How to downgrade?

You can usually use Synaptic to downgrade versions (within a release) easily enough.
Select the package you want to change, from the Package menu click Force Version (or Ctrl+E), select the version you want to run, then click Apply.

Thanks Todd,

but I have already started to reinstall so I can get back to basics and see what is wrong with the box I have.

Cheers
Bengt

Hmmm.

Obviously there is something wrong so I have to ditch that one.

I have another PC under latency test right now, www.jetwaycomputer.com/NC91.html
Servo thread Max jitter 8178916
Base thread Max jitter 302270
Is this a candidate (read usable) for 7i76E running AC Servos with Step/dir?

Debian Stretch, RT-PREEMPT, LinuxCNC 2.7.x still r1 no update no upgrade

Cheers
Bengt

Have you tried running a mem test or checking the HD. Perhaps it is a simple fix. Did you check the capacitors on the main board for obviously failing ones?

No, it is just too much work and it's an old box. It is over 12 years so I do not think it will cut for RT-PREEMT.


So I hope I can use the Jetway NC91 for my Mesa 7i76E boards.

tecno wrote: Servo thread Max jitter 8178916
Base thread Max jitter 302270
Is this a candidate (read usable) for 7i76E running AC Servos with Step/dir?

No, that's terrible.

8mS jitter on a 1mS thread will never work.

Are you sure it is booted into the preempt-rt kernel? (uname -a will tell you)