That sounds like an expensive learning curve, so you have two Pokeys and one ESS boards which are potentially faulty.
I would certainly like to get to the bottom of that before I did anything else.
You may have noted that in the other thread:
http://www.machsupport.com/forum/index.php/topic,37598.msg257219.html#msg257219that there is a possibility that current is leaking into the frame of your machine. My steppers do so, an unusual mechanisim but it happens.
The first time I knew anything about it I had removed my spindle and inadvertently removed the earth bonding. I only recognized it when I got a good
'tingle' off the machine while trying to track a fault with my Estop. It turns out that the leakage blew the input buffer on my BoB, fortunately it didn't affect
my ESS. It has made me a little more cautious though!
To be honest I would go back to square one, disconnect EVERYTHING off your machine. Particularly the spindle and driver. I would remove the earth bonding also. THEN I would hook up things ONE AT A TIME
measuring the voltage of ALL metal parts of the frame against a KNOWN GOOD POWER EARTH. This is exactly what I did with my mill until I had it nailed down as to what components (steppers)
were contributing leakage current (approx. 1mA each) and under what circumstances.
Craig