upgraded from 2.5 to 2.6 tuning issues

Not sure but does oscillation frequency change if you lower P?

Right now it looks like 120 Hz power supply ripple

I'm pretty sure the frequency stays the same. I will verify that tomorrow.

If it is a power supply issue I'm assuming it is the encoder and control psu I should be looking at and not the servo psu. The encoders are ttl so they are probably more susceptible to noise.

I would think that if the problem were with the encoder you would be seeing drift issues.

What I think Peter is hinting at is something somehow causing a ripple in your analog control signal.

What happens if you back off the P, can you get it to smooth out? You might have to back it off a lot.

As expected this was not a 2.6 issue.

I switched the 12V and 5V channels from the machine power supply to the computer PSU and the issue has went away.

Hmm. I wonder if this had anything to due with the mother board failure??

Thanks
For all your help