Ok, thanks. Obviously my issue is with the machine itself as the probe works correctly when the spindle is unplugged. I will look further into the wiring to find my issue and deal with it on other forums for the machine, especially the spindle wiring as all the info I can find online is as clear as mud. Thanks for your patience and all your help. May your new year be the best ever.
Spindle is FINE (repeated several times above in thread) Stop focusing on the Symptom As above More importantly This shows the DC side of the short is somewhere in limits (or motors, but more likely limits. Easy to eliminate by repeating test one plug at a time in the same methodology as the test you did there. My money is on a Z switch shorting to frame I mentioned the possibility earlier And latest tests sort of confirm I am not alone in that line of thinking either Alex thinks the same