CK powered up but throwing error

[ShAne]

I have the older ck I have two. The original ck runs perfect the back up machine throws a error. I can try and home machine and it goes to corner and seems to go past boundary and make awful noise. Running fusion 360 and UGS. Seems the limit switches are activated before getting them causing machine to stop. I unplugged limit switches and same issue throws error. Error ...( Hard limit has been triggered. )

[bLouChip]

Inspect your Homing Limit switches closely and look for broken leads on the attached 1uf capacitor. Repair electrically with solder and then glue the capacitor body to the switch body. 

I had the same sudden symptom when homing after months of successful operation, the culprit was the capacitor on the X axis in my case but any could fail.  After I repaired it with just solder, it failed again a couple months later, at which time I assumed some high frequency vibrations were fatiguing the capacitor leads causing the breakage since the capacitor just hangs in the air. I repaired again with solder and that time I glued the capacitor to the switch body.  No issues for nearly 2 years.

As for Hard Limit Alarm, I believe the MR recommendation is to run with Hard Limits disabled $21=0.  When hard limits are enabled, the controller is sensing for limit switch closure all the time, so any electrical noise on the wires will throw a false alarm, and it is very very likely to occur.   When hard limits are disabled, then only during homing cycle does the controller sense for limit switch closure, and normally you don't have noisy cutters like routers, spindles, and plasma operating at that time either.  Also, unless you have installed another set of limit switches at the opposite end of each axis, then running with hard limits enabled only protects one end of each axis. Rather run with Soft Limits enabled $20=1.

[Derek the Admin]

Sometimes the switch is set up in a way that makes it "almost engaged" before actually snapping over to be engaged. This isn't the case, is it?