Is it my 251X? How to troubleshoot lost steps.

[rlrhett]

I have a home built system using the C-10 BOB and G251X controllers. System has been rock solid, until yesterday. I suddenly noticed that I was loosing steps in the z-axis. I would zero the z and start cutting. After a minute or so I noticed that the z was too high (I suppose that is better than too low :-) ) I zeroed again. Again after a minute of cutting it was off. I did it a third time, same problem. After a few z-level passes it thought it was about 1/8" lower (according to the DRO's) than it really was.

Manually jogging the machine seems to work fine. I checked all the wires and see nothing loose, pinched, burned, etc. The axis seems to be moving smoothly (typical ACME precision screw with dumpster cnc anti back lash nut setup). It is not bound up in any way I can tell.

I did notice the z-axis G251X hot to the touch, the other two axis were merely warm.

How do I troubleshoot? I don't just want to get a new G251X only to discover it is something else, but I don't know how to test. Suggestions?

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[ger21]

Put a fan on it and see if it fixes the issue.

[rlrhett]

Good God, Man! Are you on every single thread? You're freakin' amazing!

[rlrhett]

Keeping a fan on it seems to make no difference. Worse, the problem is intermittent. It completely disappeared as a problem for one job, only to re-appear on the next. Next step is to check the wires for a short. I am also concerned that there is a problem with the terminal block on the G251X. I disconnected all the wires and re-connected them to make sure that none of the wires had slipped loose. The terminal block seems to "wiggle" a little on the circuit board. Not much, but I'm out of ideas as to what may be happening.